Assessment of Physico-chemical Characteristics, Viability and Inhibitory Effect of Bifidobacteria in Soymilk

Abstract

The study investigated viability of Bifidobacteria isolates from breast-fed infants in soymilk with the aim of producing a beverage with health-improving potentials from an affordable source. Strains of Bifidobacteria spp isolated from breast-fed babies were identified on the basis of morphological and biochemical characteristics. The pure isolates were inoculated into sterile soymilk and their viability was studied at ambient (28 ± 2 o C) and refrigeration temperatures (4 ± 1 o C) The bifidobacteria isolates were identified as B. adolescentis and Bifidobacterium longum. The inhibitory effects of the Bifidobacteria isolates were tested on Escherichia coli and Staphylococcus aureus. B. longum was found to be viable for 35 days and inhibited Escherichia coli better than Staphylococcus aureus. Changes in the physico-chemical characteristics of the inoculated soymilk were also monitored over the storage period. Crude protein increased from 1.76 to 2.14% and 1.96% in soymilk samples stored at ambient and refrigeration temperatures respectively. The study has shown that B. longum which is supported by soymilk exhibits antimicrobial activity against tested food borne pathogens – indicating that probiotic soymilk could be produced from B. longum and soymilk.