Maillard reaction and lipid peroxidation contribute to non‐enzymatic browning in krill‐based products: A model study on proposed mechanisms

Abstract

The main objective of this study was to further investigate whether the occurrence of Strecker degradation in krill‐based products is due to the presence of N‐Acetylglucosamine (amino sugar derived from krill exoskeleton) or lipid‐derived carbonyls. A simple model system comprising amino acids was incubated at 60°C for 0, 3, 9, and 24 h with five selected lipid‐derived carbonyls or five Strecker‐derived volatiles or an amino sugar. The presence of both amino sugar and lipid‐derived carbonyls (especially α,β‐unsaturated aldehydes) caused non‐enzymatic browning reactions: (i) pyrrole formation; (ii) browning development; and (iii) Strecker degradation of amino acids, with a faster reaction rate by amino sugar. In addition, the presence of a high level of Strecker degradation products might enhance pyrrole formation.Practical applications: This work provides information about the Strecker degradation of amino acids induced by amino sugar (N‐Acetylglucosamine) and lipid‐derived carbonyl compounds, and the increase of pyrrole formation is ascribed to the presence of a high level of Strecker degradation products. The obtained knowledge from this fundamental study explains the occurrence of Strecker degradation in krill products especially after enzymatic treatment due to the increased level of amino acids, lipid oxidation products and amino sugar derived from krill shell. This information is not only applicable to krill matrix but also to similar matrices from other food systems.Non‐enzymatic browning reactions, especially Strecker degradation of amino acids in krill‐based products during their thermal treatment, are induced either through Maillard reaction due to the presence of amino sugar derived from krill exoskeleton or through the lipid peroxidation pathway due to the presence of unsaturated aldehydes derived from lipid oxidation.