O0102 PROTEIN HYDROLYSIS OF INFANT FORMULAS STRONGLY ACTIVATES THE MAILLARD REACTION

Abstract

Introduction: The particular composition of infant formulas favours the development of the Maillard reaction during processing, inducing nutritional and health hazard effects such as loss of available lysine and promotion of the inflammatory response. Lactose, the main substrate of the reaction in milk, is present at high concentrations. Ascorbate and polyunsaturated fatty acids are oxidable nutrients which give rise upon heat treatment to many other reactive dicarbonyle substrates. These substrates attack the free amino groups of proteins, mainly the e-NH2 group of lysine in milk proteins. Hydrolysis of the proteins induces a tremendous increase of the reactive amino groups, via the terminal a-NH2 of peptides or free amino-acids. The aim of this study is to evaluate the effect of protein hydrolysis on the Maillard reaction in the formula. Four indicators were selected to estimate the nutritional quality and safety of infant formulas. Methods: Hydrolyzed and non hydrolyzed formulas processed as powders or sterilized liquids were purchased from the market (Germany and France). Furosine and free hydroxymethylfurfural were quantified by HPLC-UV; carboxymethyllysine (CML) was estimated by ELISA and fluorescent Maillard products (FMP) were measured directly on the powders or liquid samples by front-face fluorescence. These indicators were also measured on samples stored at 60°C for 4–7 days, to mimic long storage. Results: Hydrolysis of the proteins strongly (2 to 3 times) increased the furosine and CML contents of the formulas. Similarly, FMP were significantly higher indicating that protein hydrolysis is an important parameter for the rate of development of the Maillard reaction. The type of process also had a significant effect, as powders were less altered than sterilized liquid formulas. However, accelerated aging had a much stronger effect on powders, especially when the water content was higher than 6 %. Conclusion: Protein hydrolysis is proposed to decrease the allergenicity to milk proteins. However, the liberation of free reactive amino-groups strongly increases the Maillard reaction with possible nutritional and safety consequences. Milder heat treatments for drying and sterilizing should limit the extent of the Mail-lard reaction.