The effect of ginger (Zingiber officinale) and green tea (Camellia sinensis) against bacteria growth on soymilk

Abstract

Soymilk contains complete nutrients such as carbohydrates, vegetable protein and vitamin in which our body needs. It also can be used as an alternative food source for lactose intolerant people. At room temperature, soymilk is susceptible to the damage due to bacterial activity. Storage at low temperatures is one of the control measures to prevent nutrient damage of soybean milk. Ginger and green tea are a plant serving as an antibacterials which can be added to the foods and beverages. The purpose of this study was to determine the effect of ginger and green tea powder in inhibiting the growth of bacteria in soybean milk. Soybean milk samples were pure soymilk (original) and soymilk with the addition of ginger and green tea powder. Soybean milk was stored at a temperature of 7 °C for (0, 1, 2 and 3) d. The total number of bacteria was measured using Plate Count Agar (PCA) medium. This study shows that the number of bacteria present in soymilk samples before treatments has not exceeded the limit of total bacterial contamination according to SNI 01-3830-1995 that is 1 × 106 CFU · mL−1. Compared to original soybean milk (sample A) and the addition of ginger powder (sample B), soybean milk with the addition of green tea powder (sample C) has a fewer number of bacteria on day 0. The ability of green tea in inhibiting bacterial growth also occurs on 1 d, 2 d and 3 d. This indicates that the green tea powder has more promising potential to inhibit the bacteria growth in soymilk than ginger. Both can be used as natural food additives and preservatives.