Kinetics ascorbic acid destruction

Kinetics of Ascorbic Acid Destruction During Processing and Storage... 

To predict nutrient deterioration, knowledge of the reaction rate as a function of temperature of storage or processing is needed. The kinetics of ascorbic acid destruction have been examined most extensively in model systems, with particular attention being given to intermediate moisture foods (17, 71,78,79). Most of the data available for vitamin C losses in actual food systems are insuflBcient to calculate the kinetic parameters needed to predict losses during heat treatment or storage. 

According to Lenz and Lund (72), kinetic models for destruction of food components are needed to improve products by minimizing quality changes for new product development and to predict shelf life during storage. Numerous reports and reviews of the kinetics of ascorbic acid destruction can be found in the literature (68-88). A brief overview is presented here to indicate the need for further research in this area. 

If the destruction of a component is presumed to be zero-order, a plot of C vs. t should give a straight line. Certain losses of vitamin C, particularly in frozen foods, are presumed to follow first-order kinetics (89). Labuza (76) observed that zero-order reaction rates for quahty losses may be assumed in some fluctuating temperature studies, but this may lead to a miscalculation of predicted changes. Therefore, from a theoretical standpoint, it is important that the proper order be used for predictions. In general, ascorbic acid destruction is assumed to be first-order, or pseudo first-order (17,27) except under specific conditions of heat and moisture (79). 

Mechanism of Reaction Proposed in Relation to Water and Kinetics of L-(+)-ascorbic Acid Destruction... 

The present chapter deals with the study of edible films based on deacylated and/or acylated forms of gellan gum to support L-(+)-ascorbic acid (AA) in view of natural antioxidant protection of foods, by leveraging its activity as a vitamin in the human metabolism. Kinetics of AA-destruction and subsequent non enzymatic browning development were studied in the films stored at constant temperature (25 C) and relative humidity (33.3, 57.7 or 75.2%) and their relationship with the microstructure, at the macromolecular and molecular levels, was also analyzed with the purpose of ensuring a better AA retention as well as lower browning rate as a consequence of controlled water mobility in the polymeric networks. 

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