Effect of Temperature on the Physicochemical and Microbiological Properties of Functional Beverages Formulated from Sorghum bicolor Stem Sheath

Abstract

Sorghum bicolor stem sheath could be a promising raw material for healthy beverages due to its antioxidant potential. However, heat  processing affects the physicochemical and nutritional properties of food products, as well as the shelf stability. This research was aimed  at investigating the effect of temperatures (70, 100 and 121 ^oC) on the physiochemical, microbiological and sensory properties of  functional beverages prepared by steeping S. bicolor stem sheath in hot water at 70°C, 100°C, and 121°C, for 10 minutes. The  physicochemical, microbial and sensory analyses were then carried out. The results were in the range of (1.90 -10.00%) for total solids,  (0.00 – 9.00%) sugar, (0.01-0.05) ash, (5.54-7.00) for pH, (0.03-0.11%) total acidity, and (0.01-0.03 mg/100 g) vitamin A. The protein and  vitamin C were not detected. The mineral elements (mg/L) ranged from (50.30-54.79) for Mg, (20.77-23.00) for Na, (18.54-20.33) for K,  (40.91-52.73) for Ca, (0.11-0.17) for Fe, and (2.50-3.51) for Zn. The microbial loads ranged from (0.00 -22.00) for the total bacterial count,  (0.00 -21.00) for total coliform count, (0.00 -16.33) for total enterobacteriaceae count, and (0.00 -39.00) cfu/ml for total fungi count.  Generally, high temperatures reduced the total solids, ash, and pH, as well as the microbial load but temperature had no effect on the  mineral composition and the vitamin A content. At 121 ºC, the microorganisms in the formulated drinks were eliminated and some  nutritional and sensory parameters were preserved. With appropriate product processing methods, novel healthy functional beverages  can be produced from Sorghum bicolor stem sheath.