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

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 (Tg 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 aw differences in moisture content were small (< 0.03g H2O/g solids at high aw). β‐casein stored at ‐29°C had lower mo and Tg values than that of β‐casein stored at +22.5°C. The glass transition temperatures for β‐casein were above room temperature, even at aw = 0.76. Onset of stickiness occurred above aw = 0.76.