Comparative Studies of Ginger (Zingiber officinale) and West African Black Pepper (Piper guineense) Extracts at Different Concentrations on the Microbial Quality of Soymilk and Kunun-zaki

摘要

Extracts of two spices, namely ginger (Zingiber officinale) and black pepper (Piperguineense) were prepared in 0.4%, 1.2%, 2.4% and 3.6% concentrations. Soymilk and kunun-zakiwere treated respectively with the different concentrations and stored at ambient temperature for 5 days. The microbial load and identification were determined every day of storage until samples were adjudged spoilt. On the first day, 0.4% ginger extract in soymilk and kunun-zaki had a microbial load of 7.77 x 10~(6b) and 5.17 x10~(6b) respectively. 3.6% ginger extract in soymilk and kunun-zaki recorded 3.73 x 10~(6b) and 3.30 x 106 each. 0.4% black pepper extract in soymilk had 6.273 x 10~(6b) and recorded 4.63 x 10~(6b) in kunun-zaki. 3.6% black pepper extract in soymilk andkunun-zaki had a microbial load of 3.20 x 10~(6d) and 2.90 x 10~(6c) respectively. On the third day the microbial load increased for both ginger and black pepper extract. Ginger extract recorded 9.13 x 10~(6b) in soymilk and 5.60 x 10~(6b) in kunun-zakiat 0.4% concentration. Black pepper extracts recorded 7.43 x 10~(6b) in soymilk and 3.27 x 10~(6b) in kunun-zaki also at 0.4% extract. 3.6% black pepper extract recorded 4.10 x 10~(6a) in soymilk and 2.20 x 10~(6c) in kunun-zaki. There was linear reductic of microbial load as spice concentration increased. Black pepper recorded lower microbial load, thus having more antimicrobial activity and may be preferred to be used as natural antimicrobial preservatives to extend the shelf-life of food.