Citrus Station Mimeo Report 59-2
October 2, 1958

The Problem of Recovering Fruit Solids from Orange Pulp

R. L. Huggart, R. W. Olsen and F. W. Wenzel



During the 1957-58 citrus season, many processors became keenly interested
in the problem of recovering fruit solids from orange pulp. Using various pro-
cedures, soluble solids in orange pulp may be almost completely removed by
water extraction and the use of such solids in the production of frozen orange
concentrate makes possible an increase in yield of concentrate per box of fruit.
Such an increase in yield is always desirable for economic reasons, provided
that such an increase does not harm the quality of the concentrate. Because of
many questions that have been raised concerning this problem, some investigations
were made during the past season in an attempt to obtain some factual information
on this subject.

Data presented in Tables 1 to 4 were obtained from the examination of both
experimental and commercial water extracts of orange pulp and show the range
of values that were found for various characteristics of these products.

Information in Tables 5 to 7 pertain to procedures that may be involved
in recovering soluble solids from orange pulp by extraction with water.

On the basis of the data obtained to date, investigation of this problem
will be continued during the coming season.





















Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
876f 10/2/58 RLH







Table 1. Characteristics of experimental and commercial water extracts of orange pulp
,rix Aci as Br,/cip


Description
of sample


Brix Acid as Brix/acid pH
value citric-% ratio
Experimental samples


Relative
viscosity1


Light
transmittance


1st extraction
2nd extraction
1st extraction
2nd extraction
Extract of rag and seeds

Hot extraction
Cold extraction

Juice from 2nd finish
1st extraction
2nd extraction


Concentrated extract

Concentrated extract
n it



in orange juice 3


4.5
2.0
3.8
1.5
3.1

3.2
3.0
10.5
5.0
2.5


41.8
9.3
42.0
42.0
7.0
8.0
5.5
11.8-
12.0


0.27
0.11
0.11
0.04
0.05

0.13
0.13

0.50
0.22
0.11


16.7
18.2
34.5
37.5
62.0

24.6
23.1
21.0
22.7
22.7


Commercial samples


2.41
0.48
2.44
2.39
0.37
0.40
0.27
0.80-
0.98


17.3
19.4
17.2
17.6
18.9
20.0
20.4
13-
16


1 Data obtained from G. H. Ezell.
3 Range of values in reconstituted juices fr
frozen orange concentrate collected from F:

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
876 a 10/2/58 RLH


2 Apparent viscosities in centipoises
,m 70% or more of the 212 samples of commercial
Lorida plants during the 1956-57 season.


Sample
number


11
12
13
14
15
16
17
Range


4.0
4.2
4.6
4.9
5.2

4.4
4.4
4.2
4.3
4.4


3.8
4.0
3.8
3.8
4.1
4.1
4.2
3.5-
3.7


1.15
1.04
1.23
1.14
3.59

1.60
1.27
1.29
1.25
1.29


2200 2
1.71
8802
602
1.86
2.43
1.39








Table 2. Sugar content of experimental and commercial water extracts of orange pulp


Sugars1


Sample Reducing
number g./100 ml.


Sucrose
g./100 ml.


g./100 ml.


Total
g./100g.2


Brix
value3


% of Brix value
equivalent
to sugars


Experimental samples
3.53 3.48
1.33 1.33


2.79
1.05
1.96

2.25
2.25

8.09
3.50
1.72


2.75
1.04
1.94

2.22
2.23

7.75
3.44
1.71


2.24
1.20

2.03
1.05
1.84

1.26
1.24

3.21
1.94
1.13


20.72
3.48
18.80
19.84
2.89
3.56
2.58


39.56
7.56
39.00
39.86
5.28
6.25
4.59


33.3
7.30
32.8
33.6
5.14
6.05
4.49


Samples analyzed by S.
263-266 (1956). Rapid
sugars and fructose in


V. Ting. Method published in Agricultural and Food
colorimetric methods for simultaneous determination
citrus juices.


Chemistry, A,
of total reducing


2 Calculated
3 Brix by refractometer and not corrected for acid.
Florida Citrus Experiment Station
and Florida Citrus Commission
Lake Alfred, Florida. 876 10/2/58 RLH


1.29
0.13
0.76
0.00
0.12

0.99
1.01

4.88
1.56
0.59


Commercial samples


4.5
2.0

3.8
1.5
3.1

3.2
3.0

10.5
5.0
2.5


41.8
9.3
42.0
42.0
7.0
8.0
5.5


18.84
4.08
20.20
20.04
2.39
2.69
2.01





Table 3. Pectic substances in experimental and
commercial water extracts of orange pulpl
Pectin2 as anhydrogalacturonic acid-mg./lOO g.
Sample Ammonium Sodium
number Water oxalate hydroxide Total


Experimental samples


18.3
25.3

40.9
27.8
268.0

97.9
64.0

34.1
68.6
83.1


36.8
44.2

55.4
60.0
101.2

41.4
42.8

141.4
43.3
67.8


27.3
31.6

34.8
45.0
88.0

59.2
58.8

133.2
42.4
107.5


82.4
101.1

131.1
132.8
457.2

198.5
165.6

308.7
154.3
258.4


Commercial samples


11 68.4
12 147.8
13 40.0
14 38.0
15 91.4
16 170.0
17 79.9
Range in
orange juice3 35-49


1 Samples analyzed by A. H. Rouse, C. D.
E. L. Moore.


Atkins and


For comparison purposes, all values are given on a
120 Brix basis.
3
See footnote on Table 1.
Florida Citrus Experiment Station and Florida Citrus Commission,
Lake Alfred,, Florida. 876 b 10/2/58 RLH


3.8
56.5
23.3
2.7
94.8
82.1
79.9


2.1
44.3
34.7
1.7
85.7
85.1
61.5


74.3
248.6
98.0
42.4
271.9
337.2
221.3





Table 4. Characteristics of experimental and commercial water extracts of orange pulpl


Pectinesterase
activity2'3


Water-insoluble Pulp3
solids3
mg./100 g. % by vol.
Experimental samples


Flavonoids
as hesperidin3
mg./100 ml.


Ascorbic
acid
mg./100 ml.


11
12
13
14
15
16
17
Range in
orange juice4


97.1
65.7

131,7
108.0
435.2

185.8
176.0

596.0
156.7
284.3


58.5
79.3

46.6
89.2
66.5

6.5
28.7

97.3
32.2
61.5


0.3
43.9
2.6
0.1
68.1
80.3
54.0
1.3-
6_9


8.2
10.1

13.5
31.5
42.4

11.6
33.6

46.6
34.3
36.9


Commercial samples


48.4
241.6
394.0
22.8
321.6
419.4
267.4
100-
199


3.5
44.1
12.4
0.8
41.7
42.2
35.4
7-
11


1 For comparison purposes, all values are given on a 120 Brix basis.
2 (PE.u.)g. soluble solids X 1000.
3 Data obtained by A. H. Rouse, C. D. Atkins and E. L. Moore.
See footnote 3 on Table 1

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida 876 c 10/2/58 RLH


Sample
number
i i


133.1
154.1

180.9
201.7
495.6

188.9
167.6

246.6
168.5
206.3

128.0
215.1
100.0
97.5
233.5
225.9
220.9
70-
90


35
38
37
36
37
38
35
39-
56


6. 9







Table 5. Effect of pulp-to-water ratio for single extraction on the recovery of soluble
solids from orange pulp
Pulp Water Pulp/water Extract from finisher Soluble solids


ratio


grams grams


200
400
600
800
1000
1200
1400
2000


10.0
5.0
3.3
2.5
2.0
1.6
1.4
1.0


volume weight Brix soluble solids recovered1
milliliters grams grams %


690
870
1100
1250
1460
1650
1820
2400


715
899
1134
1286
1498
1689
1863
2447


9.0
8.5
7.9
7.3
6.6
6.1
6.0
5.0


64
76
"90
94
98
103
112
122


S216 grams of soluble solids calculated to be in the 2000 grams of wet pulp which had a Brix
value of 10.80. 64 grams of soluble solids recovered in the 690 milliliters or 715 grams of
water extract which had a Brix value of 9.00. Soluble solids recovered = 64 g./216 g. x 100 = 30%.


Table 6. Approximate number of gallons of water extract of orange pulp required to make
one gallon of 120, 420 or 550 Brix products

Brix
value
after Brix value in water extract
concentration 2 3 4 5 6 7 8 9 10 11 12
120 6.23 4.14 3.10 2.47 2.05 1.75 1.52 1.35 1.21 1.10 1.00
420 24.74 16.43 12.30 9.80 8.13 6.94 6.05 5.36 4.80 4.35 3.97
550 3433 22.79 17.06 13.60 11.28 9.63 8.39 7.43 6.66 6.03 5.51
1 Based on sucrose.values. See Moore, Edwin L. Fruit Products Journal and American Food
__Manufacturer 2, '11) 330-5, 349 (1949).
Floride'. Citrus FXpewrJmer-t S:'tion
and IF.o- C.itrus Corbmiision,
Lake Alfred, Florida. 876 d 10/2/58 RLH


2000
2000
2000
2000
2000
2000
2000
2000










Table 7. Comparison of double juice finishing with a combination of single
juice finishing and water extraction
i i t. . .. .. .. .


Volume Soluble
Brix 120 Brix solids
gal. lb.


Soluble solids
recovered
%o


Pulpy juice from extractor2

Juice from lst finisher
Juice from 2nd finisher
Pulp from 2nd finisher
Loss


Double finisher
64.8 10.5 56.42


56.6
2.4
5.2


10.6
10.2
10.0
- -,,


49.75
2.04
4.37
0.26


Single finisher and water extraction


Pulpy juice from extractor2

Juice from finisher
1st water extraction
2nd water extraction
3rd water extraction
Pulp removed from extracts
Loss


64.8 10.5 56.42


56.6
10.2
6.9
5.2
39.9


10.6
4.7
2.3
1.3
lb. 1.8


49.75
3.86
1.28
0.05
0.07
1.41


1 Calculated


Valencia oranges extracted using FMC Inline extractor with beam
and equipped with .09 finisher tubes and 7/16 inch restrictors.
of 10 boxes or 900 lb. of fruit.


setting flush
Data on basis


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
876 e 10/2/58 RLH


Products


Volume
gal.


59.08


52.08
2.14
4.58
0.28
Total


88.1
3.6
7.8
0.5
100.0


59.08

52.08
4.04
1.34
0.06
0.07
1.49
Total


88.1
6.8
2.3
0.1
0.1
2.6
100.0