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Kinetics of an Acid‐Base Catalyzed Reaction (Aspartame Degradation) as Affected by Polyol‐Induced Changes in Buffer pH and pK a Values
Author(s) -
Chuy S.,
Bell L.N.
Publication year - 2009
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2008.01015.x
Subject(s) - aspartame , chemistry , polyol , sucrose , buffer solution , dilution , phosphate , degradation (telecommunications) , phosphate buffered saline , hydrolysis , buffer (optical fiber) , citric acid , kinetics , glycerol , chromatography , organic chemistry , biochemistry , telecommunications , physics , quantum mechanics , computer science , polyurethane , thermodynamics
The kinetics of an acid‐base catalyzed reaction, aspartame degradation, were examined as affected by the changes in pH and pK a values caused by adding polyols (sucrose, glycerol) to phosphate buffer. Sucrose‐containing phosphate buffer solutions had a lower pH than that of phosphate buffer alone, which contributed, in part, to reduced aspartame reactivity. A kinetic model was introduced for aspartame degradation that encompassed pH and buffer salt concentrations, both of which change with a shift in the apparent pK a value. Aspartame degradation rate constants in sucrose‐containing solutions were successfully predicted using this model when corrections (that is, lower pH, lower apparent pK a value, buffer dilution from the polyol) were applied. The change in buffer properties (pH, pK a ) from adding sucrose to phosphate buffer does impact food chemical stability. These effects can be successfully incorporated into predictive kinetic models. Therefore, pH and pK a changes from adding polyols to buffer should be considered during food product development.