Comparative study of the effect of dry and wet ginger (Zingiber officinale Roscoe) spice
on the proximate and microbial safety of soybean beverage
Adegbola Oladele Dauda, Olufunmilola Adunni Abiodun*
Department of Home Economics and Food Science, University of Ilorin, Ilorin, Kwara State, Nigeria
original scientific paper
Soybean beverage, most common nutritious local beverage in Nigeria and in the world, is a high protein beverage used as a dairy milk substitute with the limited utilization due to natural or ambient conditions that serve as growth medium for microorganisms. Hence, it has a short shelf life. This study examines the shelf life of soybean beverage preserved with the ginger spice (dried at 70 ˚C, 80 ˚C, 90 ˚C and 100 ˚C, and 2 g and 4 g of fresh/wet ginger respectively) over 7-week period. The samples were (A: plain soybean beverage; B: 200 ml soybean beverage + 2 g of ginger dried at 100 ˚C; C: 200 ml soybean beverage + 2 g ginger dried at 90 ˚C; D: 200 ml soybean beverage + 2 g ginger dried at 80 ˚C; E: 200 ml soybean beverage + 2 g ginger dried at 70 ˚C; F: 200 ml soybean beverage + 2 g fresh ginger; and G: 200 ml soybean beverage + 4 g fresh ginger respectively). The proximate, pH, microbial and sensory analyses of samples ranged as follows: 87.35% – 90.83% for the moisture content; 0.58% – 0.65% ash content; 4.65% – 4.96% protein; 0.10%-0.26% fibre content; 2.06% – 2.98% crude fat and 1.68% – 4.17% carbohydrate, and pH values ranged from 6.2 – 6.5. Microbiological analysis over storage period showed that the control sample ranged from 0.4×106 -8.3×106 cfu/ml, and treated samples from 0.4×106 to 2.4×106 cfu/ml. Low values of the samples treated with dry ginger spice were preserved better than others, probably due to preservative and anti-microbial properties of the spice. Sensory evaluation, carried out by twenty-eight persons, showed that the sample E: (200 ml soymilk+ 2 g ginger dried at 70 ˚C) was most preferred (with respect to taste, aroma and overall acceptability), while there was a significant difference in the appearance of the samples.
Keywords: Soymilk, ginger (Zingiber officinale Roscoe), proximate analysis, microbiological analysis, safety, shelf life, preservation