Raffinose extract from navy beans decreases fermentation time and enhances overall quality of yogurt.

Abstract

The consumption of pulses is gaining popularity in recent times due to the awareness of health benefits associated with this food group. Despite this awareness, pulses are still not being used. In order to increase utilization, and consumption of this product, different applications are considered. In this research, extracts prepared from navy beans were used to fortify yogurt. The aim of this study was to evaluate the effect of Navy bean extract on the quality of yogurt. Navy bean extracts were prepared using water extraction procedure. Extract was added to 2% reduced fat milk (2.5% -10%). 2% milk and bean extract mixture was pasteurized at 90oC for 10 mins, cooled to 42oC, inoculated with yogurt culture (Danisco YO-MIX 883 LYO 500 DCU), and fermented for 4 - 8 hours at 42oF. Physico-chemical analysis, microbiology, shelf-life study and quantification of raffinose in extracts were determined using standard procedures. The results obtained showed raffinose concentration of up to 2.65g/l in the bean extract. Fortified samples reached the desired pH of 4.6 in 4 hours; there was a significant increase in acidity and decrease in pH 21-day period. A decrease in Total Soluble Solids (TSS) was observed with the addition of extract, however no effect was observed on the viscosity of yogurt. Microbiology results showed a slight increase in mean values for samples fortified with extract compared to control but this increase was not statistically significant over time (P>0.05). Yogurt fortified with navy bean extract was shown to reduce fermentation time. Increase in acidification and decrease in pH levels shows increased probiotic activity thus, overall quality of yogurt was enhanced with respect to acidification and pH levels. Further studies should incorporate different probiotic strains and optimize extract concentrations.