INITIAL LOSSES OF AVAILABLE LYSINE IN MODEL SYSTEMS

The initial loss rates of available lysine during thermal processing were studied to develop an equation for predicting the specific reaction rate (k_T). The reaction order for initial loss was first determined and then the effect of system composition on the specific reaction rate investigated. The ability of the model system in phase three (no further loss with heating) to revert to phase one (initial loss rate) after mixing was also examined. A model system, consisting of protein, glucose and microcrystalline cellulose was utilized. The system composition (pH, water activity and glucose level) and time and temperature of the processing were varied. The reaction resulting in the initial rapid phase (one) of available lysine loss occurs according to first order reaction kinetics. Glucose and temperature have the dominant effect on predicting k_T. Both pH and activity also influence the prediction of k_T but they act through an interaction with glucose. Once the soy based food system enters phase three, the system does not revert to phase one by the re‐slurry method. Sugar exhaustion does not account for the inability to revert to phase one.