To:

Subject:








Leaders:

Cooperators:


American Can Company ,i

Relationship of Heat Treatment to the Quality of Processed Citrus

Juices and Concentrates covering the work done under the grant-in-

aid supplied by the American Can Company plus various phases of

work done by cooperators from the Staff of the Florida Experiment

Station and Florida Citrus Commission from June 1952 to June 1953.

A. H. Rouse (grant-in-aid fellow) and C. D. Atkins.

R. Patrick, R. L. Huggart, E. C. Hill, J. H. Dietz, E. L. Moore and

R. W. Olsen.


TABLE OF CONTENTS

1. Introduction

2. Time-temperature relationships for heat inactivation of pectinesterase
in citrus juices.

3. Time-temperature-fold relationships for heat inactivation of pectinester-
ase in citrus juices.

4. Distribution of total pectin and pectinesterase in citrus fruits.
5. Effect of concentration on clarification, pectinesterase activity, and
pectin in citrus concentrates at varying folds.
6. Effect of storage temperatures on pectinesterase retention in citrus juices.

7. Clarification in heat-treated Pineapple orange concentrate.
8. Study of flavor in heated and unheated citrus juices and concentrates.
9. Maturity study of Pineapple orange.
10. Correlation of pectic substances and related factors with "cloud" sta-
bility and gelation in citrus juices and concentrates.
11. The effect of heat treatment on the survival of microorganisms in single-
strength and concentrated orange juice.

12. Outline for the coming season (1953-54).

13. Literature cited.

Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429h 6/6/53 AHR




-2L.


1, Introduction

Since the general purpose of this project is to investigate the application

of heat to citrus juices and concentrates as a possible means of eliminating en-

zymic (gelation, clarification, and off-flavor) and microbiological (off-flavor)

changes during processing and also during storage, the progress reported herein

is not only a continuation of June 30, 1952 Progress Report but opens the way to

what some of these changes are and where they take place.

The first part of this project concerning the heat treatment of single-strength

juices at several pH levels by means of a tubular pasteurizer in a series of temp-

eratures and holding times and time-temperature relationships is completed. The

heat inactivation of pectinesterase in folded juices or heating between the stages

has not been completed although part of it is presented in this report.

Eight manuscripts have been published this past year from July 1952 to July

1953, as the results of this project.

Those articles that have been published in either Food Technology or Food

Research are:
1) Heat inactivation of pectinesterase in citrus juices.
2) Further studies on heat inactivation of pectinesterase in citrus juices.
3) Gelation and clarification in concentrated citrus juices. III. Effect
of heat treatment of Valencia orange and Duncan grapefruit juices prior
to concentration,
4). A rapid method for estimating pectic substances in citrus juices.
The following articles have been published in the Proceedings of the Florida

State Horticultural Society.
5) Effect of concentration on clarification in concentrated citrus juices.
6) Clarification in heat-treated Pineapple orange concentrates.
7) Changes in pectic substances in Valencia orange juice during concentra-
tion.
8) Pectinesterase retention in citrus juices stored at various temperatures.


Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and-Florida Citrus Commission,
Lake Alfred, Florida
429 6/4/53 AHR


0 -'70








2. Time-Temperature Relationships for Heat Inactivation of Pectinesterase
in Citrus Juices,


This investigation was concerned with the determination of time-temperature

relationships for inactivation of peotinesterase in citrus juices at several pH

levels when retained in the pasteurizer for 0.8, 3, 6, and 12 seconds. Parson

Brown, Pineapple, and Valencia orange juices were prepared to contain 8% pulp by

volume and pH levels of 3.5 and 4.1, whereas Duncan grapefruit juice contained 8%

pulp by volume and pH 3.3 and 3.8. Dancy tangerine juice contained 10% pulp by

volume and pH 3.8.

The juices used in this investigation were prepared by extracting the juice,

pulp, and seeds with moderate pressure using a Rotary juice press. The seeds were

separated by a rotating reel and the juice finished in a Food Machinery, Model 35,

Finisher with a 0.030 inch perforated screen to yield a juice of 8% and 10% pulp

by volume as preferred. The finished juices were deaerated and cooled in an am-

monia-jacketed deaerator with the juices exposed to a vacuum of 27 inches for one

hour during the cooling process. The juices were then poured into 10 gallon drums

and stored at -8F. until needed. Prior to heat treatment tests the juices were

thawed and passed through a Weil turbine pump to obtain a homogenous mixture of

juice and pulp satisfactory for the tests, Because of the grinding action of the

pump the juices reached a temperature of 100F., however, they were immediately

cooled to room temperature.
The pasteurizer used in these tests contained three heating coils of 1/8 inch

I.D., and one coil of 1/16 inch I.D. stainless steel tubing. Hot water was circu-

lated around the heating coils. The flow rate was adjusted in each tube to 560 ml.

Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429a 6/4/53 AHR





-4-


per minute, The juices were in contact with heat in the 1/8 inch tubes for 12, 6,

and 3 seconds and in the 1/16 inch tube for 0.8 second; these times being required

to raise the juices from room temperature to the desired temperature. All temper-

atures were controlled by a Brown potentiometer pyrometer and checked constantly

with a Bureau of Standards thermometer.

Time-temperature relationships for heat inactivation of pectinesterase in

Parson Brown, Valencia, and Pineapple orange juices; Duncan grapefruit juice; Dan-

cy tangerine juice are presented in Tables 1, 2, 3, 4, and 5, respectively. Com-

plete inactivation of the enzyme in Parson Brown juice, pH 3.5, was obtained at

1950F., 2000F., 2050F., and 2050F, when retention times in the pasteurizer were 12,

6, 3, and 0.8 seconds, respectively, whereas the inactivation temperatures for this

juice, pH 4.1, were 2000F., 205F., 2100F., and 2100F. for the above mentioned re-

tention times. Valencia and Pineapple orange juices, pH 3.5, when heated for 12, 6,

3, and 0.8 seconds were completely inactivated of pectinesterase at 1900F., 1950F.,

2000F., and 2050F., respectively, while these juices, pH 4.1, were inactivated at

either 2050F. or 2100F. with these holding times. Duncan grapefruit juices at pH

3.3 and 3.8 when heated for 12 seconds required 1900F. and 1950F., for 6 seconds

1950F. and 2000F., for 3 and 0.8 seconds 2000F. and 2050F. for complete inactiva-

tion of the enzyme. Dancy tangerine juices, pH 3.8, when heated for 12, 6, 3, and

0.8 seconds at 1950F., 2000F., 2050F., and 2100F., respectively, were completely

inactivated.

Any partial inactivation of the enzyme in these five varieties of citrus

juices at several pH levels can be obtained from the tables.


Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429b 6/5/53 AHR









TABLE I


Time-temperature relationships for heat inactivation of pectinesterase in Parson
Brown orange juice, pH 3.5 and 4.1


Holding Time 12 seconds 6 seconds 3 seconds 0.8 second
Inactivation Inactivation Inactivation Inactivation
Temperature pH 3.5 pH 4.1 pH 3.5 pH 4.1 pH 3.5 pH 4.1 pH 3.5 pH 4.1
F. % % % % % %- %
125 51.5 12.8 8.3 5.4 2.9 1.9 0.0 0.0 0.0
135 57.0 44.7 13.6 27.0 11.4 13.1 8.8 4.9 3.2
145 63.0 83.8 34,8 70.2 23.6 46.3 16.0 33.8 11.o
155 68.5 89.4 70.2 83.8 54.5 80.1 31.7 76.0 24,.3
165 74.0 91.6 89.0 89.6 81.6 89.0 68.1 87.6 63.2
175 79.5 93.1 92.7 91.0 908 90.7 89.0 90..5 86.5
185 85.0 96.6 93.9 93.1 92, 92.9 92.1 91.3 90.8
190 88.0 98.6 95,7 94.5 94.0 94.3 94.0 92.8 92.7
195 90.5 100.0 97.0 97.9 97;0 97.9 95.2 95.0 93;9
200 93.5 1 -00'0 100o0 98,1 98.6 97.0 98.6 95.7
205 96.0 -- -- 100.0 100.0 98.8 100.0 97.0
210 99.0 100.0 100.0

Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429c 6/5/53 AHR










TABIE 2


Time-temperature relationships for heat inactivation of.pectinesterase in Valencia
orange juice, pH 3.5 and 4.1


Holding Time 12 seconds 6 seconds 3 seconds 0.8 second
Inactivation Inactivation Inactivation Inactivation
Temperature pH 3.5 pH 4.1 pH 3.5 pH 4.1 pH 3.5 pH 4.1 pH 3.5 pH 4.1
F. OC. % % % % % %. ..%. *%
125 51.5 7.5 3.9 4.3 1.0 1.1 0.0 0.0 0.0
135 57.0 33.0 8.7 20.2 2.9 4.3 0.0 3.3 0.0
145 63.0 77.7 14.4 58.5 8.7 34.0 4.3 23.9 0.9
155 68.5 81.9 43.3 77.7 19.2 74.5 7.8 71.7 5,6
165 74.0 90.4 77.9 90.2 59.6 90.2 37.9 89.1 31.8
175 79.5 94.7 90.4 93.6 84.6 92.6 72.4 90.2 71.0
185 85.0 97.9 93.3 94.7 91.4 93.6 87.9 93.5 87.9
190 88.0 100,0 95.2 96.8 93.3 95.7 91.4 94.6 90.7
195 90.5 96.2 100.0 95.2 98.9 92.2 95.7 91.6
200 93.5 -. 99.0 8 98.1 100.0 95.7 98.9 95.3
205 96.0 100.0 99.0 98.3 100.0 98.1
210 99.0 -- -- 100.0 100.0 100.0

Citrus Station dimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429d 6/5/53 AHR









TABLE 3


Time-temperature relationships for heat inactivation of pectinesterase in Pineapple
orange juice, pH 3.5 and 4.1


Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429e 6/5/53 AHR


Holding Time 12,seconds 6 seconds 3 seconds 0.8 second
Inactivation Inactivation Inactivation Inactivation
Temperature pH 3.5 pH 4.1 pH 3.5 pH 4.1 pH 3.5 pH 4.1 pH 3.5 pH 4.1
OF., c.. % % % % % % %I %,
125 51.5 16.7 5.3 8.8 0.0 3.9 0.0 1.0 0.0
135 57.0 49.0 11.5 28.4 7.1 16.7 0.0 13.7 0.0
145 63.0 88.2 31.9 77.5 23.9 57.8 15.0 45.1 9.7
155 68.5 90.2 71.7 89.2 53.1 88.2 35.4 85.8 31.9
165 74.0 93.1 87.6 92.2 80.5 90.2 69.0 89.2 62.0
175 79.0 94.1 90.3 93 .1 89.4 92.2 86.7 92.2 85.0
185 85.0 98.0 92.9 94.1 91.2 94.1 90.8 93.6 87.6
190 88.0 100.0 94.7 98.0 92.9 96.1 91.5 94.5 90.8
195 90.5 96.5 100.0 94.7 98.0 94.3 96.1 91.5
200 93.5 98.2 98.2 100.0 95.0 98.0 94.7
205 96.0 100.0 -- 100.0 98.2 100.0 98.2
210 99.0 -- -- 1- 100.0 100.0









TABLE 4
Time-temperature relationships for heat inactivation of pectinesterase in Duncan grape-
fruit juice, pH 3.3 and 3.8

Holding Time 12 seconds 6 seconds 3 seconds 0.8 second
Inactivation Inactivation Inactivation Inactivation
Temperature pH 3.3 pH 3.8 pH 3.3 pH 3.8 pH 3.3 pH 3.8 pH 3.3 pH 3.8
'F, 0C.. % % % % %. %
125 51.5 48.7 22.0 40.7 17.2 36.7 0.0 28.0 0.0
135 57.0 78.8 28.3 64.3 22.8 55.2 1.6 45.0 0.0
145 63.0 82.7 72.1 82.0 32.3 80.4 18.8 77.2 13.1
155 68.5 88.1 82.6 86.8 76.4 85.3 55.8 84.5 45.2
1 165 74.0 89.9 86.7 88.8 84.4 86.9 81.7 86.1 75.9
175 79.5 93.9 90.7 92.4 90.7 90.1 86.0 88.5 84.1
185 85.0 96.2 94.6 93.9 92.3 92.4 88.5 90.9 86.6
190 88.0 100.0 97.7 97.7 96.1 94.7 92.4 94,0 89.8
195 90.5 -- 100.0 100.0 98.4 98.5 96.2 97.8 92.2
200 93.5 -- -- 100.0 100.0 98.4 100.0 96.1
205 96.0 -- -- -- 100.0 -- 100.0


Citrus Station Jlimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429f 6/5/53 AHR










TABLE 5

Time-temperature relationships for heat inactivation of pectinesterase in
Dancy tangerine juice, pH 3.8


Holding time 12 seconds 6 seconds 3 seconds 0.8 second
Inactivation Inactivation Inactivation Inactivation
Temperature pH 3.8 pH 3.8 pH 3.8 pH 3.8
OF. oc. % % %
125 51.5 18.1 16.4 13.0 6.1
135 57.0 31.7 24.0 20.5 7.2
145 63.0 57.7 44.4 35.2 24.6
155 68.5 74.1 64.2 57.7 51.2
165 74.0 80.6 75.8 74.1 70.7
175 79.5 84.0 80.6 78.5 74.1
185 85.0 87.4 84.0 81.6 77.5
190 88.0 93.5 90.4 86.7 80.6
195 90.5 100.0 93.5 92.2 84.0
200 93.5 100.0 93.9 90.4
205 96.0 -- 100.0 93.5
210 99.0 -- -- -- 100.0

Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Cnomission,
Lake iAfred, Florida
429g 6/5/53 AHR




-10-


3. Time-Temperature-Fold Relationships for Heat Inactivation of Pectines-
terase in Citrus Juices.

Orange juices at 1, 2, 3, and 4-folds were heated to temperatures ranging

from 1250F. to 210OF. in 3, 6, and 12 seconds to determine the relationship of

time, concentration, and temperature upon pectinesterase activity. Previously

all the data accumulated were based on single-strength juices. The effect of

heat as a "cloud" stabilizer in these folded juices, measured in terms of light

transmission, was also desirable.

Experiments on this phase of heat treatment were begun the latter part of

February at which time Pineapple orange juice had a pH 3.8. As a result only one

pH level was used for this variety of orange. The varying folds of Valencia orange

juices were made at two pH levels, pH 3.6 and pH 4.1, but results at this time are

completed only on the pH 3.6 level.

Pineapple and Valencia oranges were extracted on the Rotary press with moderate

pressure and the expressed juices finished in a Food Machinery, Model,35, finisher

with a 0.030 inch perforated screen. The Pineapple juice contained a pulp content

of 9,0% and pH 3.8, whereas the two finished Valencia juices contained 7.5% pulp

by volume and pH 3.6 and 4.1. The Pineapple orange juice was concentrated to 2,

3, and 4-folds, whereas the Valencia orange juice was concentrated to 42oBrix and

then cut-back to 1, 2, and 3-folds with cooled distilled water. The folded juices

were then poured into 10 gallon containers and stored at -8F. until needed.

The time-temperature-fold relationships for the heat inactivation of pectin-

esterase in Pineapple and Valencia orange juices are presented in Tables 6 and 7,

whereas "cloud" stability of the juices heated in six seconds at the various folds

is shown as degree of clarification in Tables 8 and 9.

Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429i 6/8/53 AHR










TABLE 6


Time-temperature-fold relationships showing the percentage heat inactivation of pectinesterase
in Pineapple orange juice at varying concentrations, pH 3.8

" , ", i ,,
Concentration 1-fold 2-fold 3-fold 4-fold
SHolding time-seconds 12 6 3 12 6 3 12 61 3 12 6 3

STemperature
. j C.. % % % % % % % %. % %
25 51.5 53.1 47.5 445 18.4 14.7 10,8 12,7 11,0 9,8 6.5 1,3 0.3
135 57.0 61.8 54.4 48.1 32.1 29.3 255 36.0 35.1. ,2 18.7 9.6 3.7
145 63.0 83.3 67.7 63.2 76.0 53.4 42.5 70.1 4I 35.3 44.1 36.5 28.3
155 68.5 91.1 89.5 79.3 88.4 82.4 77.9 90.4 88.1 74.7 88.5 74.7 67.2
165 74.0 194.2 93.0 92.4 90.5 88.4 87.4 91.8 91.2 88.8 90.3 88.7 86.6
175 79.5 95.4 94.2 93.1 91.8 91.7 89.5 92.7 91.7 91.2 92.0 90.3 89.1
185 85.0 97.2 95.5 94.2 93.7 92.7 91.8 95.6 93.5 92.7 94.9 93.9 93.1
190 88.0 i 98.8 97.2 i 96.0 97.1 94.7 93.7 99.3 94.3.3 9.3 97.4 96.5 95.6
195 90.5 1100.0 98.3 97.2 100.0 97.1 94.8 100.0 97.9 97.1 100.0 98.4 96.5
200 93.5 10.0 i 98.8 100.0 97.8 100.0 9.3 98.3
205 96.0 1 -- 00.0 -' t1. -- -100.0 100.0
.... -- lo, -- l, O -- ,o~ 8;


Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429j 6/8/53 AHR









TABLE 7


Time-temperature-fold relationships showing the percentage heat inactivation of pectinesterase
in Valencia orange juice at varying concentrations, pH 3.6


Concentration 1-fold 2-fold 3-fold 4-fold
Holding time-seconds 12 6 3 _12 6 3 12 6 3 12 6 3
Temperature '
.F% .% % % % % % % % % %
j125 51.5 22.4; 17.5 11.9 23.0 18.1 14.9 19.0 16.5 10.6 15.6 13.0 9.2
135 57.0 51.41 27.4 16.9 40.3 34.0 26.2 44.8 27.6 21.6 24.5 23.7 16.4
145 63.0 84.7 70.2 54.4 77.0 73.2 58.7 82.4 68.1 54.2 73.9 58.9 52.2
155 68.5 89.1 87.4 84.9 84.2 82.9 81.8 88.7 86.9 84.9 86.5 85.1 83.0
165 74.0 90.0 89.2 87.5 88.9 87.4 85.9 90.9 88.8 87.9 91.9 88.7 87.7
175 79.5 91.7 90.2 89.2 93.0 90.0 88.9 93.8 91.1 90.1 94.4 93.4 92.3
185 85.0 94.3 91.8 90.2 96.0 93.0 91.4 97.2 94.0 92.2 96.5 95.5 94.4
190 88.0 97.6 94.2 93.5 98.5 96.1 94.5 99.0 97.2 95.1 97.8 96.5 95.5
195 90.5 il00O0 97.6 96.0 o00.0 98.5 97.1 100.0 98.9 97.2 100.0 98.9 98.0
... 93.5 0 1,99.0 looo 0 98.9
200 93.5 -- 100.0O 98.4 -- 100.0 98.5 -- 100.0 99.0 98.9
205 96.0 -- 100.0 -- 100.0 - 00.0 100.0

Citrus Station Mlmeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429k 6/8/53 AHR









TABLE 8


Temperature differentials in a tubular pasteurizer between the juice or
concentrate temperatures and the heating medium temperatures


i Temperature differential
Concentration 1-fold 2-foldi 3-fold 4-fold
Processing
time-seconds 12 6 3 10.8 12 I 6 3 12 6 3 12 6 3
Processing temps. I -
oF. oF. o, OF. OJF.. oF. oF. F. IF, OF. oF. OF OF.
125 0.0 0,0 j 7.0 6.5 0.0 1.0 14.5 0.0 3.5 22.0 0.0 6.0 29.0
135 0.0 1 1.0 9.0 8.5 0.0 1.5 17.0 0.0 4.5 25.0 0.0 7.0 34.0
U45 0.0 i 1.0 10.5 9.0 0.0 2.0 20.0 0.0 5.0 28.0 0.5 9.0 37.0
155 1.0 1.0 10.5 0.0 0.0 2.0 19.5 0.0 5.5 27.0 0.5 10.0 39.0
165 1.0 2.0 11.5 12.0 0.5 3.5 19.5 0.5 6.0 29.0 1.0 10.0 36.5
175 1.0 2.0 11.5 14.0 1.5 4.0 19.5 1.0 6.0 27.0 1.0 9.5 39.0
185 1.5 3.5 11.0 14.0 1.5 4.0 17.0 1.5 5.0 25.0 1.5 8.5 36.0
190 1.5 4.0 12.0 13.5 2.0 4.5 17.0 1.5 5.0 28,0 1.5 8.0 37.5
195 1.5 3.5 11.0 13.0 2.0 40 19.0 1.5 5.0 26.5 2.0 7.0 38.0
200 4.0 13.0 12.0 3.5 18.0 5.0 26.5 6.5 39.5
205 -- 3.5 13.5 12.0 -- 16.5 -- -- 28.0 -
210 13.0 12.0 -- i 17.5 -- -- -- -- -

Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
4291 6/8/53 AfR






-14-


Both the Pineapple orange juice, pH 3.8 and the Valencia orange juice, pH 3.6,

at 1, 2, 3, and 4-folds, when heated for 12, 6, and 3 seconds, required 1950F.,

2000F., and 205F., respectively, for complete inactivation of pectinesterase

activity. Concentrating the juices and then heat treating them did not result

in lower temperature for complete pectinesterase inactivation. However, the gen-

eral trend was to inactivate a higher percentage of the enzyme at the lower fold

when heated from 1250F, to 1550F., and above this temperature the percentage of

inactivation for a specific holding time regardless of fold was about the same.

Temperature differentials in a tubular pasteurizer between the actual heated

juice and concentrate temperatures and the heating medium temperatures for 1, 2,

3, and 4-folds for 0.8, 3, 6, and 12 seconds are presented in Table 8. There is

no significant temperature differential between the temperatures of the 1 and 4-

fold juices and the temperature of the heating medium for the 12 seconds holding

time, but the temperature differential for the 3 second holding time varied from

7 to 13.50F. for the 1-fold juices and 290 to 39.50F. for the 4-fold juices.

Cloud stability for Pineapple and Valencia orange juices at 1, 2, 3, and 4-

folds when heat treated for six seconds from 1250F. to 2000F. are presented in

Tables 9 and 10 as clarification measured by percentage of light transmission of

centrifuged reconstituted juice. Clarification of these juices is shown initially

and after short-term storage for 24 hours at 800F. Initial clarification on the

Pineapple juices is given only for the 1-fold, whereas initial clarification on

the Valencia folded juices is given for each fold. As previously pointed out the

Valencia juice was concentrated to 42oBrix and cut to 120, 230, and 330Brix con-

centrates with distilled water. The results in Table 10 would indicate that

Valencia juice, pH 3.6, concentrated to 4-fold and heated to 145F. had good cloud
stability after storage for 24..hours at 800F. However, all the previous work has
Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission
Lake Alfred, Florida
429e 6/9/53 AHR






-15-


shown that as the pH of the raw juice is raised to pH 4.1 a higher temperature is

necessary for pectinesterase inactivation. This part of the experimental work

is not completed.







































Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429p 6/9/53 AHR










TABLE 9


Cloud stability of Pineapple orange juice at varying folds when heat treated in
six seconds and placed at short-term elevated storage temperature


Thermal i Degree of clarification1
treatment Initial _After 24 hours storage at 80F. (26.50,.)
F. oC. 1-fold 1-fold 2-fold 3-fold 4-fold
Control (not heated) 64 Slight 68 Slight 96 Extreme 95 Extreme 92 Extreme
125 515 48 None 49 None 94 Extreme 94 Extreme t 91 Extreme
135 57.0 48 None 47 None 93 Extreme 93 Extreme 90 Extreme
145 63.0 47 None 46 None 83 Definite 88 Extreme 84 Definite
155 68.5 49 None 50 None 64 Slight 63 Slight 71 Definite
165 74.0 48 None 46 None 59 None 61 Slight 72 Definite
175 79.5 49 None 47 None 58 None 65 Slight 76 Definite
185 85.0 j 47 None 48 None 55 None 63 Slight 76 Definite
190 88.0 _47 None 45 None 53 None 63 Slight 78 Definite
195 90.5 46 None f 44 None 52 None 61 Slight | 76 Definite
200 93.5 46 None 45 None 51 None 60 Slight 78 Definite
1 Clarification measured by percentage light transmission of centrifuged reconstituted juice using 10 mm.
rectangular cell in Lumetron colorimeter with filter No. 730. Degree of clarification: 0-59% = None;
60-69% = Slight; 70-84% = Definite; 85-100% = Extreme.
Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429m 6/9/53 AHR










TABLE 10


Cloud stability of Valencia orange juice at varying folds when heat treated in
six seconds and placed at short-term elevated storage temperature


Thermal Degree of clarification1
treatment Initial After 24 hours storage at 80F. (26.50C.)
O E, OC. 1fold 2-1-fold 3-fold fold 4-fold
1-f ad 3-fod -fld -ffod
Control i(not heated) 53 None 51 None 53 None 47 None 59 None 73 Definite 91 Extreme 80 Definite
S125 51.5 46 None 46 None 55 None 47 None 53 None 63 Slight 89 Extreme 77 Definite
135 57.0 46 None 45 None 50 None 46 None 51 None 57 None 86 Extreme 71 Definite
145 63.0 45 None 44 None 50 None 145 None 48 None 47 None 67 Slight 53 None
S155 68.5 45 None 45 None 49 None 44 None 47 None 46 None 56 None 46 None
165 74.0 44 None 43 None 48 None 44 None 46 None 45 None 55 None 47 None
175 79.5 43 None 43 None 49 None 43 None 45 None 44 None 55 None 47 None
185 85.0 43 None 42 None 49 None 44 None 44 None 42 None 52 None 45 None
190 88.0 42 None 42 None 47 None 43 None 43 None 42 None 48 None 46 None
195 90.5 42 None 41 None 49 None 143 None j 43 None 41 None 49 None 44 None
200 93.5 41 None 41 None 49 one None 42 None 41 None 449 None .i 49 o 45 None
1 Clarification measured by percentage light transmission of centrifuged reconstituted juice using 10 mm.
rectangular cell in Lumetron colorimeter with filter No. 730. Degree of clarification: 0-59% = None;
60-69% = Slight; 70-'g = Definite; 85-100% = Extreme.
Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429n 6/9/53 AHR









4. Distribution of Total Pectin and Pectinesterase in Citrus Fruits,

In a study to determine the quantity of total pectin and pectinesterase activ-

ity in the various component parts of citrus fruits, it was believed that tis in-

formation would be of some significance to the citrus processor in evaluating the

type of component part to avoid in preparing his extracted juice. The distribution

of pectinesterase activity in the component parts of seven typical Florida Citrus

fruits was presented in the June 1952 Progress Report. The distribution of total

pectin in the component parts of the seven varieties of citrus fruits are presented

in Table 11. The component parts consist of the flavedo, albedo, rag, juice sacs,

seeds, and centrifuged juice from Dancy tangerines; Hamlin, Pineapple, Temple, and

Valencia oranges; Marsh Seedless and Duncan grapefruit.

The component parts referred to are briefly described as follows:

1) Flavedo, known as the epicarp, is the outer colored portion of the peel.
2) Albedo is the white spongy portion known as the inner mesocarp. This
also includes the central core.
3) Rag consists of the segment membranes or wall tissue enclosing the
juice sacs.
4) Juice sacs are the vesicles which hold the juice.
5) Seeds
6) Juice is the liquid contained in the sacs. The juice was centrifuged
to free it of insoluble solids.

Mature sound fruits were selected which were carefully separated by hand into

the component parts and analyzed for total pectin. The percentage of moisture with

the distribution of total pectin expressed as calcium pectate in the component parts

of citrus fruits on both a wet and dry basis are presented in Table 11. The pec-

tic content on a dry basis was found to be highest in the rag for Dancy tangerine;

Pineapple, Temple, and Valencia oranges; and Duncan grapefruit. In the Hamlin

range pectin was highest in the albedo and in the Marsh Seedless grapefruit

Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429q 6/9/53 AHR











Distribution of total pectin in


TABLE 11

the component parts of citrus fruits


S Flavedo Albedo Rag Juice sacs Seeds Juice
Variety i e, I a 0 i ) D 1 e D 0 Q
tof, ?* t + a1 V) t. 4l 4 4 3 4,rl 41
i i i po3 C o ai o m doC
0 0 CC 01 a Oo a WP a W 0 Ca 3
3_ o _Xa d 54 C> 14 1w a 3 3 o $






orange 73.6 3.9 114.8 72.1 4.4 15.7 78.2 4.3 19.9 83.6 1.8 .1.1 54.1 3.5 7.5 87.2 0.-1 0.9
Temple
orange 77.5 12.4 10.8 73.9 4.4 16.7 81.3 3.1 16.5 83.0 1.5 9.0 46.7 3.4 6.486.8 0.05 O0i4
Valenc ia



orange 172.4 5.0 18.1 68.2 8.7 27.5 1 .41 7.7 35.4 84.0 2.5 15.3 54.8 3.8 8.4 88.9 0.09 0.8
ta..ngein e ..... I !.- .. 5 .4 5 ._. .







Marsh
grapefruit 7. 6.8 31.2 80.5 2.7 8 .5 1. 5.5 44.7 2. 5 4 9.7 0.08 0.8
.i43appe. 20.0 1 8 14.61.7 i '
orange 775 21 73.9 4. 16.7 .33.1 16.5 83 .7 3 64880 05O




Dunan I
grapefruit 77.3 4.5 20.0 786 !2.8 13.0 82.8 4.1 24.1 87.5 1.6 12.7 54.7 2.2 5.1:90.1 10.08 0.8
Citrus Station limeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission
Lake Alfred, Florida
429u 6/10/53 AHR









pectin was highest in the flavedo. The juice was lowest in pectin content and

the seeds were relatively low. The juice sacs contained a good supply of pectin

ranging from 9 to 15.5% on a dry weight basis. The rag and juice sacs are the

two component parts which make up the majority of pulp in citrus juices or con-

centrates and it should also be noted that these two components also contained

the highest pectinesterase activity.

Pectinesterase activity is presented in Table 12 for several component parts

of Persian limes and Villafranca lemons.
TABLE 12

Distribution of pectinesterase in component parts of citrus
Component Persian limes Villafranca lemons
parts (PE.u.)g. (PE.u.)g.
wet dry wet dry
tissue solids tissue solids
Peel (flavedo and albedo) 0.0178 0.0698 0.0106 0.0521

Rag (segment membranes) 0.0036 0.0171 0.0018 0.0109

Juice sacs 0.0061 0.0458 0.0032 0.0263

Seeds 0.0035 0.0011

Juice 0.0014 0.0182 0.0070 0.0139

This enzymic activity has been determine on the various component parts of

9 varieties of citrus fruits. Of the component parts, the juice sacs from the

acid fruits such as the Persian limes and Villafranca lemons are not highest in

pectinesterase activity as the juice sacs from oranges and grapefruit. The peel
which includes the flavedo and albedo was highest in activity in these two citrus

fruits.

Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429r 6/9/53 AHR





-21-


5. Effect of Concentration on Clarification, Pectinesterase Activity, and
Pectin in Citrus Concentrates at Varying Folds.

During the 1951-52 citrus season, packs of juices and concentrates of vari-

ous folds were prepared from Duncan grapefruit and Valencia oranges to study the

effect of concentration on the rate and degree of clarification which may occur in

a concentrate because of enzymic action, Data were also secured on the pectines-

terase activity and the amount of water-soluble, sodium hexametaphosphate-soluble,

and sodium hydroxide-soluble pectin present in these various folded concentrates.

The sodium hexametaphosphate-soluble fraction represents the polyvalent insoluble

pectinates and pectates while the sodium hydroxide-soluble represents the proto-

pectin fraction. The possibility of using a high concentration as a means of

stabilizing citrus concentrates to enzymic change was considered with the thought

in mind of producing unheated concentrates which would be suitable for use where

space is at a premium and storage at 0F. is not feasible. Possible markets are

the submarine service of the armed forces and the juice dispenser field where con-

centrate is held at temperatures above 200F. and the concentrate is reconstituted

as it is dispensed.

Clarification of the cloud in concentrates has been shown to be indicative of

product stability and quality. To eliminate the possibility of changes in the pro-

ducts that could be caused by differences in processing time, most of the juices

and concentrates were processed in the evaporator for an equal time interval of 2

3/4 hours, the time necessary to obtain a concentration of 65OBrix. This was

accomplished by feeding distilled water into the evaporator to maintain a constant

Brix from the time the desired Brix was reached until the processing time of 2 3/4

Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429s 6/9/53 AHR






-22-


hours was completed. However, the 750Brix grapefruit and the 740 and 78OBrix

orange concentrates were obtained in a manner duplicating the products below 650

Brix with the exception of the pan temperature and the time of evaporation. The

pan temperature rose rather abruptly to 85F. after a Brix of 650 was reached and

the processing time had been extended to 4 1/2 hours.

Effect of concentration on rate of clarification in Duncan grapefruit and

Valencia orange concentrates is presented in Tables 13 and 14, respectively.

Pectinesterase activities and the quantity of the three pectin fractions for

Duncan grapefruit and Valencia orange concentrates are shown in Tables 15 and 16,

respectively. Also presented in these tables are data giving the enzyme activi-

ties and the pectin analyses when the concentrates are calculated back to the orig-

inal degree Brix of the juices.

The greatest rate of clarification occurred in Duncan grapefruit concentrates

in the range of 180 to 41LBrix. Stability to clarification for three months stor-

age at 40F. was obtained only when concentration was above 610Brix.

In the Valencia orange concentrates clarification occurred at the greatest

rate in the range of concentrations of 180 to 51Brix. Only those products con-

centrated to 74Brix or above were stable during three months storage at 400F.

Pectinesterase activity did not increase proportionally to the concentration

of the juices. The activity decreased to a minimum at 41lBrix for the Duncan and

at 330Brix for the Valencia juices when calculated to the original Brix of these

two juices. The water-soluble pectin in the Duncan and Valencia juices gradually

decreased while the sodium hexametaphosphate fraction increased when calculated

to the original Brix of these two juices.

Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission
Lake Alfred, Florida
429t 6/9/53 AHR









TABLE 13
Effect of concentration on rate of clarification in Duncan grapefruit concentrates


Degree
of
concentration

OBrix Fold
10 1.1

18 2.0

25 2.9

34 3.9

41 4.9

53 i 6.7

61 7.9

75 j11.1


i Degree of clarificationI


Concentrates


Fresh
Jaice
79

79

78

80

77

77

78

75


tInitial
67

S 68


After
24 hr.
at 80F.
73
Slight
78
Slight
87
Definite
89
Definite
85
Definite
70
Slight
70
Slight
74
Slight


After storage at 400F.


l-wk.
75
Slight i
80
Definite
88
Definite
85
Definite
72
Slight
69
'None
68
None
72
Slight


2-wk.
76
Slight
82
Definite,
90
Extreme
91
Extreme
85
Definitely
71
Slight
69
None
70
Slight


3-wk.
76
Slight
85
Definite
92
Extreme
93
Extreme
89
Definite
74
Slight
70
Slight
69
None


1 Clarification measured by percentage light transmission of centrifuged
rectangular cell in"Lumetron colorimeter with Filter No. 730. Degree
70-79% = Slight; 80-89% = Definite; 90-100% = Extreme.
Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission
Lake Alfred, Florida
429v 6/10/53 AHR


1-mo.
76
Slight
86
Definite
92
Extreme
94
Extreme
89
Definite
78
Slight
70
Slight
69
None


2-mo.
80
Definite
87
Definite





91
Extreme
74
Slight
S72
Slight


reconstituted juic


of clarification:


3-mo.
80
Definite
85
Definite
-


-



76
Slight
71
Slight


e using 10 mt.
0-69% = None;


I


--


- -- ----









TABLE 14

Effect of concentration on rate of clarification in Valencia orange concentrates


Degree
of
concentration
Fol


oBrix
13

18

27

33

40

51

64

74

78


Fold
1.1

1.5


2.3

2.9

3.6

4.8

6.3

7.7

8.3


jDegree of clarification


i Concentrates


'Fresh
Juice
88

S91

91

90

92

91

92

92

89


!Initial
60

56

56

55

54

52

50

54
51


After
24 hr.
at 800F.
67
Slight
72
Definite
82
Definite
88
Extreme
88
Extreme
80
Definite
58
None
55
None
51
None


After storage at 40F.


i ---
Sl.-wk.
74
Definite
88
Extreme
93
Extreme
85
Extreme
83
Definite
174
IDefinite
53
None
54
None

i-


2;-wk.
84
Definite
93
Extreme
95
Extreme
90
Extreme
88
Extreme
80
Definite
55
None
56
None
-


3-wk.
86
Extreme
92
Extreme
95
Extreme
91
Extreme
88
Extreme
82
Definite
55
None
54
None


1 Clarification measured by percentage light transmission of centrifuged
rectangular cell in Lumetron colorimeter with Filter No. 730. Degree
60-6?9 = Slight; 70-84% = Definite; 85-100% = Extreme.
Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission
Lake Alfred. Florida
429w 6/10/53 AHR


1-.mo.
87
Extreme
93
Extreme
96
Extreme
93
Extreme
91
Extreme
85
Extreme
59
None
53
None
52
None


S2-mo.
S83
Definite








88
Extreme
65
Slight
54
None
53
None


reconstituted juice
of clarification:


3"-mo.
80
Definite
1-
I-





88
Extreme
76
Definite
56
None
54
None


e using 10 mm.
0-59% = None;


_ _i


- -








TABLE 15


Pectinesterase activity and pectin found in Duncan grapefruit juices at varying concentrations


Degree Concentrate 'I Calculated to 10OBrix
of cone. (PE.u.)g. Fectin-milligrams per 100 grams iJ (E.u,)g. Pectin-milligrams per 100 grams
oBrix conc.x104 water (IaP03)n NaOH total juicexl04 water (NaPO3)n NaOH total

10 9.4 11.3 8.3 9.5 29.1 9.4 11.3 8.3 9.5 29.1
18 14.1 17.6 15.5 15.9 49.0 7.6 9.5 8.4 8.6 26.5
25 17.3 22.2 23.1 22.8 68.1 6.9 8.8 .9.2 9.0 27.0
34 20.6 19.0 39.1 32.8 90.9 6.2 5.7 11.7 9.8 27.2
41 22.8 35.7 38.8 37.0 111.5 5.5 8.6 9.4 8.9 26.9
53 34.6 43.0 53.7 43.8 14/..5 6.6 8.2 10.2 8,3 26.7
61 36.0 29.8 67.9 55.3 153.0 6.1 5.1 11.5 9.4 26.0


Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
429x 6/10/53 AHR








TABLE 16


Pectinesterase activity and pectin found in Valencia juices at varying concentrations


SDegree Concentrate Calculated to 13Brix
of cone. (PE.u.)g. Pectin-milligrams per 100 grams (Pj.u.)g. Pectin-milligrans per 100 grains
OBrix conc.xlO4 water (NaPO3)n NaOH total iexl4 water (NaPO3)n NaOH total

13 10.0 9.6 11.1 11.0 31.7 10.0 9.6 11.1 11.0 31.7
18 13.3 11.7 16.9 15.1 43.7 9.9 8.6 12.5 11,2 32.3
27 18.7 17.4 23.8 21.0 62.2 f 9.2 8.5 11.6 10.3 30.4
33 20.3 21.5 30.0 26.8 78.3 7.9 8.5 11.7 10.4 30.6
40 26.6 19.5 48.7 34.1 102.3 I 8.7 6.4 15.9 11.1 33.4
51 34.3 25.5 61.0 44.7 131.2 1 8.8 6.5 15.6 11.4 33.5
64 42.2 31.6 70.4 50.9 152.9 8.7 6.5 14.6 10.5 31.6


Citrus Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Conmission,
Lake Alfred, Florida
429y 6/15/53 AHR








6. Effect of Storage Temperatures on Pectinesterase Retention in Citrus
Juices.


Valencia orange and Duncan grapefruit juices were placed in storage at 80F.,

40OF., and -8F. to determine enzyme losses at their natural pH. The results ob-

tained should be of importance to the analyst interested in assaying citrus juices

for their pectinesterase activity, since they indicate that orange and grapefruit

juices held for 3 hours at 800F. may lose as much as 6% and 35% of their enzyme

activity, respectively.

The deleterious effect of storage for 24 hours at 800F. in Valencia orange and

Duncan grapefruit juices is presented in Table 17 while the loss of pectinesterase

in these two varieties of juices stored at 400F. for varying intervals of time is

shown in Table 18. After 52 weeks of storage at -8F., the juices showed no appre-

ciable loss in activity. This is presented in Table 19.

The loss of pectinesterase activity in citrus juices decreased with decreased

storage temperatures.

Valencia orange juices containing 14% and 6% pulp, pH 3.7 and pH 3.8, when

stored at 800F. for 6 hours lost 21.8% and 10.7% of their enzyme activity, respec-

tively, while Duncan grapefruit juice containing 4.0% pulp, pH 3.4, lost 41.7% of

its activity under similar storage conditions.

At a storage temperature of 40F., pectinesterase activity in Valencia orange

juice decreased 14.6% in 7 days and 25.3% in 28 days, while the activity in Duncan

grapefruit juice decreased 33.3% and 56.8% in 7 an& 28 days, respectively.


Station Mimeo Report 54-1.
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred,' Florida
429z 6/15/53 AHR










TABLE 17


Loss of pectinesterase in citrus juices during storage at 800F.


-Valencia orange juice Duncan grapefruit juice
Storage Pulp content 14% Pulp content 6% Pulp content 4%
time pH 3.7 pH 3.8 pH 3.4
hours (PE.u.)g. Activity lost (PE.u.)g. Activity lost (PE.u.)g. Activity lost
X 104 % X 14 x 10
Immediate 50.4 None 8.4 None 13.2 None

1.5 48.8 3.2 8.1 3.6 10.4 21.2

3.0 46.1 8.5 7.9 6.0 8.6 34.9

4.5 42.3 16.1 7.8 7.1 8.2 37.9
6.0 39.4 21.8 7.5 10.7 7.7 41.7

24.0 42.6* 15.5 7.7* 8.3 4.1 68.9


Citrus Station limeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aa 6/18/53 AHR


* Yeast-like aroma


S -









TABLE 18

Loss of pectinesterase in citrus juices during storage at 400F.


Valencia orange juice Duncan grapefruit juice
Storage Pulp content 8r Pulp content 4l
time pH 4.1 pH 3.4


(PE.u.)g.
days X 104
Immediate 15.8

1 15.3

2 15.3

4 15.3

7 13.5

14 13.3
21 13.0

28 11.8
Citrus Station Kimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429ab 6/18/53 AHR


Activity lost (PE.u.g. Activity lost
% X 10%


None

3.2

3.2

3.2

14.6

15.8

17.7
25.3


13.2 None

10.1 23.5

8.8 33.3

8.8 33.3

8.8 33.3

8.7 34.1

6.5 50.8

5.7 56.8


*










TABLE 19

Retention of pectinesterase in citrus juices during storage at -80F.


Storage Valencia orange juice Duncan grapefruit juice
Pulp content 6.5% Pulp content 45
time pH 3.8 PH 3.4
weeks (PE.u.)g. Activity (FE.u.)g. Activity
X 10i gained or lost X 104 gained or lost


Imediate 11.1 None 12.1 None
2 11.7 +5.4 11.8 -4.9
4 10.7 -3.6 12.2 +0.8
6 11.0 -0.9 11.9 -1.7
8 10.5 -5.4 11.9 -1.7
16 10.5 ;-5.4 12.0 -0.8
20 10.6 -4.5 12.1 0.0
24 10.0 -9.9 10.9 -9.9
28 9.5 -14.4 11.2 -7.4
32 9.9 -10.8 12.0 -0.8
40 10.0 -9.9 12.3 +1.7
52 9.9. "-10.8 10.9 -9.9
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429ac 6/18/53 AHR





-31-


7. Clarification in Heat-Treated Pineapple orange Concentrates.

This study covered the results obtained from two investigations on heat-treat-

ment of Pineapple orange juices and concentrates. The first study was concerned

with the effect of heat-treatment of orange juice before concentration to 42OBrix

on pectinesterase activity, clarification and gelation during storage, and the de-

struction of microorganisms. The second investigation was undertaken to determine

the temperature necessary for both the initial heat-treatment of orange juice and

the final treatment of the concentrate in order that the hot-packed product could

be stored at 32oF. without appreciable deterioration of quality. Because of the

effect of heat-treatment on the flavor of the product, it is desirable that the

minimum amount of heat-treatment be used necessary for obtaining the desired pro-

duct stability.

Results reported in Table 20 show the effect of heat treatment of Pineapple

orange juice before concentration to 42oBrix on pectinesterase activity, clarifi-

cation and gelation after storage at 800F. for 24 hours, and destruction of micro-

organisms in the concentrate. Clarification and gelation were prevented in these

concentrates by heat treatment at 1650F. which brought about approximately 75% of

pectinesterase inactivation and also resulted in a very marked decrease in the mi-

croorganism count.

Data presented in Table 21 show the stability to clarification of the hot-pack-

ed concentrates during storage at 32F. over a period of 18 months. The results in-

dicate that final heat treatment of the 42oBrix concentrate at 185F. or 1950F. was

necessary to prevent clarification during storage at 320F. for one year. The effec-

tiveness of initial and final heat-treatments as a means of removing the last traces

of enzyme activity is shown. The initial heat-treatment of both raw and cut-back

juices in the range of 1900F, to 1950F. did not prevent clarification unless the
42Brix concentrate was also heated to 1950F.
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
429 ad 6/18/53 AHR










TABLE 20


Effect of heat treatment of Pineapple orange juice before concentration to 420
Brix on pectinesterase activity, clarification, gelatin, and micro-organism
count in the concentrateI


Pectinesterase activity Degree of clarification2 Degree of gelation Microorganism Count3
% inactivation after 24 hr. at 800F. after 24 hr. at 80F. X 1000
Temperature Pulp content Pulp content Pulp content Pulp content
oF. 5% 10% 15% 5% 10% 15% 5% 10% 15% 5% 10% 15%
Unheated
Control Definite Extreme Extreme None None Solid-gel 208.0 24.0 47.0
125 -- -. Definite Extreme Extreme None None Solid-gel 27.0 28.5 40.0
135 --- Definite Extreme Extreme None None Solid-gel 225.5 24.5 26.0
145 33 12 4 None Definite Extreme None None Semi-gel 13.0 18.0 85.0
155 50 32 34 None None Definite None None Slight 11.0 10.5 8.0
165 75 70 78 None None None None None None 2.6 3.5 2.2
175 87 96 96 None None None None None None 4.9 1.9 1.1
185 100 100 98 None None Definite None None None 9.2 7.5 5.7
195 100 100 100 None None None None None None 5.3 6.0 3.2
1 The concentrates did not contain any cut-back juice.
2 Clarification measured by percentage light transmission of centrifugal reconstituted juice using Fisher
Electrophotometer with Filter No. 650 and 23 ml. cylindrical cell. Degree of clarification: Less than
10% = None; 10-19% = Slight; 20-45% = Definite; 46-100% = Extreme.
3 Total count in reconstituted juice plated on dextrose agar, pH 7.


Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake-Alfred, Florida
429ae 6/18/53 AHR









TABLE 21

The relation of heat treatment to clarification of hot-packed Pineapple orange concentrate


Heat treatment Clarification during storage at 320F.
Juice prior Cut-back Concentrate 6 months 9 months 12 months 15 months 18 months
to concentration juice 42 Brix
oF oF OF..
160-165 160-165 165 Extreme Extreme Extreme --
I 175 Extreme Extreme Extreme ----
f 185 None None Extreme Extreme Extreme
S" 195 None None None None None
170-175 170-175 165 Extreme Extreme Extreme -- -
11 175 Extreme Extreme Extreme ----
185 Extreme Extreme Extreme --- --
S" 195 None None None None None
180-185 180-185 165 Extreme Extreme Extreme ---
I" 175 Extreme Extreme Extreme --
185 Extreme Extreme Extreme --
f 195 None None None None None

190-195 190-195 165 Extreme Extreme Extreme -- -
175 Extreme Extreme Extreme --
185 None None None Extreme Extreme
.." 195 None None None None None
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429af 6/18/53 AHR






-34-

8, Study of Flavor in Heated and Unheated Citrus Juices and Concentrates.

The first part of this discussion concerns the flavor of heated single-strength

juices while the last section concerns flavor comparison of concentrates in heated

and unheated juices. The flavor study on the concentrates is not completed because

storage studies are to be followed for one year, thus only initial flavors are given

for these 42OBrix concentrates.

Valencia oranges carefully selected with all poor quality fruit discarded were

extracted on a Rotary press. The extracted juice was run through a revolving 1/4

inch screen to remove seeds and coarse particles of pulp and finished through a 0.030

inch screen. The juice had a pulp content of 8%, an oil content of 0.017%, and a pH

4.1. By using a tubular hot-water pasteurizer, the single-strength juice samples

were heated under varying conditions and submitted to a small experienced taste

panel for flavor evaluation.

(a) In this series, temperatures and retention times were used that re-

sulted in 100% and 90% pectinesterase inactivation at pH 3.5 and pH 4.1. The heat-

ed juices were cooled by immediately flashing into a vacuum chamber.

Temperatures F. 210 210 210 205

Retention time Seconds 0.8 3 6 12

(b) In this series, a constant time of 12 seconds was used with tempera.

tures of 1450F., 165F., 1850F. and 2050F. After heating the juices were cooled

in 14 seconds through a water cooled coil.

(c) In this series, temperatures and retention times necessary for com-

plete inactivation, as in series (a), were used followed by different cooling pro-

cedures as follows:

Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429ag 6/18/53 AHR





-35-


(1) Dry ice-alcohol mixture

(2) Cooling water 14 seconds

(3) Cooling water 14 seconds then flashing into vacuum

(4) Flashed into vacuum immediately after heating.
Considering all the opinions expressed by the taste panel as well as the in-

dividual members' ability to separate correctly juice samples which had different

treatments, the following general conclusions were reached.

(a) For the consumer, there were no differences in the flavor of Valencia
orange juices at pH 3.5 and pH 4.1, when pectinesterase was inactivated at 90% and

100%, when the pasteurization retention times were 0.8, 3, 6, and 12 seconds and

when the juice was immediately flashed into vacuum for cooling.

(b) The important difference was in the pH of the juices, the juice with

pH 3.5 being more tart than the juice of pH 4.1.
(c) The trend favored the 3 and 0.8 seconds pasteurization times at either

pH 4.1 or pH 3.5 for either the 100% or 90% inactivation of the enzyme in the juices.

(d) Juices cooled with dry ice-alcohol mixture were the best flavored

ranking slightly better than the control.
(e) Juices cooled by flashing immediately into vacuum were in general the

poorest flavored because of the loss of volatile oils.

(f) Juices cooled with water in 14 seconds and also with water in 14

seconds and then flashed immediately into vacuum were intermediate in flavor.

(g) In general, panel members graded the 1450F. and 2050F. juices, heated
in 12 seconds and cooled with water in 14 seconds, equal to the control juice,

(h) Juices heated in 12 seconds and cooled with water in 14 seconds when

heated to 1450F., 1650F., 1850F., and 205F. gave no heated flavor when the juice

was properly prepared,
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
429ah 6/18/53 AHR





-36-


Concentrates were prepared from unheated and heated juices of Parson Brown,

Pineapple, and Valencia oranges and Dancy tangerines during the height of the

season for that particular variety when flavor in the fruit should be best. How-

ever, it is pointed out at this time that the taste panel rated these juices in-

itially, including the control, as fair.

The juice was extracted from the fruit as previously described resulting in

a juice containing 8% pulp content by volume. The pulpy residue was refinished by

passing through a 1/8 inch screen to give the cut-back juice. The pulp content of

the cut-back juice ranged from 25% by volume for Dancy tangerine to 50% for Pine-

apple orange juice.

The juice to the evaporator (8% pulp content) was pumped through 24 feet of

1/8 inch ID. stainless steel heating tube at a flow rate of 560 ml per minute.

Hot water was circulated around the heating tube to provide the desired tempera-

tures that would result iin approximately 0, 75, 90, and 100% inactivation of pec-

tinesterase. The time required to heat the juice from room temperature to the de-

sired temperature was 6 seconds. The juice was discharged directly from the heater

through 44 feet of 1/8 inch I.D. stainless steel cooling tube requiring 14.2 sec-

onds which cooled the heated juice to a temperature between 800 and 86oF. Water

circulating around the cooling tube ranged from 780 to 800F. Juice from the cool-

ing tube was flashed into the evaporator and concentrated to 550Brix.

In order to obtain the various percentages of pectinesterase inactivation the
following temperatures were used.
Inactivation 0.0% 75.0% 90.0% 100.0%
Oranges No heat 1550F. 1750F. 2050F.
Tangerines No heat 1500F. 1900F. 2000F.

Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429ai 6/18/53 AHR





-37-


The 550Brix concentrate was cut-back with unheated pulpy juice to 42OBrix con-
centrate, packed in 6-oz. cans and placed in -8F. storage.

A small taste panel of five members initially graded the samples of concen-

trates. After six and twelve months storage at -80F. the panel will again grade

the concentrates. The average initial grades of the unheated and heated reconsti-

tuted concentrates as given by the taste panel are presented in Table 22. A grade

of fair is numerically 5 to 7 inclusive and a grade of 4 or below is poor.
TABLE 22

Initial grades of 42Brix orange and tangerine concentrates processed for
flavor study in which unheated vs. heated juices were used.


Temp. of Initial grade of cone. Temp. of Initial grade of cone.
juice 6 sees. Parson.Brown Pineapple Valencia juice 6 sees. Dancy tangerine
No' heat 5.8 6.6 6.2 No heat 6.4
1550F. 4.6 6.0 7.0 155F. 5.4
1750F. 5.6 6.8 6.2 190F?. 5.8
2050F. 4.8 5.6 6.0 2000F. 5.2

Since the grades of the reconstituted concentrates fell into the fair cata-

gory there must be very little difference between the heated and unheated samples.

This was the general conclusion of the taste panel members that there were too small

differences between concentrates prepared from unheated and heated juices.

Other data are being obtained on these flavor packs, such as pectin changes

during processing and storage along with cloud and gelation observations. Samples

from the packed concentrates that have received heat treatment when placed in stor-

age for 24 hours at 80F. have neither gelled nor lost cloud. For example, the

initial cloud in Parson Brown concentrates when reconstituted showed no clarifica-

tion while the initial cloud on Pineapple concentrate showed slight clarification.

After 24 hours storage at 800F..the two orange packs had the same clarification as
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aj 6/18/53 AHR








they did initially. The lowest temperature used was 1550F. which reduced pectin-

esterase activity 75% in the juice to the evaporator, whereas 2050F. was the high-

est temperature applied to the juice to the evaporator which reduced the activity

100%. The small amount of data to date also indicates that juices heated to 155 F.

show very little conversion of water-soluble pectin to insoluble polyvalent pecti-

nates during processing. Although more data are needed this would also indicate

that by protecting the water-solitble pectin the cloud of the juice can be pre-

served.





























Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429ak 6/18/53 AHR





-39-


9. Maturity Study of Pineapple Oranges.

A maturity study as it affects processed concentrates, especially clarifica-

tion and gelation in correlation with pectinesterase and pectins, was run on Pine-

apple oranges for a period of five months starting with a low Brix-acid ratio of

10.5 and ending with a high ratio of 18.8.

Nine (Citra) Pineapple orange trees were selected and 32 oranges were picked

from each tree or a total of 288 oranges were obtained from the nine trees for each

determination. Four fruit were selected from the inside and four fruit from the

outside of each tree from top; to bottom and from four sides of a tree. The oranges

were washed, wiped dry, and peeled by hand to remove the flavedo and albedo. The

peeled fruit was placed in 320F. storage over night. The following morning it was

halved and finished once through a 0.020 inch screen Food Machinery Finisher, Model

35, loosely set. The residue was refinished. The two juices were combined giving

approximately 10 to 13% pulp by volume. The juice was concentrated to 550Brix and

cut-back to 42Brix concentrate with pulpy juice. The pulpy cut-back juice was

prepared by taking the residue remaining from the second finishing operation and

refinishing through a 1/8 inch screen. This juice would range in pulp content by

volume from 36 to 48%. Each month for five months the fruit was picked and pro-

cessed alike as nearly as possible.

Total solids, pectinesterase activity, and pectins were determined on the peel

(flavedo and albedo), pulp (rag and juice sacs), pulpy cut-back juice, juice to

evaporator, centrifuged juice, 550Brix concentrate, and the final 420Brix concen-

trate. Clarification and gelation were determined on the 420Brix concentrates

initially stored at -8F., and after short-term storage for 24 hours at 80F.

Maturity changes over a period of five months in Brix/acid ratio, total solids,
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429al 6/19/53 AHR






-40-
TABLE 23
Maturity changes in the component parts of (Citra) Pineapple oranges.


Component Brix/acid Total (PE.u.)g. Pectin as anhydrogalacturonic acid
part juice solids dry'basis dry basis
ratio % x 103 H20-sol. (NaP03)n-sol. NaOH-sol. Total

Peel 10.5 30.1 50.8 1.54 6.17 9.75 17.46
" 12.0 27.9 145.7 1.95 7.60 8.87 18.42
" 13.7 27.1 120.8 1.19 7.63 9.29 18.11
" 15.9 25.8 122.1 0.39 11.66 7.38 19.43
n 18.8 27.2 90.1 0.76 8.10 7.46 16.31
Pulp 10.5 14.4 322.9 0.90 1.90 4.91 7.71
" 12.0 15.0 302.1 1.19 1.94 4.95 8.08
" 13.7 15.4 325.9 1.08 2.34 3.66 7.08
" 15.9 15.4 439.5 1.34 2.83 3.09 7.26
" 18.8 16.1 327.6 0.43 2.21 2.88 5.51
Cut-back juice 10.5 12.6 126.3 1.15 0.90 2.28 4.33
12.0 13.3 160.8 1.14 0.95 2.27 4.36
13.7 13.8 180.8 1.14 1.15 1.82 4.11
15.9 13.8 194.4 1.02 1.23 1.65 3.90
S18.8 14.5 97.7 0.83 0.92 1.27 3.01
Evaporator juice 10.5 11.3 17.1 0.23 0.13 0.28 0.64
12.0 11.8 18.9 0.28 0.15 0.25 0.68
*" 13.7 13.0 19.8 0.23 0.20 0.26 0.69
15.9 12.7 19.2 0.19 0.19 0.23 0.61
18.8 13.6 14.3 0.20 0.16 0.20 0.56
Centrifuged juice 10.5 10.6 2.2 0.21 0.21
i" 12.0 11.6 1.1 0.21 - 0.21
13.7 12.7 0.8 0.23 -- 0.23
15.9 12.5 0.8 0.20 0.20
18.8 13.5 0.6 0.19 0.19


Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429am 6/19/53 AHR





-41-


TABLE 24

Analyses of the pectic substances during maturity in 55OBrix and 42Brix
Pineapple orange concentrates reported on a dry solids basis

55OBrix concentrate
Maturity Total (PE.u.)g. Pectin as anhdroalacturonic acid
Brix/acid solids X 1000 H20-sol. (NaP3)n-sol. NaOH-sol. Total
ratio % 1 %
10.5 54.8 14.7 0.19 0.24 0.22 0.65
12.0 52.4 17.8 0.09 0.30 0.32 0.71
13.7 55.9 18.2 0.14 0.26 0.25 0.65
15.9 55.4 16.6 0.14 0.24 0.22 0.60
18.8 58.7 12.2 0.16 0.19 0.19 0.54

42oBrix concentrate, initial
10.5 42.3 27.9 0.21 0.42 0.35 0.98
12.0 40.2 41.5 0.12 0.49 0.52 1.13
13.7 40.5 42.7 0.25 0.35 0.33 0.93
15.9 40.6 39.1 0.09 0.49 0.36 0.94
18.8 41.7 33.9 0.09 0.46 0.35 0.89

42oBrix concentrate after 24 hours storage at 800F.
10.5 42.1 25.8 0.09 0.55 0.39 1.03
12.0 42.0 31.0 0.10 0.62 0.43 1.15
13.7 40.5 33.8 0.08 0.50 0.33 0.91
15.9 41.5 34.3 0.06 0.56 0.32 0.93
18.8 40.6 27.1 0.06 0.57 0.30 0.94


Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429an 6/19/53 AHR





-42-


and pectic substances in the component parts of Pineapple oranges aro presented in

Tables 23 and 24. The Brix-acid ratio changed from 10.5 in December to 18.8 in

April. Total solids in the peel gradually decreased from 30.1 to 25.8% in four

months, whereas total solids in the pulp, cut-back juice, juice to evaporator, and

centrifuged juice increased as the ratio increased, On a dry solids basis, pectin-

esterase was highest in the pulp and least in the centrifuged juice, reaching its

highest activity the fourth month for the pulp and pulpy cut-back juice.

Pectin was determined as anhydrogalacturonic acid by using the carbazole-gal-

acturonic acid-sulfuric acid reaction (1) and divided into water soluble, sodium

hexametaphosphate soluble, and sodium hydroxide soluble fractions.

The general trend for total pectin was to decrease over the five month period

in all components except the centrifuged juice which remained constant, Table 23,

The sodium hydroxide fraction, better known as protopectin, decreased during the

maturity study in which case the sodium hexametaphosphate fraction or the insoluble

polyvalent pectates and pectinates gradually increased the first four months and

decreased in every case the fifth month. The results in general from Table 24 would

indicate that the pectins in the 550 and 420Brix concentrates processed from Pine-

apple oranges remained fairly constant during the five month maturity study with a

slight decrease in total pectin as the maturity ratio increased. Since pectinester-

ase activity is highest in the pulp content of oranges and grapefruit and may vary

somewhat during the maturity of the fruit, this enzyme is always a liability unless

the pulp content is reduced or the juice partially heat treated in order to reduce

its activity.

Clarification and gelation data on the 42OBrix Pineapple orange concentrates pro-

cessed during the five month maturity study are shown in Table 25.
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429ao 6/19/53 AHR






-43-

TABLE 25

Initial clarification and short-term storage effects on clarification and
gelation of 42oBrix Pineapple orange concentrates processed during a five
month maturity study


Maturity Degree of clarification Degree of gelation
Brix/acid Initial After 24 hours After 24 hours
ratio from -8F. at 800F. at 80F.
10.5 49 None 98 Extreme 3 Semi-gel
12.0 51 None 97 Extreme 3 Semi-gel
13.7 51 None 97 Extreme 3 Semi-gel
15.9 53 None 95 Extreme 3 Semi-gel
18.8 56 None 96 Extreme 3 Semi-gel


As the ratio changed in raw Pineapple orange juice from 10.5 to 18.8, the

degree of clarification of reconstituted 42Brix concentrates from -80F. storage

measured as percentage of light transmission (2) ranged from 49 to 56 which is

indicative of no clarification. However, when like samples were placed in 24

hours storage at 80F., extreme clarification and semi-gels were found in all

samples.

In conclusion the maturity study would indicate that as the Brix-acid ratio

increased from 10.5 to 18*8 there were no significant changes in the pectic frac-

tions that would concern the citrus processor. His main concern should be the

pectic changes during processing and storage, especially the loss of water-soluble

pectin which probably has a direct relationship to the "cloud" present in the con-

stituted juice.





Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429ap 6/19/53 AHR





-44-


10. Correlation of Pectic Substances and Related Factors with "Cloud"
Stability and Gelation in Citrus Juices and Concentrates.

This is a study that has just begun in an attempt to tie the various factors

together and correlate tham so that a stabile juice or concentrate may be processed.

It is also hoped that the degree of gelation in a citrus concentrate can be corre-

lated with the quantitative amount of pectin present either in the raw juice before

evaporation or in the finished product.

To begin this study packs of Pineapple and Valencia oranges and Duncan grape-

fruit have been prepared and placed in -8OF. storage. These packs received no heat

treatment. The Pineapple pack has been partly analyzed and some results are avail-

able.

The juice, pulp, and seeds were extracted from the fruit using a Citro-Mat ex-

tractor and thon passed through a Food Machinery Finisher using a 0.030 inch screen.

The juice passing through the 0.030 inch screen was again screened on a 165 mesh

shaker screen. This is called the base juice to which varying amounts of pulpy

juice were added. The juice, seeds, and pulp extruded from the finisher were again

finished with a 0.030 inch screen in order to prepare a pulpy juice. Finally both

juices were blended together to make single-strength juices with pulp content by

volume ranging from 2 to 24%. Samples of the single-strength juices were placed in

6 oz. cans and stored at -80F. while 2.5 gallons of each were concentrated to 420

Brix, placed in 6 oz. cans, and stored at -80F.

The data presented in Tables 26, 27, 28, and 29 are apart of the results ob-

tained from the Pineapple orange packs. Table 27 shows that as the pulp in the

juice is increased from 3 to 24% by volume the water-insoluble solids and pectin-

esterase activity also are increased proportionally. This table also shows that

Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aq 6/19/53 AHR









TABLE 26


Analyses of the blended juices and resulting concentrates before and
after storage for 24 hours, at 80OF.


Extracted juices Pulp by Total solids
Juice passing Juice passing centrifugal Single-strength 420Brix cone. 42Brix cone.
165 mesh screen 0.030 inch screen method juice initial after 24 hrs. 800F.
ml m al.. I%%%
12,000 3.0 11.9 40.6 41.3
9,800 2,200 7.0 12.0 41.7 42.3
8,00 3800 9.0 12.1 40.6 42.0
6j500 5,500 12.0 12.1 41.5 42.3
4,900 7,100 16.0 12.2 42.0 42.7
3,306 84700 19.0 12.3 42.1 42.7
1,600.. 10,400 21.0 12.3 42.4 42.9
- 12,000 24,0 12.4 42.0 42.8


Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429ar 6/19/53 AHR










TABLE 27


Relationship of pulp to water-insoluble solids and to pectinesterase activity
in the juice and concentrates of Pineapple oranges


Pulp by
centrifugal
method


Water-insoluble
Single-strength
juice


solids (dry weight basis)
42oBrix cone. 42oBrix cone.
Initial after 24 hrs.,800F.


PE activity per gram (dry weight basis)
Single-strength 42Bri con. Bx con. Brx cone.
juice Initial after 24 hrs.,800F.


%, % % xl0-3 xlO-3 x10-3
3.0 0.61 0.60 0.89 5.0 5.3 4.4
7.0 1.14 1.22 2.09 27.1 26.6 23.6
9.0 1.52 2.30 2.86 39.7 39.6 35.7
12.0 1.81 2.49 3.43 58.6 56.1 49.7
16.0 2.17 2.98 3.70 82.0 76.3 73.8
19.0 2.65 3.67 4.52 98.7 90.0 77.2
21.0 3.03 4.08 5.09 113.0 109.6 89.7
24.0 3.29 4.79 5.46 127.0 125.9 108.7


Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429as 6/20/53 AHR


II I II I I I I I II I I I I I








TABLE 28


Percentage of the various pectic fractions present of the total pectin
found in juices and concentrates from Pineapple oranges pH 3.8


Pulp by Single-strength juice 42Brix cone., initial 42oBrix cone., after 24 hrs.800F.
centrifugal H20-sol. (NaPO3)n-sol. NaOH-sol. H20-sol. (NaPO3)n-sol. NaOH-sol. H20-sol. (NaP03)n-sol. NaOH-sol.
method
% % % % % % %
3.0 50.0 36.4 13.6 23.0 56.3 20.7 16.5 57.2 26.3
7.0 36.1 27.9 36.0 19.2 46.2 34.6 7.8 58.7 33.5
9.0 31.9 29.8 38.3 10.4 51.8 37.8 6.6 57.9 35.5
12.0 33.1 27.1 39.8 7.7 53.3 39.0 6.0 56.0 38.0
16.0 31.5 25.2 43.3 11.2 47.1 41.7 6.2 56.0 37.8
19.0 28.7 28.1 43.2 8.2 49.5 42.3 5.0 54.6 40.4
21.0 28.7 31.8 39.5 8.1 47.7 44.2 5.0 51.8 43.2
24.0 28.4 28.8 42.8 8.9 45.9 45.2 4.1 53.8 42.1


Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Carmission,
Lake Alfred, Florida
429at 6/20/53 AHR









TABLE 29

Relationship of the combined water-soluble and sodium hexametaphosphate pectic
fraction to gelation and clarification in Pineapple orange concentrates,


Pulp by
centrifugal
method


3.0

7.0

9.0

12.0

16.0

19.0

21.0

24.0


420Brix concentrate, initial 42Brix cone. after 24 hrs., storage at 800F.
Pectin Part of Clarification Gelation Pectin Part of Clarification Gelation
wet basis total pectin wet basis total pectin


0.069

0.136

0.186

0.2/7

0.282

0.337

0.378

0.421


79.3

65.4

62.2

61.0

58.3

57.7

55.8

54.7


None

None

None

None

Slight

Slight

Definite

Definite


None

None

Very
slight
Very
slight
Very
slight
Slight

Slight

Slight


0.067

0.145

0.205

0.260

0.320

0.359

0.397

0.453


73.6

66.5

64.5

61.9

62.1

59.5

56.8

57.9


Slight

Extreme

Extreme

Extreme

Extreme

Extreme

Extreme

Extreme


None

Very slight

Slight

Semi-gel

Semi-gel

Semi-gel

Semi-gel

Semi-gel


Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429au 6/20/53 AHR


--


c


CirsStto -moRpot 5-







-49-

there is an increase on dry weight basis of water-insoluble solids during pro-

cessing and storage after 24 hours at 80OF. For example, the juice showing a

pulp content of 12% increased in water-insoluble solids from 1.81% to 2.49% to

3.43% and this increase resulted from the formation of insoluble polyvalent pec-

tates and pectinates as pectinesterase demethylated the pectin during processing

and storage. Data in Table 28 further indicated and confirmed the data of Table

27, that during processing there is an increase in the sodium hexametaphosphate

pectic extraction better known as the low methoxyl pectinic acids as polyvalent

insoluble pectinates. Furthermore, there is also an increase of this pectic frac-

tion during storage for 24 hours at 800F. Stated briefly the data presented show

that during processing and storage the water-soluble pectin decreased while the

poly-phosphate fraction increased.

Table 29 shows the relationship between the combined water and poly-phosphate

pectic fractions found initially in 42OBrix concentrate and after this concentrate

has been stored for 24 hours at 80aF. along with the degree of gelation and clari.

fiction. Degree of gelation is indicated as none, very slight, slight, semi-gel,

and solid gel (3, 4). Since this is preliminary data the range of pectin to degree

of gelation is not predicted at this time.










Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429av 6/19/53 AHR






-50-


11. The Effect of Heat Treatment in the Survival of Microorganisms in
Single-Strength and Concentrated Orange Juice

The experiments summarized in this report are continuations of two preliminary

experiments reported in the Progress Report of June 30, 1952. It was thought to be

pertinent to collect more data relative to the survival of Lactobacillus plantarum
and Leuconostoc mesenteroides in juices from a variety 6f fruit gathered at inter-

vals during the season. The survival of L. plantarum in Pineapple orange juices

with pH 3.8 and 3.6, and also in Valencia orange juices of pH 3.6 and 3.7, has been

determined by heating from 1350F. to 185F. in 0.8, 3, 6, and 12 seconds and the data

are presented in Tables 30 and 31. The thermal death points in the Pineapple juice,

pH 3.8, were 1750F. at 0.8 and 3 seconds; with temperatures of 1650F. and 1550F.
for the 6 and 12 seconds heating times, respectively. In the Pineapple orange juice,

pH 3.6, the microorganisms were inactivated at 1650F. in 0.8, 3, and 6 seconds, and
1550F. in 12 seconds heating time. In Valencia orange juice data presented in Table
32, the microorganisms were inactivated at 1650F. in 0.8, 3, and 6 seconds, and 1550F.

at 12 and 6 second intervals with pH 3.6. The thermal death points of L. mesenter-
oides in the Pineapple orange juices, pH 3.6 and 3.8, and Valencia orange juice pH

3.7, were 155F- in 0.8 and 3 seconds and 1450F. for 6 and 12 seconds as indicated
in Tables 33, 34, and 35.
The survival of unidentified organisms in grove run fruit without the addition

of specific inocula has been determined on Pineapple orange juice. The juice, pH

3.8, was extracted and heated to temperatures of 1450F. to 1900F. in 0.8, 3, 6 and

12 seconds. The freshly extracted juice contained 65,000 to 74,000 microorganisms

per ml. Results reported in Table 36 indicate complete inactivation at 1550F. for

Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aw 6/22/53 AHR









12 seconds and 1650F. at 0.8, 3, and 6 seconds heating intervals.
Specific strains of microorganisms were added to Pineapple orange juice, pH

3.9, and concentrated to 2, 3, and 4-fold. The concentrates containing 100,000 to

200,000 microorganisms per ml. were heated from 1450F. to 1850F. in 3, 6, and 12

seconds. The data are presented in Tables 37, 38, and 39. Commercially acceptable

pasteurization in 3, 6, and 12 seconds was at temperatures of 1750F., 165F., and

145FP., respectively in the 2-fold; with inactivation at 1650F. in the 3-fold and
4-fold concentrates for all three heating intervals.


Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429ax 6/22/53 AHR









TABLE 30


Effect of temperature and time exposures on the inactivation of Lactobacillus plantarum
in Pineapple orange juice, pH 3.8


Temp. Exposure Dilution Media
Times Numbers per ml. of juice
oF. Sec. Dextrose Agar Orange serum agar
pH 8.0 pH 5.6
None None 1:10,000 250,000 200,000
185 0.8 0 2 2
3.0 0 0 0
6.0 0 0 0
12.0 0 0 0

175 0.8 0 0 0
3.0 0 0 0
6.0 0 2 0
12.0 0 0 0
165 0.8 0 420 350
3.0 0 630 840
6.0 0 0 0
12.0 0 0 0
155 0.8 1:10 9q$00 9,100
3.0 1:10 9,450 10,500
6.0 1:10 60 30
12.0 1:10 0 0

Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission
Lake Alfred, Florida
429ay 6/22/53 AHR








TABLE 31


Effect of temperature and time exposures on the inactivation of Lactobacillus plantarum


in Pineapple


orange juice at pH 3.6


Temp. Exposure Dilution Media
OF. Times Numbers per ml. of juice
Sec. Dextrose agar Orange serum agar
.pH 7.0 pH 5.6
None None 1:100,000 400,000 400,000
185 0.8 0 5 3
3.0 0 3 3
6.0 0 2 3
12.0 0 2 2
175 0.8 0 2 3
3.0 0 2 3
6.0 0 2 3
12.0 0 1 2
165 0.8 0 1 1
3.0 0 7 4
6.0 0 2 1
12.0 0 1 0
155 0.8 0 TNTC TNTC
0.8 1:100 0 0
3.0 1:100 35,000 36,000
6.0 1:100 10,000 8,000
12.0 1:100 12,000 0
STNITC = Too numerous to count
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission
Lake Alfred, Florida
429az 6/22/53 AHR


I :
U'
i-


-L I









TABLE 32
Effect of temperature and time exposures on the inactivation of Lactobacillus plantarum


in Valencia orange juice at pH 3.6


Temp.


None
1850F.



175F.


Exposure
times
Sec.


None
0.8
3.0
6.0
12.0
0.8
3.0
6.0
12.0


1650F, 0.8
3.0
6.0
12.0
1550F. 0.8
3.0
6.0
12.0
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aaa 6/22/53 AHR


Dilution


Media
Numbers ter ml of iuice


Dextrose agar
pH 7.0


1 1000
0
0


612,000
0
0


0
0
0
0
20,400
6,800
0
0


Orange serum agar
pH 5.6
544,000
0
0
0
0


0
0
0
0
24,480
109200
0
0


Numbrs rr m of uic








TABLE 33


Effect of temperature and time


exposures on the inactivation of Leuconostoc mesenteroides in


Pineapple orange juice at pH 3.6


Temp.


Exposure
Times
Sec.


Dilution


Numbers per ml. of juice


Dextrose agar
pH 7.0


Orange serum agar
pH 5.6


None


None
0.8
3.0
6.0
12.0
0.8
3.0
6.0
12.0


155


145 0.8
3.0
6.0
12.0
135 0.8
3.0
6.0
12.0
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aab 6/22/53 AHR


1:100,000
1:10
1:10
1:10
1:10
1:10
1:10
1:10
1:10


1:1,000
1:1,000
1:1,000
1:1,000
1:1,000
1:1,000
1:1,000
1:1,000


3,200,000
0
0
0
0


44,000
6,000
0
0
.7,000
50,000
6,000
1,000


3,000,000
0
0
0
0


30,000
7,000
0
0
11,000
25,000
4,000
3,000


!
!l
IU'


--


-- -


- ---~-


--










tmerature and time


TABLE 34
exposures on the inactivation of lauconostoo m n


Pineapple orange juice, pH 3.8


Temp. Exposure Dilution Media
Times Numbers per ml. of juice
OF. Sec. Dextrose agar Orange serum agar
pH 7.0 pH 5.6
Nohe None 1:10,000 360,000 310,000
165 0.8 0 0 0
3.0 0 0 0
6.0 0 0 0
12.0 0 0 0
155 0.8 0 0 0
3.0 0 0 0
6.0 0 0 0
12.0 0 0 0
145 0.8 1:1,000 120,000 60,000
3.0 1:100 24,800 5,000
6.0 1:100 0 0
12.0 1:100 0 .0
135 0.8 1:1,000 242,000 95;000
3.0 1:1,000 57,000 30,000
6.0 1:1,000 10,000 8,000
12.0 1:100 500 600
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aac 6/22/53 AHR


Eff








TABLE 35


Effect of temperature and time


exposures on the inactivation of Leuconostoc mesenteroides in
Valencia orange juice at pH 3.7,


Temp. Exposure Dilution Media
Times Numbers per ml. of juice
OF. Sec. Dextrose agar Orange serum agar
pH 7.0 pH 5.6
None None 1 10,000 180,000 200,000
165 0.8 1 10 40 0
3.0 1 10 10 0
6.0 0 0 0
12.0 0 0 0
155 0.8 0 0 0
3.0 0 0 0
6.0 0 0 0
12.0 0 0 0
145 0.8 1-100 0 200
3.0 1-100 0 100
6.0 1 100 100 0
12.0 1 100 -150 ... 0
135 0.8 1 100 54,400 42000
3.0 1 1,000 9,000 10,000
6.0 1 -100 1,800 1i-00
12.0 1 100 0 100
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aad 6/22/53 AHR






TABLE 36


Effect of temperature and
Pineapple


time exposures on the inactivation of microorganisms in
orange juice from grove-run fruit, pH 3.8


Temp. Exposure Dilution Media
Times Numbers per ml. of juice
OF. Sec. Dextrose agar Orange serum agar
pH 7.0 pH 5.6
None None 1:1,000 74,000 65,000
190 0.8 0 110 90
3.0 0 0 1
6.0 0 3 2
12.0 0 2 1
185 0.8 0 4 4
3.0 0 3 1
6.0 0 0 0
12.0 0 3 1
175 0.8 0 3 3
3.0 0 1 1
6.0 0 0 1
12.0 0 2 0
165 0.8 0 1 1
3.0 0 0 0
6.0 0 3 0
12.0 0 1 3
155 0.8 1:10 850 500
3.0 1:10 1,820 840
6.0 1:10 120 40
12.0 1:10 -.20 .0
145 0.8 1:100 12,500 4,500
3.0 1:100 13,200 5,000
6.0 1:100 9,200 5,300
12.0 1:100 5,000 2,600
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
lake Alfred, Florida
429aae 6/;2/53 ABR


I :F
I,







TABLE 37


Effect of temperature and'exposure times on the
trate prepared from grove-run Pineapple oranges
phase,


inactivation of microorganisms in two fold concen-
containing some added culture in the active growth
pH 3.9


Temp. Exposure Dilution Media
Times Numbers per ml. of reconstituted juice
F. Sec. Dextrose agar Orange serum agar
pH 7.0 pH 5.6
None None 1:10,000 100,000 90,000
185 3.0 1:10 200 0
6.0 1:10 250 0
12.0 1:10 250 0
175 3.0 1:10 400 0
6.0 1:10 230 0
12.0 1:10 250 20
165 3.0 1:10 220 120
6.0 1:10 320 0
12.0 1:10 310 10
155 3.0 1:100 1,250 1,250
6.0 1:100 900 250
12.0 1:100 850 0
145 3.0 1:1,000 10,000 10,000
6.0 1:100 4,500 4,000
12.0 1:100 2,500 0
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aaf 6/22/53 AHR








TABLE 38


Effect of temperature and exposure times on the inactivation of Microorganisms in three fold concen-
trate prepared from grove-run Pineapple oranges containing some added culture in the active growth
phase, pH 3.9

Temp. Exposure Dilutions Media
Times Numbers per ml. of reconstituted juice
*F. Sec. Dextrose agar Orange serum agar
pH. 7.0 pH. 5.6
None None 1:100,000 100,000 100,000
185 3.0 1:10 80 0
6.0 1:10 80 0
12.0 1:10 90 0
175 3.0 1:10 60 0
6.0 1:10 70 0
12.0 1:10 100 0
165 3,0 1:10 70 10
6.0 1:10 0 0
12.0 1:10 60 0
155 3.0 1:10 1,090 660
6.0 1:100 500 530
12.0 1:100 200 .260
145 3.0 1:100 5,560 38,400
6.0 1:100 28,230 50,000
12.0 1:100 6,660 6,330
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aag 6/23/53 AHR









TABLE 39


Effect of temperature and exposure times on the inactivation of Microorganisms in four fold concen-
trate prepared from grove-run Pineapple oranges containing some added culture in the active growth
phase, pH 3.9


Temp. Exposure Dilution Media
Times Numbers per ml. of reconstituted juice
oF. Sec. Dextrose agar Orange serum agar
pH 7.0 pH. 5.6
None None 1:10,000 200,000 180,000
185 3.0 1:10 30 40
6.0 1:10 30 0
12.0 1:10 50 0
175 3.0 1:10 10 0
6.0 1:10 10 0
12.0 1:10 10 0
165 3.0 1:100 60 0
6.0 1:100 20 0
12.0 1:10 20 0
155 3.0 1:10 2,310 2,880
6.0 1:10 320 360
12.0 1:10 150 90
145 3.0 1:100 4,700 3,900
6.0 1:10 6,920 5,960
12.0 1:10 6,350 5,190
Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aah 6/23/53 AHR


a,
I-
3






-62-


12. Outline for the Coming Season (1953-54)

1. To complete the time-temperature-fold relationships for heat inactiva-

tion of pectinesterase in citrus juices and concentrates.

a) Valencia orange juice, pH 4.0, folded 1, 2, 3, and 4 times and

heat treated at temperatures from 1250F. to 210F. for 3, 6,

and 12 seconds.

b) Duncan grapefruit juices at pH 3.3 and 3.8, Same as above.

a) To determine the "cloud" as percentage of light transmission on

the .-folded juices initially and after 24 hours storage at 800F.

when heated for 6 seconds from 1250F. to 2100F.

2. To complete the analyses on the flavor packs.

a) Taste panel to grade the flavor of the heated and unheated juices

after 6 and 12 months storage at -8F.

b) Pectin and pectinesterase analyses during processing and storage

on the heated and unheated packs which are now stored at -8F.

3. Flavor and Storage studies on heat treated juices and concentrates.

This part of the project is not to be confused with 2 above which was

done on a small scale and is preliminary to this large scale study which

is complete in itself. Packs for flavor and storage studies are to be

turned over to the leaders of these projects.

a) Variety Parson Brown, Pineapple, Valencia oranges, and Duncan

grapefruit.

b) Levels of pectinesterase inactivation 0, 50, 75, and 100%.

c) Inactivation at 1, 2, 3, and 4-folds.

Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aai 6/23/53 AHR









d) Concentrated to 55Brix and cut-back with unheated juice to 420Brix.

e) Heating time 6 seconds and juices to be cooled immediately either by

flashing under vacuum or cooling with water.

f) Flavor studies grading of concentrates by large taste panel.

g) Storage studies for clarification and gelation at -8F., O0F.,

100F., 200F., and 400F.

4. Correlation of the quantitative content of pectic fractions to degree of

gelation in citrus concentrates.

a) Varieties Pineapple, Valencia oranges, and Duncan grapefruit.

b) Range of pulp content from approximately 2 to 24% by volume.

c) Juices concentrated to 42Brix and placed in 24 hour storage at

800F. Degree of gelation and clarification recorded.

d) The three pectic fractions determined in the juice before evaporation,

after concentration to 420Brix and finally after 80F. storage for

24 hours.

5. Correlation of pectic substances and related factors to "cloud" stability

in citrus juices and concentrates.

a) Varieties Pineapple, Valencia oranges, Dancy tangerine, and Duncan

grapefruit.

b) Finishing Effect of quantity and particle size of water-insoluble

solids also called percentage of pulp content by volume.

c) Heat treatment percentage of pectinesterase activity.

d) Characterization of pectins in order to determine which is responsi-

ble for "cloud" and the amount necessary to produce a good "cloud".

Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aaj 6/23/53 AHR






-64-


e) Concentration or processing.

f) Storage to determine stability of "cloud".

6. Correlation of "cloud" to pectin content as a means of measuring water-

soluble pectin if water-soluble pectin is found in the above analyses to

be the "cloud" stabilizer. The use of percent light transmission, as an

index of water-soluble pectin which when plotted with pectinesterase activ-

ity would determine gelation in advance.

a) Varieties Pineapple, Valencia oranges, and Duncan grapefruit.

b) Compare percentage of light transmission with water-soluble pectin

and determine pectinesterase activity at partial inactivation.

7. Continuation of pectinesterase inactivation by hbat*treatment.

a) Changes in equipment.























Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aak 6/23/53 AHR







-65-


13. Literature Cited.

1. Dietz, J. H. and A. H. Rouse. A rapid method for estimating pectic sub-

stances in citrus juices. Food Research 18: 169-177. (1953).

2. Huggart, R. L., E. L. Moore, and F. W. Wenzel. The measurement of clari-

fication in concentrated citrus juices. Proc. Florida State Hort. Soc. 64th Ann,

Meeting. 185-188. (1951).

3. Rouse, A. H. Gel formation in frozen citrus concentrates thawed and stori

at 400F. Proc, Florida State Hort. Soc. 170-173. (1949).

4. Olsen, R. W., R. L. Huggart, and Dorothy M. Asbell. Gelation and clari-

fication in concentrated citrus juices. II. Effect of quantity of pulp in con-

centrate made from seedy varieties of fruit. Food Technol. 5: 530-533. (1951),























Citrus Station Mimeo Report 54-1
Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida
429aal 6/23/53 AHR