Physicochemical and Organoleptic Properties of Yoghurt Produced from Cow Milk Supplemented with Soursop (Annona muricata) Pulp

Yoghurt is a globally recognised fermented dairy product valued for its probiotic content and nutritional benefits. The incorporation of tropical fruit pulps into yoghurt formulations offers opportunities to develop functional dairy products tailored to Nigerian consumer preferences. This study evaluated the physicochemical and organoleptic properties of yoghurt produced from fresh cow milk supplemented with soursop (Annona muricata) pulp at concentrations of 0, 5, 10, 15, and 20 percent. Fresh cow milk was obtained from a dairy farm in Vom, Plateau State, and soursop pulp was extracted from ripe fruits purchased from Jos Main Market. Yoghurt was produced using a standardised starter culture protocol. Parameters assessed included pH, titratable acidity, syneresis, viscosity, total soluble solids, and microbiological quality. Sensory evaluation was conducted with seventy-five panellists. Results showed that soursop supplementation at 10 percent yielded a product with a pH of 4.3, titratable acidity of 0.78 percent, and syneresis values comparable to commercial plain yoghurt. Viscosity decreased with increasing pulp concentration, while total soluble solids increased proportionally. Sensory scores for flavour, aroma, and overall acceptability peaked at 10 percent supplementation. The study recommends the 10 percent soursop yoghurt formulation for small-scale dairy enterprises seeking to introduce fruit-flavoured functional yoghurt to the Nigerian market. Keywords: yoghurt, soursop, fermentation, physicochemical, Plateau State.