Physico-chemical Properties of Yoghurt Flavoured with Mmilo (Vangueria infausta) Pulp from Botswana

Abstract

Mmilo (Vangueria infausta) is an edible fruit which is under-utilised in Botswana, often drying up and going to waste in the wild. As a way of embracing sustainability and indigenous value-addition in food production, yoghurt was fermented and flavoured with mmilo pulp. The purpose was to fortify yoghurt with vitamin C through the addition of different amounts of mmilo fruit and to assess the statistical significance of such fortification through physico-chemical assay. Vitamin C content of fortified yoghurt increased by 35-150%, with statistically significant change (P=.05) noted in samples incorporating 2, 4 and 8% of mmilo pulp, and it was predicted that a 200g portion of the product incorporating 4% of pulp could meet dietary requirements of healthy adults for prevention of scurvy. Also, total dissolved solids measured as °Brix, and total titratable acidity both increased significantly from 9.03 to 16.6° and 1.22 to 1.4%, respectively (P=.05) while pH decreased significantly as well, with lowest value recorded as 3.94 in contrast to the control sample whose pH was 4.45. Addition of mmilo pulp significantly changed product colour (P=.05) resulting in reduction in lightness (L*) and green-red hue (a*) and increase in blue-yellow hue (b*). It may be concluded that flavouring yoghurt using mmilo pulp is a viable means of fortifying it with vitamin C and improving its dissolved solids content and, for further development, it is recommended that microbiological profiling and sensory evaluation be conducted to facilitate its commercialization.