CITRUS PECTIN • 7 
Table 7. — Results of two three-quarter-hour extractions of orange peel at 98° C, 
varying the acidity 
Extraction 
Acidity 
(citric 
acid) 
Pectin 
in peel 
Pectin lor 
a good 
jelly 
Lot 1 : 
First 1 
Per cent 
0.03 
.01 
.29 
.10 
Per cent 
0.43 
1.16 
.90 
1.60 
Per cent 
0.60 
Second 
2.20 
Lot 2: 
First. 
.31 
Second .._.._....... .. . 
.34 
The results up to this point indicated that an hour's heating of the 
peel at 98° C. in three times its weight of slightly acid solution (at 
least 0.1 per cent) yielded a fair quantity of good-quality pectin. 
vSamples 1 to 5, inclusive, of the pectins shown in Table 3 were of 
poor quality, because of the low acidity. There was no advantage in 
extracting the pectin above the simmering temperature of 98° C. The 
finer the peel, the more readily the pectin was removed. 
In order to determine the proper acidity and feasible number of 
extractions, 1,800 grams of finely ground lemon peel was divided into 
eight lots of 225 grams each and extracted twice for 45 minutes at 
98° C. Additional extractions were made on samples 3 and 6. All 
of these results are given in Table 8. 
Table 8. — Results of two three-quarter-hour extractions of lemon peel at 98° C, 
varying the acidity 
Sample 
No. 
Acidity 
(citric 
acid) 
Pectin 
in peel 
Pectin for 
a good 
jelly 
1 
2 
3 
4 
5 
6 
7 
8 
Per cent 
0.02 
.12 
f.21 
1.21 
.30 
.44 
f.64 
\.64 
.88 
1.20 
Per cent 
1.92 
.98 
1.22 
1.32 
1.46 
1.69 
2.26 
1.38 
2.18 
2.71 
Per cent 
1.33 
.25 
.25 
.60 
.25 
.25 
.25 
1.70 
.25 
.35 
Two 200-gram samples of one lot of lemon peel were heated three 
times at 98° C. with 0.4 per cent acid, one sample for 60 and the 
other for 90 minutes. The results are shown in Table 9. 
Table 9.- 
■Results of three extractions of lemon peel at 98 c 
citric acid 
C. with 0.4 per cent 
Sample 
No. 
Extraction 
Time of 
heating 
for each 
extraction 
Pectin 
in peel 
Pectin 
for a 
good 
jelly 
1 
Minutes 
60 
60 
90 
90 
Per cent 
2.52 
.83 
2.96 
.79 
Per cent 
0.25 
1 
Third — - 
.51 
2 
.34 
2 
Third 
.68 
