Group Title: Citrus Station mimeo report - Florida Citrus Experiment Station ; 54-6
Title: Effect of heat treatment on the survival of microorganisms in single strength and concentrated orange juices
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Permanent Link: http://ufdc.ufl.edu/UF00072353/00001
 Material Information
Title: Effect of heat treatment on the survival of microorganisms in single strength and concentrated orange juices
Series Title: Citrus Station mimeo report
Physical Description: 2, 9 leaves : ; 28 cm.
Language: English
Creator: Patrick, Roger
Hill, Elmer C
Citrus Experiment Station (Lake Alfred, Fla.)
Florida Citrus Commission
American Can Company
Publisher: Florida Citrus Experiment Station :
Florida Citrus Commission
Place of Publication: Lake Alfred FL
Publication Date: 1954
 Subjects
Subject: Orange juice -- Microbiology -- Florida   ( lcsh )
Concentrated fruit juices -- Preservation -- Florida   ( lcsh )
Microorganisms -- Control -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: Roger Patrick and E.C. Hill.
General Note: Caption title.
General Note: "American Can Company cooperating through establishment of grant-in-aid."
 Record Information
Bibliographic ID: UF00072353
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 74148652

Full Text


Effect of Heat Treatment on the Survival of Microorganisms in Single
Strength and Concentrated Orange Juices*
Roger Patrick and E. C. Hill


The destruction of spoilage organisms in citrus juices can be accomplished
by heat treatment. The results of a preliminary investigation reported at the
Third Annual Processors Meeting in qctober 1952, indicated that the destruction
of Lactobacillus plantarum in orange juice, pH 3.7, occurred between 1650F. and
1750F.; the destruction of Leuconostoc mesenteroides in orange juice, pH 3.7,
occurred between 1450F. and 15SSF. with complete destruction of the two species
when heated for 0.8 sec. at 1750F. and 1550F., respectively.

It was thought pertinent to collect more data relative to the survival of
microorganisms in single-strength juice and concentrates, when subjected to heat
treatment and flash cooling using the pilot plant pasteurizer that had been built
for the pectinesterase inactivation studies. The experiments were conducted dur-
ing the past season using Pineapple and Valencia oranges. The temperatures ranged
from 1350F. to 1900F. and the time exposures were 0.8, 3, 6, and 12 sec.

Single-strength juice was pasteurized and inoculated with identified strains
of L, plantarim and L. mesenteroides. Tables 1, 2, 3, and 4 contain the results.
Pasteurized single-strength juices, pH 3.6, 3.8, and 4.0, inoculated with L.
plantarum and exposed to 1650F. for 12 sec. yielded almost complete destruction
of the culture; pH did not seem to effect much change. L. mesenteroides exposed
at 1550F. for 12 sec. in similar juice under similar circumstances was destroyed
except at pH 4.0 when 12 sec. at 1650F. were required.

The effect of heat treatment was also determined in single-strength juice from
grove-run fruit. The juice carried a natural contamination with a supplement of
unidentified mixed laboratory culture or juice from cull fruit. The results are
given in Tables 5 and 6. Single-strength juice prepared from grove-run fruit at
pH 3.8 and 4.0 did not show complete destruction of the microbiological contami-
nation at 1900F. for 12 sec. Maybe those organisms surviving are not significant
and may be considered commercially acceptable. However, the numbers surviving
at pH 4.0 may not be due td the effect of pH alone, but also to the difference in
the microbiological contamination.
Two, three and four-fold concentrates were made from juice of grove-run
fruit as stated just previously; also from grove-run fruit that had been held in
storage and showed marked deterioration. This fruit was not culled carefully and
only the soft-rots were discarded. The results are listed injTables 7, 8, and 9.
Concentrates, pH 3.9 (Tables 7 and 9), prepared from grove-i friuitin 2, 3, and
4-folds when subjected to heat treatment did not show copleAe d tri'tion of
organisms at 1850F. for 12 sec.; however, the exposure may be cdnidered\commer-
cially acceptable, in that, no organisms or only a few grew on inoculated\plates
of orange serum agar. Similar concentrates, pH 3.8 (T ble 8), add showicomplete
destruction of organisms in the 3-fold product when expbsed for>12 seconds at
1850F., but the numbers surviving in 2-fold and 4-fold may\not considered of
much significance. Similar results were obtained for concehtrates,-pH ~3.9
(Table 9), with acceptable results designated at 1850F., 175f.', _and i650F. in
12 sec.

*American Can Company cooperating through establishment of grant-in-aid.

Citrus Station Mimeo Report 54-6. Florida Citrus Experiment Station and Florida
Citrus Commission, Lake Alfred, Florida. 464-10/6/53 RP





-2-


The tests, where a mixture of organisms were used in the juice and concen-
trates from grove-run oranges, did not show the consistently clear-cut results
after heat treatment that was noted in the experiments using pasteurized juice
inoculated with one strain of a bacterial species. The character of the microbial
contamination, rather than the pH of the juice, seemed to have more to do with
the numbers of organisms surviving. The numbers of organisms surviving may not
be significant when considering the stability of the juice, but such results
usually raise a doubt as to the quality of the fruit used,












































Citrus Station Mimeo Report 54-6. Florida Citrus Experiment Station and Florida
Citrus Commission, lake Alfred, Florida. 464-10/6/53 RP







TABIE 1


Effect of


heat treatment on the destruction of Lactobacillus
plantarum in Pineapple orange juice


Exposure Nunbers per al. of juice
Temp time Dextrose tryptone agar, pH 7.0 Orange serum agar, pH 5.6
OFSec. Juice, pH 3.6 Juice, pH 3.8 Juice, pH 3.6 Juice, pH 3.8

None None 400,000 250,000 400,000 200,000

185 0.8 5 2 3 2
3.0 3 0 3 0
6.0 2 0 3 0
12.0 2 0 2 0

175 0.8 2 0 3 0
3.0 2 0 3 0
6.0 2 2 3 0
12.0 1 0 2 0

165 0.8 1 420 1 350
3.0 7 630 4 840
6.0 2 0 1 0
12.0 1 0 0 0

155 0.8 TITC a 9,800 TNTC a 9,100
3.0 35,000 9,450 36,000 10,500
6.0 10,000 60 8,000 30
12.0 0 0 0 0

a TNTC = Too numerous to count


Citrus Station Mimeo Report 54 6. Florida Citrus Experiment Station and
Commission, Lake Alfred, Florida. 462-10/6/53 RP


Florida Citrus









TABLE 2


Effect of


heat treatment
plantarum in


on the destruction of Lactobacillus
Valencia orange juice


Exposure Numbers per ml. of juice
Temp. time Dextrose tryptone agar, pH 7.0 Orange serum rnar, pH 5.6
*F Sec. Juice, pH 3.6 Juice, pH 4.0 Juice, pH 3.6 Juice, pH 4.0

None None 480,000 300,000 460,000 370,000

185 0.8 0 0 0 0
3.0 0 60 0 0
6.0 0 0 0 0
12.0 0 0 0 0

175 0.8 0 0 0 0
3.0 0 0 0 0
6.0 60 0 0 0
12.0 0 30 0 0

165 0.8 0 0 0 0
3.0 0 10 0 0
6.0 0 40 0 0
12.0 0 0 0 0

155 0.8 6,100 0 5,400 70,000
3.0 1,300 35,000 1,100 35,000
6.0 0 3,500 0 80
12.0 0 0 0 0


Citrus Station Mimeo Report 54 6.
Commission, Lake Alfred, Florida.


Florida Citrus Experiment Station and
462a-10/6/53 RP


Florida Citrus









TABIE 3


Effect of heat treatment on the destruction
mesenteroides in Pineapple orange


of Ieuconostoc
juice


e Exposure Numbers per ml. of juice
oF. time Dextrose tryptone agar, pH 7.0 Orange serum agar, pH 5.6
Sec. Juice, pH 3.6 Juice, pH 3.8 Juice, pH 3.6 Juice, pH 3.8

None None 3,200,000 360,000 3,000,000 310,000

165 0.8 0 0 0 0
3,0 0 0 0 0
6.0 0 0 0 0
12.0 0 0 0 0

155 0.8 0 0 0 0
3.0 0 0 0 0
6.0 0 0 0 0
12.0 0 0 0 0

145 0.8 44,000 120,000 30,000 60,000
3.0 6,000 24,800 7,000 5,000
6.0 0 0 0 0
12.0 0 0 0 0
135 0.8 7,000 242,000 11,000 95,000
3.0 50,000 57,000 25,000 30,000
6.0 6,000 10,000 4,000 8,000
12.0 1,000 500 3,000 600


Florida Citrus


Citrus Station fMimeo Report 54 6. Florida Citrus Experiment Station and
Commission, Lake Alfred, Florida. 462b-10/6/53 RP








TABLE 4


Effect of heat treatment on the destruction of Leuconostoc
mesenteroides in Valencia orange juice


Temp. Exposure Numbers per ml. of juice
time Dextrose tryptone agar, pH 7.0 Orange serum agar, pH 5.6
Sec. Juice, pH 3.7 Juice, pH 4.0 Juice, pH 3.7 Juice, pH 4.0

None None 180,000 140,000 200,000 140,000

165 0.8 40 0 0 .
3.0 10 0 0 0
6.0 0 400 0 200
12.0 0 0 0 0

155 0.8 0 600 0 1,050
3.0 0 20 0 250
6.0 0 70 0 140
12.0 0 30 0 140

145 0.8 0 3,000 200 1,700
3.0 0 2,200 100 600
6.0 100 0 0 0
12.0 150 0 0 250

135 0.8 54,400 23,000 42,000 8;000
3.0 6,700 8,000 4,000 3,200
6.0 1,800 300 1,000 1,500
12.0 0 0 100 200


Florida Citrus


Citrus Station Mimeo Report 54 6. Florida Citrus Experiment Station and
Commission, Lake Alfred, Florida. 462c-10/6/53 RP






TABLE 5

Effect of heat treatment on the destruction of microorganisms in
Pineapple orange juice from grove-run fruit pH 3.8 D


Exposure Numbers per ml. of juice
Tep, time Dextrose tryptone Orange serum
F Sec. agar, pH 7.0 agar, pH 5.6

None None 74,000 65,000
190 0.8 110 90
3.0 0 1
6.0 3 2
12.0 2 1
185 0.8. 4 4
3.0 3 1
6.0 0 0
12.0 3 1
175 0.8 3 3
3.0 1 1
6.0 0 1
12.0 2 0
165 0.8 1 1
3.0 0 0
6.0 3 0
12.0 1 3
155 0.8 850 500
3.0 1,820 840
6.0 120 40
12.0 20 0
145 0.8 12,500 4,500
3.0 13,200 5,000
6.0 9,200 5,300
12.0 5,000 2,600


after extraction.
Florida Citrus


o Mixed culture added in active growth phase because of low count in juice
Citrus Station Mimeo Report 54 6. Florida Citrus Experiment Station and
Commission, Lake Alfred, Florida. 462d-10/6/53 RP






TABLE 6


Effect of heat treatment on


the destruction of microorganisms in Valencia orange juice
from grove-run fruit, pH 4.0 c


Exposure Numbers per ml of juice
Temp* time Dextrose tryptone Orange serum
F. Sec. agar, pH 7.0 agar, pH 5.6


None
190


Florida Citrus


None
0.8
3.0
6.0
12.0
0.8
3.0
6.0
12.0
0.8
3.0
6.0
12.0
0.8
3.0
6.0
12.0
0.8
3.0
6.0
12.0
0.8
3.0
6.0
12.0


185


175


100,000
91
77
78
110
111
68
88
76
135
113
147
114
125
225
155
85
570
1,380
720
770
6,900
3,700
3,700
3,800


165



155


80,000
47
40
32
67
85
36
68
60
82
45
70
61
126
122
138
80
400
1,080
430
250
1,000
2,000
700
600


145


c Only soft rotting fruit discarded.
Citrus Station Mimeo Report 54 6. Florida Citrus Experiment Station and
Commission, Lake Alfred, Florida. 462e-10/6/53 RP


-






TABLE 7
Effect of heat treatment on the destruction of microorganisms in two, three, and four-fold d
concentrates prepared from grove-run Pineapple oranges c


Te. Ex e D e Numbers per ml. of reconstituted juice .
Temp. Exposure -Dexrose trptone agar, pH 7.0 .... Orange serum agar, pH 5.6
oF. Se. Concentrates, pH 3.9 Concentrates, pH 3.9
Sec 2-fold 3-fold /-fold 2-fold 3-fold 4-fold

None None 100,000 120,000 200,000 90,000 100,000 180,000
185 3.0 200 80 30 0 0 40
6.0 250 80 30 0 0 0
12.0 250 90 50 0 0 0
175 3.0 400 60 10 0 0 0
6.0 230 70 10 0 0 0
12.0 250 100 10 20 0 0
165 3.0 220 70 40 120 10 20
6,0 320 0 30 0 0 7
12.0 310 60 20 10 0 0
155 3.0 1,250 1,090 1,850 1,250 660 870
6.0 900 500 320 250 530 200
12.0 850 200 120 0 260 75
145 3.0 6,300 5,500 4,700 6,700 38,400 3,900
6.0 4,500 28,230 6,300 4,000 50,000 4,750
12.0 2,500 6,660 5,860 0 6,330 3,350


d Based
e Mixed


on 12.5oBrix Juice,
culture added in active growth phase because of low count in juice after extraction.


Citrus Station Mimeo Report 54 6. Florida Citrus Experiment Station and Florida Citrus
Commission, Lake Alfred, Florida. 462f-10/6/53 RP






TABLE 8
Effect of heat treatment on the destruction of microorganisms in two, three, and four-fold
concentrates prepared from grove-run Valencia oranges g

Expsr ,Numbers per ml. of reconstituted juice
Temp. Exposure Dextrose tryptone agar, pH 7.0 Orange serum agar, pH 5.6
time
oF. Concentrates, pH 3.8 Concentrates, pH 3.8
Sec. 2-fold 3-fold 4-fold 2-fold 3-fold 4-fold

None None 375,000 266,600 200,000 200,000 100,000 200,000
185 3.0 140 50 80 35 0 20
6.0 75 60 140 10 0 30
12.0 75 60 Spreaders 10 0 20
175 3.0 80 50 50 25 60 90
6.0 100 120 Spreaders 35 10 30
12.0 90 60 110 .35 10 50
165 3.0 TNTC 10,500 80 31,500 210 9,800
6.0 7,000 430 150 2,800 2,660 1,170
12.0 150 80 110 .O 10 0 ...30
155 3.0 122,500 88,600 70,000 84,000 93,330 35,000
6.0 1,000 102,600 70,000 52,500 81,330 42,000
12.0 1,500 Spreaders 200 35,000 2,330 38,000
145 3.0 200,000 102,000 70,000 300,000 84,000 56,000
6.0 136,000 126,000 42,000 86,000 107,300 84,000
12.0 280,000 74,600 70,000 130,000 77,000 56,000

fBased on 12.5Brix juice.
g Mixed culture added in active growth phase because of low count in juice after extraction.
Citrus Station Mimeo Report 54 6. Florida Citrus Experiment Station and Florida Citrus
Commission, Lake Alfred, Florida. 462g-10/6/53 RP






TABLE 9
Effect of heat treatment on the destruction of microorganisms in two, three, and four-fold h
concentrates prepared from grove-run Valencia oranges 1


Numbers per mal of reconstituted juice
Temp. Exposure Dextrose tryptone agar, pH 7.0 Orange serum agar, pH 5.6
time .... .. ..
OF. e Concentrates, pH 3.9 Concentrates, pH 3.9
2S 2-fold 3-fold 4-fold foldold 3-fold -fold
None None 30,000 80,000 250,000 300,000 40,000 100,000
185 3.0 160 80 100 70 30 30
6.0 130 50 50 50 30 20
12.0 150 60 50 100 0 30
175 3.0 200 90 90 60 20 30
6.0 110 100 130 80 10 10
12.0 160 60 40 110 30 30
165 3.0 200 200 1,040 500 200 400
6.0 800 300 840 0 100 40
12.0 10 110 70 0 30 10
155 3.0 8,200 5,700 4,500 6,800 4,100 300
6.0 4,200 3,500 4,400 600 5,000 3,900
12.0 2,700 1,300 800 200 .300 ..600
145 3,0 43,000 7,900 30,000 40,000 20,000 2$5000
6.0 27,000 16,000 12,000 30,000 15,000 25,000
12.0 2,000 10,800 64,000 6,000 12,100 10,000

h Based on 12.5oBrix juice.


i Included rotting fruit and


damaged culls.


Citrus Station Mimeo Report 54 6. Florida Citrus Experiment Station and Florida Citrus
Commission, Lake Alfred, Florida. 462h-10/6/53 RP




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