The Contribution of Water to the Specific Heat Change at the Glass-to-Rubber Transition of the Ternary System BSA-Water-NaCl

• Published in: Journal of food science Vol. 65; no. 7; pp. 1187 - 1193
• Main Authors: Inoue, C., Ishikawa, M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2000; Institute of Food Technologists; Wiley Subscription Services, Inc
• Subjects: Animal, plant, fungal and microbial proteins, edible seaweeds and food yeasts; Biological and medical sciences; bovine serum albumin; Food engineering; Food industries; Frozen foods; Fundamental and applied biological sciences. Psychology; General aspects; Glass & glassware industry; glass transition; NaCl; specific heat change; unfrozen water; Water; Water; Glass transition; Specific heat; Ternary system; Foodstuff; Serum albumin; Serum protein; Sodium chloride; Physicochemical properties; Freezing; Property formulation relationship
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/j.1365-2621.2000.tb10263.x

We studied the glass‐to‐rubber transition of a BSA‐water‐NaCl system using DSC. The Tg was 178–187 K and decreased with increasing NaCl content from 1:9 to 6:4 NaCl:BSA. The specific heat change (ΔCp*, J/((g BSA)K)) at Tg increased as the weight ratio increased from 1:9 to 5:5 NaCl:BSA, as did the change in calculated unfrozen water (UFW). The UFW was also correlated with the amount of NaCl in the glassy region with a correlation coefficient of approx. 6 (mol H2O)/ (mol NaCl), which is comparable to the hydration number of Na+. These results suggest that UFW could contribute to the ΔC at Tg of the BSA‐water system.