Effect of water content, temperature and storage on the glass transition, moisture sorption characteristics and stickiness of β‐casein¹

Published as paper number 99‐1‐18‐0017 of the contribution series of the Minnesota Agricultural Experiment Station based on research conducted under project 18‐24 and supported by the National Dairy and Promotion Board and the USDA National Needs Fellowship Program.

Abstract

Moisture sorption isotherms at +4 °C and +22.5 °C were obtained for β‐casein after isolation and after 9 months of storage at ‐29 °C and +22.5 °C. Glass transition state diagrams (T_g vs. moisture) were determined for β‐casein after storage. The results showed that effects of storage temperature on moisture sorption isotherms were varied; however, at any a_w differences in moisture content were small (< 0.03g H₂O/g solids at high a_w). β‐casein stored at ‐29°C had lower m_o and T_g values than that of β‐casein stored at +22.5°C. The glass transition temperatures for β‐casein were above room temperature, even at a_w = 0.76. Onset of stickiness occurred above a_w = 0.76.

Notes

Published as paper number 99‐1‐18‐0017 of the contribution series of the Minnesota Agricultural Experiment Station based on research conducted under project 18‐24 and supported by the National Dairy and Promotion Board and the USDA National Needs Fellowship Program.