Glutathione, cysteine and mercaptans thiols interaction with antimicrobial activity of sorbic acid used in food and pharmaceutical products

ABSTRACT

Sorbic acid is used in various food and pharmaceutical products as antimicrobial additive to enhance their storage stability. However, the structure of sorbic acid is susceptible to interaction with electrophilic [amines] and nucleophiIic [thiols] ions of protein, amino acids and other thiols present in Food. The intcractions may reduce the sorbic acid function as a chemical preservative and the nutritional value of the proteins. Experiments of the reaction were conducted in model systern between sorbic acid and thiols additives such as glutathione [peptide], cysteine [amino acid], and simple mercaptans of mercaptoethanol and mercaptoacetic acid at temperature 30-80°C and ph 5.0 [acetate buffer 0.2 M]. Initial rates of the reaction were determined and were Found in second order. Activation energy of the reaction were obtained by plotting in [initial mute] vs I/T. Straight line graphs indicated that the results are consistent with the Arrhenius relationship and the slope of the line is Ea/R. The pre-exponentiaI factor was found from the intercept and the values of activation energy [Ea] of the reaction were 49.13, 46.55, 57 and 45.55 kJ mol[-1] for glutathione, cysteine, rnercaptoethanol and mercaptoacetic acid respeclively. From the results. It was found that sorbic acid stability as antimicrobial additive is decreasing in the presence of thiols of proteins, amino acids and simple mercaptans and the rates of reaction are increasing with increasing temperature