Glass transition and state diagram for freeze-dried Lentinus edodes mushroom

Abstract

Glass transitions of freeze-dried Lentinus edodes mushroom were determined using differential scanning calorimetry (DSC) as a function of water contents. Freeze-dried L. edodes containing unfreezable and freezable water were examined to explore the state diagram of L. edodes. The state diagram included the freezing curve, glass transition line, and ultimate maximal-freeze-concentration condition. The freezing curve and the glass transition line were fitted according to Clausius-Clapeyron model and Gordon-Taylor model, respectively. The ultimate maximal-freeze-concentration conditions were calculated as solid content of 0.81g solid/g (w.b.) with the characteristic glass transition temperature (Tg′) being −53.2°C, and characteristic temperature of end point of freezing (Tm′)u being −33.4°C. The other characteristic glass transition temperature Tg″ was −42.4°C. The state diagram of Lentinus edodes can be used in determining the storage stability as a function of temperature and water content, and optimizing drying and freezing processes.