10 
BULLETIN 1323, IT. S. DEPARTMENT OF AGRICULTURE 
and combine with the paste to form a granular nongelatinous mass, 
from which the solvent could be removed by pressure before drying. 
A continuous system of washing and a constant temperature of about 
60° C. were advantageous for large quantities of the paste. The best 
temperature for concentrating the pectin solution was 60° C. Much 
higher temperatures impair the jellying power of the pectin and give 
a dark product. As a preliminary treatment the freshly ground resi- 
due or peel was soaked overnight in three of four times its weight of 
water, the excess of which was poured off. In this way much of the 
bitter matter and of the color, but only a trace of pectin, was removed. 
The results obtained by using 60 per cent ethyl alcohol in preparing 
pectin paste were compared with those obtained by using 60 per cent 
ethyl alcohol denatured with 5 per cent methyl alcohol, ethyl acetate, 
and benzol, respectively, in the following experiment: 
Four hundred cubic centimeters of pectin extract containing 0.02 
per cent acid, and therefore of low jellying power, was precipitated 
with 60 per cent alcohol, washed, and dried. Forty-five hundred 
cubic centimeters of the same extract was evaporated below 60° C. 
to 360 grams of paste, which was divided into four parts, placed in 
Erlenmeyer flasks, heated for an hour at 60° C. with 200 cc. of the 
mixtures listed in Table 12, and dried. 
Table 12. — Effect of denatured alcohol in preparation of -pectin 
Treatment 
Dried 
material 
Pectin 
Sample 
No. 
In dry 
material 
Calcu- 
lated 
to be in 
original 
extract 
Required 
for a 
good 
jelly 
1 
Precipitated with ethvl alcohol 
Grams 
2.21 
7.34 
7.47 
7.30 
7.22 
Per cent 
70.0 
57.0 
64.8 
66.3 
59.3 
Per cent 
0.39 
.37 
.43 
.43 
.38 
Per cent 
0.4 
2 
.5 
3 
4 
5 
Paste; ethyl alcohol and 5 per cent methyl alcohol 
Paste; ethyl alcohol and 5 per cent ethyl acetate 
.5 
.5 
.5 
As the quantity of pectin, calculated from the dry matter of the 
original extract, was within the experimental error for each of the 
alcoholic mixtures, the results show that the denatured alcohols are 
as suitable for purification as ethyl alcohol. The jellying power of 
the pectin in the paste was only slightly affected by the concentration 
and washing. 
Several lots of pectin were made by the following method: The 
pectin solution was concentrated to a thick paste (from 25 to 50 per 
cent solids) and washed with alcohol denatured with benzol. Al- 
though the facilities in the laboratory did not permit the production 
of pectin on a large scale, this method is here proposed for use on the 
commercial scale. The operation on one lot was as follows: Thirty 
liters of water was added to 8.6 kilograms of finely ground peel from 
slightly green lemons, and, after remaining on the peel overnight, 
was pressed out. The residue was heated twice for an nour at 98° C, 
with 25 liters of water containing 0.4 per cent of citric acid. The 47 
liters of extract obtained was filtered, using 2 per cent of kieselguhr, 
