Probiotic Viability and Storage Stability of Yoghurt Enriched with Baobab Pulp (Adansonia digitata)

Abstract

Baobab fruit is important as non-timber forest product having a good source of Vitamin C, fiber and minerals although it is underutilized. Incorporation of its pulp to the probiotic yoghurt have significance to the health of human being. Therefore current study was conducted to analyze the physicochemical, microbiological and sensory properties of baobab blended yoghurt and able to cover the objectives which were i) To analyse the nutritional and functional properties of baobab pulp from Makuyuni, Tanzania ii) To determine the optimum levels and viability of baobab enriched probiotic yoghurt formulated from different combinations of starter and probiotic during fermentation and storage. iii) To monitor shelf life and acceptability of the baobab enriched probiotic yoghurt. Parameters analyzed included proximate analysis, vitamin C, minerals (calcium, magnesium, Zinc), beta carotene, fatty acid, sugars and functional properties (foaming, emulsification and gelling capacities) of baobab fruit pulp which was obtained from Tanzania. Yoghurts were prepared by using fresh milk inoculated with starter cultures containing Streptococcus salivarius subsp. Thermophillus and probiotics Bifidobacterium spp and Lactobacillus acidophilus. These were then blended with pasteurized baobab pulp at 0%, 10%, 20%, 30% and 40% to obtain baobab blended yoghurts, and analyzed for physicochemical (pH, viscosity, titratable acidity, total solids) and microbial for 1,7,14 ,21 and 28 days of storage. In addition proximate, minerals (calcium, magnesium, zinc) and vitamin C were analyzed for the prepared yoghurts. Results showed significant difference (p≤ 0.05) between locations was on fat, crude fiber, carbohydrates and fructose. Vitamin C, beta-carotene, protein, ash, moisture, sucrose, glucose, calcium, magnesium and zinc showed no significant difference (p≤ 0.05) among locations which are Kwa Muhindi, Oldonyo Orng’ina and Naitolia camp, Makuyuni area in Tanzania. Emulsification, foaming and gelling properties ranged between 37.9-45.15%, 1.85-6.57% and 11-12% respectively and were significantly different (p≤ 0.05) among locations. Yoghurt showed significant difference (p≤ 0.05) for moisture, crude fiber, carbohydrate, Vitamin C and magnesium while crude ash, fat, protein, calcium and zinc were not significantly different (p≤ 0.05).After 28 days of storage, all yoghurt samples revealed a significant difference (p˂0. 05), decrease in pH value and an increase in titratable acidity, viscosity and total soluble solids. Microbiologically, yoghurts were stable and with satisfactory sanitary conditions for consumption .Survival rate of probiotic on simulated gastrointestinal tract was 22%-52%. Based on sensory evaluation result, the yoghurts enriched with 10% baobab pulp was the most preferred. Results from this study revealed that the composition and nutritional potential of the baobab pulp may be of high interest to health of consumers hence promoting the greater use of wild fruits.