Estimation of Albumin Denaturation Temperature in Hydrogenated Starch Hydrolysate Solutions Based on Water Activity Measurements

This study demonstrates correlations between water activity (a_w) and albumin denaturation temperature (ADT), and the density of intermolecular hydrogen bonding of free water (D_oh(w-s)) in hydrogenated starch hydrolysate (HSH) solutions. We first measured the osmotic concentration (c) of sugar solutions of known molecular weight (MW) and found a significant linear relationship between 1/c and MW (r²＝0.998, P＜0.0001). Next, D_oh(w-s) was calculated using the MW estimated from this relationship and the glass transition temperature, and the relationships between D_oh(w-s) and a_w, and between D_oh(w-s) and ADT were clarified. Linear regression analysis revealed a significant and positive linear relationship between D_oh(w-s) and a_w (r²＞0.900, P＜0.0001), and a significant and negative linear relationship between D_oh(w-s) and ADT (r²＞0.900, P＜0.0001). The findings also showed that the ADT of the HSH solutions could be estimated using a_w, which is easy to measure, and that the Spearman correlation between the measured and estimated ADT is significant (r²＝0.930, P＝0.00280). The results suggest that the ADT of HSH solutions can be estimated at any HSH concentration and any sugar composition by measuring the a_w values of the solutions.