Standardization of lyophilization medium for Streptococcus thermophilus subjected to viability escalation on freeze drying

Rohit Sharma,Prakash S Bisen,Gulab S Thakur,Anjana Sharma,Bhagwan S Sanodiya,Pallavi Jaiswal

doi:10.4081/mr.2014.5402

Abstract

The objective of the present study is to develop a lyophilization medium for Streptococcus thermophilus (NCIM 2904) as the industrial exploitation of this bacterium totally depends upon preservation and lyophilization protocols. Protective effect of 18 compounds were observed individually and in combinations with different sugars, sugar alcohols, polymers, protein concentrates and buffers. Among all the protectants tested, ammonium citrate (1% w/w), K2HPO4 (1% w/w) and KH2PO4 (1% w/w) provided lowest protection to these bacterial cells while 10% (w/w) sodium caseinate, whey protein concentrate, sweet whey powder, and skim milk showed significant results in viability escalation. Survival in carbon sources like lactose, sucrose and maltodextrine was also favored maximally. Combination of sodium caseinate 10%, skim milk 5%, sucrose 5%, lactose 5% and mono sodium glutamate 1% in distilled water in ratio of 1:5 with S. thermophilus showed survival percentage of 96%.

Highlights

(w/w) sodium caseinate, whey protein concenm trate, sweet whey powder, and skim milk m showed significant results in viability escalation
In freezing stage the cells undergo through cold shock which may change the physical state of the membrane lipids undergoing a phase of transition which may odedwise rupture the cell wall. These negative effects are commonly protected by addition of some protective agents with the bacteria prior to lyophilization
Lactic acid bacteria are commonly used as starters for food fermentation with

Summary

Lyophilization medium

The following compounds were used to check the viability improvement. Sugars: Lactose, monohydrate (min 99.5%, milk sugar, Himedia, India), Sucrose, Extra pure (min 99.5%, Himedia, India), D-(-)Fructose, Extra pure (min 99%, Himedia, be tested on the basis of escalation in via- India), D-(+)-Glucose monohydrate 99.5%, Himedia, India), D-(-)-Mannitol, Extra pure (min 99%, Himedia, India), D-(-)-Sorbitol

Introduction

Proportion of addition*

Storage viability results

Conclusions

Findings

Future prospects