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Reaction of apple pectin with ammonia
Author(s) -
KRATCHANOV Chr.,
DENEV P.,
KRATCHANOVA M.
Publication year - 1989
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1111/j.1365-2621.1989.tb00643.x
Subject(s) - chemistry , hydrolysis , ammonia , alcohol , pectin , aqueous solution , amide , organic chemistry , biochemistry
Summary Amidated apple pectins were prepared in aqueous and aqueous‐alcoholic media, and the factors influencing both ammonolysis and hydrolysis of the ester groups of apple pectin by ammonia were studied. In aqueous solution, the extent of ammonolysis and hydrolysis was very dependent upon ammonia concentration. In aqueous alcohol, the products were also dependent upon the particular alcohol and its concentration, increasing concentrations suppressing hydrolysis; the overall rate of reaction is much slower than in the absence of alcohol. The product balance between amonolysis and hydrolysis of the ester groups is influenced by the polarity of the medium, and by the concentration of NH + 4 and OH − . It was shown that the extents of ammonolysis and hydrolysis of the ester groups are significantly affected by the polarity of the medium and the acid‐base equilibrium of the interaction of ammonia with water, i.e. NH 3 +H 2 O ↔ NH + 4 +OH − . The content of free ester and amidated carboxyl groups in the pectin can be regulated by varying the concentration of ammonia, temperature, reaction time and the polarity of the medium. The rate of enzymic hydrolysis of amidated pectins decreases with increasing amide content. A mechanism for the reaction is proposed.