Microbiological Studies of Fermented African Locust Bean Cake Stored under Ginger Extract and Ascorbic Acid Treatment

Abstract

Daddawa also known as iru, among the Yorubas in South-west Nigeria, is a popular condiment used as taste and flavour enhancer in soup and dishes in Africa. Daddawa is traditionally produced from locust beans (Parkia biglobosa) seeds. This work was carried out on the preservation of fermented Parkia biglabosa seeds sourced from local producers and laboratory produced. The local and fermented laboratory controlled samples were treated with of Ginger extract 8mg/g and 2.5mg/g of Ascorbic acid. A control experiment was left untreated. The samples were stored at ambient temperature (34ºC and 30ºC) for 30 and 120 days. The analysis consisted of aerobic and anaerobic mesophilic count, Staphylococcus count and Fungal count, detection of Escherichia coli, S.aureus, Salmonella sp, Mucor sp and Rhizopus sp. Contaminant isolates were identified from locally produced, laboratory treated and untreated (Control) using standard procedure.The proximate analysis and organoleptic assessment of the purchased, laboratory treated and untreated (control) locust bean cake were carried out using standard procedure.The treated locust bean cake indicated microbial log reduction at120 days due to the effects of the preservatives; the Control shows microbial Log increase in the untreated locust bean cake.Isolated and characterized bacterial isolates at 30 and 120 days in the treated and untreated locust bean cake was E.coli only isolated in Kwanar yandaddawa, Staphylococcus aureus were isolated in all the purchased Locust bean cake, Salmonella sp was not detected and a predominant fungal genera were Mucor sp and Rhizopus sp. The result indicated 40% elimination of contaminants at Gude,Jogana and Kwanar yandaddawa. The mean proximate composition percentage differences between 30 and 120 days shows nutritional quality of treated locust bean cake. The Organoleptic assessment indicated that the judges rejected control daddawa due to off flavor.