Effects of Preservative Techniques on the Storage Stability of Sorghum Stem Sheath Beverage

Abstract

The effect of different preservative techniques on the storage stability of sorghum stem sheath beverage was studied. A portion of the beverage samples were pasteurized at 75^oC for 15 mins, another pasteurized and refrigerated and the other pasteurized and preserved with 0.1% sodium benzoate and they were studied at ambient temperature 27 ± 3^oC for 3, 14 and 30 days respectively. The proximate composition of the formulated beverage revealed 88.65 – 88.89 % moisture content, 0.050 – 0.092 % protein, 0.003 – 0.009 % fat, 0.32 – 0.44 % ash, 0.10 – 0.18 % fibre, 10.00 – 10.40 % carbohydrate and 10.16 – 10.42 % dry matter. Fortunately, the values of the beverage were not affected under different treatment with storage time. The shelf life studies of the beverage sample revealed that titratable acidity increased while pH reduced with storage time. The microbial load revealed that pasteurization was effective in reducing microbial load and that the combination of pasteurization with preservative had a much effect in lowering the microbial population thus, extending the shelf life of the beverage. The shelf life of the pasteurized (control) kept only for 3 days after which there was development of offensive odour and colour change from deep purple black to black, whereas the pasteurized and refrigerated sample kept for 14 days before microbial spoilage set-in while pasteurized and preserved samples kept for more than 28 days. The absence of coliform bacteria was also noticed throughout the period of storage. It is expected that the data generated in this study will find useful application in non-alcoholic beverage production thus reducing the high consumption of sugar and chemical-laden drinks in Nigeria market.

Keywords: Sorghum, pasteurization, preservative, proximate, shelf life.