Effects of Preservatives and Storage Temperature on the Physicochemical, Microbial and Sensory Properties of Sharba-Milk (A Nigerian Indigenous Soft Drink)

Abstract

Storage potential of sodium benzoate (SB) and citric acid (CA) treated and pasteurized Sharbamilk stored for fifteen days under ambient and refrigerated storage were periodically studied. Proximate composition of the raw rice and Sharba milk (fresh)were respectively, moisture, 10.70% and 77.66%; protein, 6.49% and 3.92%; fat, 1.32% and 0.08%; ash, 0.49% and 0.04%; carbohydrate, 80.73% and 18.29% and food energy, (kcal/100g) 360.76 and 89.38. p Hand total soluble solids(TSS) decreased and titratable acidity (TTA) increased progressively during storage, more in the untreated control than in the treated samples. The levels of pH,TTA, total plate count(TPC),mould-yeast count (MYC), Coliform count, and TSS of Sharbamilk (control and treated)varied narrowly at the beginning and were: pH, 4.70-4.74; TTA, 0.31-0.72%; TSS, 16.41% - 16.65%; TPC, 1.02í—102 – 8.20í—102cfu/ml; MYC, 1.60í—102 – 2.31í—102cfu/ml; Coliform count,1.02í—101 –1.38í—101.cfu/ml. TPC, MYC and Coliform counts of the untreated drinks under ambient storage climaxed before 10th day respectively: 3.34í—108,6.24í—107 and 2.52í—102.A combination of SB and CA afforded the best protection from spoilage under refrigerated storage; neither TPC,MYC nor Coli form count exceeded103cfu/ml in these drinks at the end of storage. Coli form activity was suppressed in all the drinks especially the drinks under chilled storage. The taste, flavor and acceptability of the drink sat the end of storage declined from their initial high values at the beginning. It could be concluded that storage life of sharba milk could be extended beyong15 days if treated with a combination of SB and CA coupled with chilled storage.