Effect of Protectant Stability Properties on The Viability of Geotrichum candidum RO294 After Freeze-Drying

The protective effect of three disaccharides (Trehalose, Maltose and Sucrose), alone or in combination with skim milk, was studied during freeze-drying of Geotrichum candidum RO294. Two freeze-drying temperatures were investigated, 25 and 35oC. Glass transition temperature (Tg) of freeze-dried protectants was measured by differential scanning calorimetry (DSC). The results showed that concentration of the protectants is a major parameter to increase viability of G. candidum RO294 after freeze-drying. Addition of skim milk to the protectants increased, in general, the viability of freeze-dried G. candidum RO294. Trehalose alone proved to be the best protectant, followed by Maltose and Sucrose in decreasing order. Glass transition temperature determinations of these sugars confirmed that the best protectants have the highest Tg values.