Research Information System
CRYOBIOLOGY, pp.122-129, 2020 (SCI-Expanded)
In this study, the response surface methodology was used to optimize the cryoprotective agent (skimmed milk powder, lactose and sucrose) formulation for enhancing the viability of Lactobacillus curvatus N19 during freeze-drying and storage stability of cells freeze-dried by using optimum formulation was evaluated. Our results showed that the most significant cryoprotective agent influencing the viability of L. curvatus N19 to freezing and freeze-drying was sucrose and skim milk, respectively. The optimal formulation of cryoprotective agents was 20 g/100 mL skim milk, 3.57 g/100 mL lactose and 10 g/100 mL sucrose. Using the optimum formulation during freeze-drying, the cell survival was found more than 98%. Under the optimal conditions, although only storage of the cells at 4 degrees C for 6 month retained the maximum stability (8.85 log cfu/g), the employed protectant matrix showed promising results at 25 degrees C (7.89 log cfu/g). The storage stability of cells under optimized conditions was predicted by accelerated storage test, which was demonstrated that the inactivation rate constant of the freeze-dried L. curvatus N19 powder was 9.74 x 10(-6) 1/d for 4.C and 2.08 x 10(-3) 1/d for 25 degrees C. The loss of specific acidification activity after the storage at 4 and 25 degrees C was determined.