Moisture profiles analysis of food models undergoing glass transaction during air drying
Gulati, T., Datta, A. K. (2015). Mechanistic understanding of case-hardening and texture development during drying of food materials. Journal of Food Engineering 166, 119-138.
Plain language summary
The effect of glass transition on moisture profiles during air-drying of two gel food systems and potato at different drying conditions was analyzed in the present work. Thickness of the dry layer at the product surface was estimated from the MRI moisture profiles during drying. The moisture profiles of two maltodextrin-agar gel samples having different glass transition temperatures (MD19 MD36) and potato, dried at 25 and 55°C with air speed of 1.6m/s presented a square form at the beginning of drying process. After some time, their moisture profiles became round as predicted by Fick’s law. The moisture profile of MD19 and MD36 was found to be rounder than for potato because of a thicker dry layer formed at the surface of potato samples affecting the diffusion of water. A sharp diminution of moisture near the surface of the sample (dry layer) was observed, especially from the middle stages of drying. The formation of a dry layer at the surface of MD19 and MD36 gel systems dried at the same temperature was considered similar despite their different glass transition temperatures.