Characterization and yeast cryoprotective performance for thermostable ice-structuring proteins from Chinese Privet (Ligustrum Vulgare) leaves

Thermal hysteresis activity (THA) of thermostable ice-structuring protein (TSISP) extract from Chinese Privet (Ligustrum vulgare) leaves was measured by differential scanning calorimetry (DSC) and the effects of the TSISPs on the physicochemical properties of yeast cells (intracellular ice formation (IIF), released glutathione (GSH) amount and survival ratio) and dough characteristics (breakdown of gluten proteins and fermentation capacity) during frozen storage were investigated by DSC, SDS-PAGE and Rheofermentometer. The THA ranged from 0.13 to 0.27 based on different ice fractions in solution. TSISPs added to a frozen yeast suspension caused a decrease in the IIF and released GSH amount of yeast cells, an increase in the survival ratio of yeast cells as well as a reduction of breakdown of gluten proteins in dough mixed with frozen yeast suspension. TSISPs improved the gas production and retention of frozen yeast suspension doughs. ► We extracted and partially characterized a TSISPs from Chinese Privet leaves. ► We studied effects of TSISPs on physicochemical properties of yeast cells and dough. ► TSISP decreased IIF and GSH amount of yeast cells and increased yeast survival ratio. ► TSISPs prevented breakdown of gluten proteins in frozen yeast suspension dough. ► TSISPs improved rheofermentation of frozen yeast suspensions doughs.