Dr Effects Of Preservation Methods On Ph, Proximate Composition And Microbial Quality Of Laboratory Scale Tiger Nut Milk Beverage

Abstract

Tiger nut (Cyperus esculentus) milk beverage is a nutritive, energetic and popular drink mostly produced and consumed in Northern Nigeria. However, the beverage has poor shelf-life which hampered its large-scale production and profitability. Big yellow tiger nut was soaked in 3 L of tap water at 60^oC for 6 hours, additives such as coconut, date and ginger were added and blended. The extracted milk was divided into nine portions and subjected to the following treatments pasteurization, sterilization, ultraviolet light, freezing and sodium benzoate. Proximate composition and microbial quality of both the fresh and treated samples were investigated over 9 day storage period. The pH of the milk samples significantly (p<0.05) decreased over the storage period due to microbial activity. Preservation by freezing maintained most of the nutrient content of tiger nut milk whereas all ambient temperature preserved (28 to 32^oC) samples had a significant (p<0.05) decrease in crude fiber and total carbohydrates and a significant increase in crude lipid. The less acidic the products are the higher their bacterial load. The bacterial load for the preserved milk ranged from 5.19±0.06 to 6.84±0.03 log₁₀cfu/ml. The organisms isolated from the samples were Staphylococcus species, Bacillus species, Clostridium species, Saccharomyces species and Rhizopus oryzae. The findings indicate that the excellent keeping quality of tiger nut milk is due in great part to pH.