Extension of shelf life of curd – an indian fermented milk by using a new isolate of Brevibacillus brevis strain as starter culture

Abstract

Brevibacillus brevis MMB 12 a new isolated bacteria from curd, was found to set curd within 5 hours of incubation at temperature of 42⁰C and showed a good shelf life, with thick invertible consistency up to 192 hours (8 days) of fermentation at ambient conditions. Curd was prepared by inoculating Brevibacillus brevis MMB 12 strain at 5% level and incubated at temperature of 42⁰C for 5 hours. The prepared curd was kept at ambient conditions which ranged from 16…24⁰C throughout the period of experimentation i.e. 8 days. Microbial count ranged between 3.50 ·10¹⁰ CFU/ml to 2.9·10⁹ CFU/ml and the acidity increased from 0.58 to 0.66 % during storage. Curd controled fermentation with a selected strain Brevibacillus brevis MMB 12 depicted low acidity compared to the curd inoculated with Lactobacillus delbrueckii subsp. bulgaricus which was taken as control sample. Mixed curd produced using Brevibacillus brevis MMB 12 and Lb. delbrueckii subsp. bulgaricus curd in 1:1 ratio (v/v) had a shelf life of 72 hours. Flavour, colour, cutting quality and acidity (sourness) were assessed for sensory qualities by 6 specialised trained panelists. Sensory attributes like cutting quality and taste of Brevibacillus brevis MMB 12 inoculated curd was rated higher than the other curds. Whereas for colour and flavour the control sample was rated better than Brevibacillus brevis MMB 12 inoculated curd.