Modeling of the in vitro melanoid formation reaction on the interaction of protein hydrolysate of chicken egg and glucose

Abstract

Food production technologies, including heat treatment, are often accompanied by a change in their organoleptic characteristics (color, taste and aroma) due to the formation of colored substances as a result of the melanoidin reaction. The authors simulated the reaction of melanoidin formation in vitro using the example of the interaction of the hydrolyzate of a chicken egg protein and glucose to determine the content of amino acids depending on the conditions for carrying out this reaction. The egg protein (0.2 g) was subjected to acid hydrolysis for 24 hours at 80 °C. Then the hydrolyzate was neutralized (vend=100 см3) and the initial amino acid content was determined therein. In each sample (30 см3), 4.5 g of glucose was added to the hydrolyzate to obtain a 15% solution of glucose in the hydrolyzate. The effect of temperature (50, 70 and 90 °C), time (10, 30 and 50 min), pH (pH 2, 7 and 12) on the amino acid content in the hydrolyzate as a result of the melanoidin reaction has been studied. The determination of the amount of amino acids was carried out using high performance liquid chromatography with precolumnar derivatization using o-phthalaldehyde. As a result of the studies on modeling the melanoidin reaction, the following regularities were revealed: when the temperature of the Mayyar reaction increased, the concentrations of GLU, SER, HIS, THR, ARG, ALA, CYS, VAL, MET, LEU, and LYS decreased. At the same time, with an increase in the duration of the reaction, an increase in the concentration of SER, THR, VAL, MET, ILE, LEU was observed. Variations in the concentration of amino acids in the reaction medium with increasing temperature were characteristic for ASP, GLY, TYR, PHE, ILE, and with increasing the reaction time for ASP, GLU, HIS, GLY, ARG, ALA, TYR, CYS, PHE, LYS. Other things being equal, the process of melanoid formation most fully proceeded in an alkaline medium at pH 12. Thus, the study of the effect of the experimental conditions showed that during the melanoidin formation, the content of certain amino acids (including essential amino acids) decreases and, consequently, the nutritional value of the product decreases. As a result of this reaction, from 20 to 50% of free amino acids are lost, and with increasing temperature and increasing the duration of heating, these losses increase. The obtained data are important to take into account when developing new food technologies with the maximum preservation of their chemical composition, nutritional value and consumer properties.