Maillard crosslinking of food proteins I: the reaction of glutaraldehyde, formaldehyde and glyceraldehyde with ribonuclease

The Maillard reaction influences not only the colour and flavour of foods, but also their texture, via protein crosslinking. In this, the first of a series of three papers to assess the potential of the Maillard reaction to alter food properties in situ, the capacities of three molecules—formaldehyde, glyceraldehyde and glutaraldehyde—to crosslink a model protein—RNAse—were compared. All three molecules crosslinked RNAse in vitro, with glutaraldehyde reacting at a much greater rate than either glyceraldehyde or formaldehyde, whose rates were comparable. Crosslinking correlated well with loss of lysine in the proteins for glutaraldehyde and glyceraldehyde, with some anomalies for formaldehyde. The differences in reactivity are explained by the proposed mechanisms of crosslinking for each of the three molecules. An understanding of the range of reactivity of crosslinking molecules, and how this relates to their molecular structure, may help us understand how to harness the Maillard reaction during food processing.