Shelf Life Profile Of Soymilk Beverage Using Starter Culture (lactobacillus Bulgaricus And Streptococcus Thermophilus).

Fermented foods are those processed through the activities of microorganisms. Soy milk is an aqueous extract from soybeans known for its nutritive health benefits. The aim of this work is to ferment soy milk product with starter culture (lactobacillus bulgaricus and streptococcus thermophilus) to prolong its shelf life. The soy bean was purchased from Ogbete main market located at Enugu North in Enugu state. It was immediately transferred to Godfrey Okoye University microbiology laboratory, where it was processed into soymilk. The processed product was pasteurized for 30mins, allowed to cool and added either milk or sugar as a carbon source before fermenting anaerobically with the starter culture (lactobacillus bulgaricus and streptococcus thermophilus) gotten from Aqua Rapha Company, Ninth mile, Enugu.

Temperature and pH variations of fermented soymilk samples (soymilk with both organisms, mixed with milk and sugar respectively, soymilk with both organism mixed with either milk or sugar respectively) were determined. Sample containing both organisms with milk and sugar respectively, have the highest temperature (80c) on day one and were slightly acidic (4.30), while sample containing both organism and sugar has the highest temperature (60c) on the last day and are slightly acidic (4.25). Proximate analysis of this various soymilk samples were determined. Sample containing both organisms and sugar has the highest protein content (3.678%) while the control shows the least value (0.347%).

Sensory evaluation showed that the product fermented with both organisms with milk and sugar was more acceptable than all other samples. Shelf life of these products were determined for 6 days. All the samples were acceptable from 0-3 days, but from the 4-5th day, sample 1 has a pungent smell and was not acceptable while sample 7 was able to retain its aroma and flavor. This is to show that starter culture fermentation was able to improve the shelf life and organoleptic properties for better acceptability.