Physico-Chemical, Microbiological and Sensory Characteristics of Papaya Pulp-Milk Blends Fermented with a Probiotic Starter Culture

Abstract

Yoghurt is a popular fermented milk product across the globe. As consumers become more health conscious, there has been rising interest in probiotic yoghurts, fermented with bacteria that can promote human health, as well as yoghurts containing fruit pieces, juice or pulp, which increase the levels of phytochemicals, dietary fibre and some vitamins in the product. Generally, the fruit products are added only up to about 20%. Here we investigated the physicochemical, sensory and microbial properties of analogous fermented products containing milk, but consisting mainly of papaya fruit pulp. Formulations were made at different ratios ranging from 50-100% papaya pulp. Yoghurt (with 0% papaya) was made to serve as the control. Conditions for pasteurization prior to fermentation were optimized for the control of yeasts and molds. The products were fermented with a probiotic culture consisting of Streptococcus thermophilus + Lactobacillus acidophilus + Bifidobacterium spp. Sensory analysis on a 9-point hedonic scale revealed an increase in acceptability of the various attributes with increase in pulp. Formulations containing 80% to 100% papaya fruit were found to be most liked and of comparable quality to the control, having scores of ≥ 7 (ranging from moderately liked to liked very much)) in colour, taste, texture and overall acceptability. Compared to the control, these formulations were found to contain more ascorbic acid, riboflavin, niacin, folic acid, dietary fiber and carbohydrates. The control was however higher in thiamine, protein and fat levels. The products were stable under refrigerated storage (4 ⁰C) for 3 weeks. In conclusion, we found that papaya pulp fermented with a probiotic starter culture, and containing up to 20% milk had good sensory acceptability. The health benefits of such products are worthy of further investigations.