Effect of starter culture fermentation of milk on the production, sensory attributes and storage of Wara (a Nigerian unripened soft cheese)

Abstract

This study investigated the effect of Lactobacillus plantarum and Lactobacillus acidophilus isolated from wara, a Nigerian unripened soft cheese, on the production of starter-mediated type with improved quality and longer shelf-life. Fresh cow milk was pasteurized and inoculated with  standardized cells of Lactobacillus plantarum and o Lactobacillus acidophilus (singly and in combination) and incubated at 30 C for 24 h to ferment. The fermented (acidified) milk was then used to produce wara using juice extract of Calotropis procera as rennet. Viable cell counts and physicochemical properties were estimated in the fermenting milk, while organoleptic attributes of traditional and starter-mediated wara were determined following standard procedures. The wara samples were stored at 30±2 °C for 6 days during which samples were obtained daily for physicochemical and microbiological analysis. Overall, physicochemical analysis of the fermenting milk samples showed a gradual drop in pH, increase in total titratable acidity and diacetyl level with accompanied increase in viable count. Organoleptically, there was no significant difference (p> 0.05) between the traditional and some of the starter-mediated wara. During storage, the starter mediated wara had the lowest bacteria count and extended shelf-life.

Keywords: Wara, Starter culture, Shelf life, Sensory attributes, Fermentation.