Studies on the effect of protectants on Lactobacillus acidophilus strain dehydrated under controlled low‐temperature vacuum dehydration and freeze‐drying by using response surface methodology

Abstract

AbstractCa2+ (0–60 g litre−1), glycerol (0–100 g litre−1), and non‐fat dry milk solids (NFDMS, 0–140 g litre−1) were combined to study their effects on the survival of Lactobacillus acidophilus in controlled low‐temperature vacuum dehydration and freeze‐drying. A three‐variable (each at three‐levels) design method was used and analysed by fitting a quadratic response surface. These factors were found to be significantly effective on survival. Fitted quadratic regression equations were plotted using a graphing software package. Conditions for the best survival of freeze‐drying was found to be Ca2+ 5.34 g litre−1. NFDMS 100.8 g litre−1, and glycerol 41.5 g litre−1 and that of controlled low‐temperature vacuum dehydration was Ca2+ 5.67 g litre−1, NFDMS 107.1 g litre−1, and glycerol 41.0 g litre−1. Models obtained were tested using t‐tests. Survival of freezing under different conditions was found to be not significantly different.