16 BULLETIN 1323, U. S. DEPARTMENT OF AGRICULTURE 
SUMMARY 
The properties of citrus pectin and methods for its production 
were studied. 
The dialysis of pectin extracts in an osniogene containing collo- 
dion-impregnated cloth membranes removed most of the bitter prin- 
ciples, but the dialysis was too slow and about one-third of the 
pectin dialyzed. 
The best method of extraction was to heat the finely ground peel 
or residue with acidified water and clarify the expressed extract with 
kieselguhr. 
The bitter principle was removed with alcohol from powdered 
pectin prepared from concentrated solutions of pectin in the laboratory 
and in a commercial plant. 
A process whereby the pectin extracts are concentrated to a paste 
and washed by a continuous system with a minimum quantity of 
denatured alcohol was devised. 
Little hope is indicated of distinguishing chemically between 
lemon, orange, and apple pectins; the composition, when calculated 
to the alcohol-precipitate basis, is much the same for each product. 
A standard jelly test for determining the quality of the pectins 
produced throughout the investigation was developed. 
The proportions of citric acid, sugar, and citrus pectin required 
to give good jellies were determined. The lower limit in the finished 
jelly for citric acid was 0.045 per cent, for pectin 0.20 per cent, and 
for sucrose 37 per cent. 
BIBLIOGRAPHY 
(1) Abderhalden, Emil. 
Biocheniisches Handlexikon 2: 80-94. Berlin (1911). 
(2) Association of Official Agricultural Chemists. 
Official and tentative methods 1920, p. 156. Washington (1921). 
(3) Barker, B. T. P. 
Cider apple jelly. In Jour. Soc. Chem. Ind., T. (1918) 37: 243-246. 
(4) Beilstein, F. K. 
Handbuch Organischen Chemie (Aufl. 3) 1: 1104-1106. Hamburg 
and Leipzig (1893). 
(5) Bigelow, W. D., Gore, H. C, and Howard, B. J. 
Studies on apples. U. S. Dept. Agr., Bur. Chem. Bull. 94 (1905). 
100 pp. 
(6) Braconnot, Henri. 
Recherches sur un nouvel acide universellement repandu dans tous les 
vegetaux. In Ann. chim. phys. (1825) 28 (ser. 2): 173-178. 
(7) British Patents. 
11,823 (1914). Improved process for separating from a mixture one 
or more suspension colloids, emulsion colloids, true colloids, ions 
or dissolved bodies or members of two or more of these bases. 
21,448 (1914). Process for purifying and separating the constituents 
of glue, gelatine, or bodies like glue or containing glue, with aid of 
the electric current. 
188,387 (1922). Improvements in the production of a jelly base 
containing pectin. 
(8) Browne, C. A. 
A handbook of sugar analysis, p. 665. London (1912). 
(9) Caldwell, J. S. 
A new method for the preparation of pectin. Wash. Agr. Exp. Sta. 
Bull. 147 (1917). 14 pp. 
(10) Campbell, C. H. 
Jelly. In Ind. Eng. Chem. (1920) 12: 558-559. 
(11) — Scientific and practical manufacture of apple poniace jelly. In 
Canner (Nov. 10, 1923) 57 (no. 20): 23-25, 
