The Relation between Acids and Pectin in Jelly Formation

Abstract

An "optimum acidity" range for fruit jelly-making by the hot method has been reported by different workers. Tarr1 has attached pectin-acid compound significance to this and supports his hypothesis by a series of experiments in which the number of cc. of different acids required to give a definite

Pectin Studies

“…The well-known data of Tarr (6) and Baker (1) suggest such a high degree of sensitivity of apple pectin towards moderate changes in acidity that the routine method proposed for citrus pectins cannot be expected to be applied without modifications in the evaluation of apple pectins. The data of these workers, in so far as they relate to the optimum pH of apple pectin jellies prepared by the usual "hot" method (5), are in essential agreement with unpublished data accumulated in the authors' laboratories over a period of years. in the same gelometer readings.…”

A Note concerning Ion Adsorption by Pectin.

“…In 1929 and 1930 Miss Spencer published a series of papers dealing with the influence of sugar, salts, and acids on pectin gels. The third paper (2) of that series was devoted to a critical discussion of the 1923 data of Tarr (3). Miss Spencer used the data of Tarr to substantiate her contention that pectin carries a negative charge in solution due to adsorbed anions and to show that pectin does not possess a "buffer action" in acid solutions, as was claimed earlier by Tarr. It has been felt in these laboratories that Miss Spencer erred mathematically in her interpretation of Tarr's data and that consequently her postulates were without suitable foundation.…”