Effect of Boscia Albitrunca (Omukunzi) Root on the Bacteriology and Viscosity of Omashikwa, Traditional Fermented Buttermilk from namibia

Abstract

The objective of this study was to determine the role of Omukunzi root (Boscia albitrunca) in the viscosity or consistency, sensory and bacteriological profile of Omashikwa, traditional fermented buttermilk from Namibia. Omashikwa is a popular traditional fermented buttermilk product made with Omukunzi root among the Owambo and Herero tribes living in the North and Central Namibia. It is processed by fermenting raw milk in the presence of Omukunzi root in a calabash and agitated to obtain butter granules. Butter granules are then removed, washed, salted and made into butter or processed into ghee (butter oil). The remaining fermented milk is Omashikwa or traditional fermented buttermilk. The results of this study indicated that the root of Omukunzi tree had low pH (4.9), exhibited bacterial inhibition properties and had high content of soluble carbohydrates (19.4%). Omashikwa made with Omukunzi root (TO) was more viscous, 2.9 Pa.s compared to 2.5 Pa.s of laboratory Omashikwa made without the root (LO). The total aerobic counts were 6.62 cfu/g for TO and 8.62 cfu/g for LO and lactic acid bacteria (LAB) was 6.58 cfu/g for TO and 7.87 cfu/g for LO and were lower in samples with the root. Coliforms, 2.68 cfu/g (TO) and 2.70 cfu/g (LO) and yeasts and moulds were not significantly different (p≤0.05) and were 1.57 cfu/g for TO and 1.69 cfu/g for LO. Yeasts and mould counts from the gourd swabs were high, 4.78 cfu/g. The LAB identified belonged to the genera Lactobacillus (Lb.), Leuconostoc (Leuc.), Lactococcus (Lact.) and Streptococcus (Strep.). The LAB species identified were Lb. plantarum, Lb. lactis subsp. lactis, Leuc. lactis, Leuc. citreum, Lact. lactis subsp. lactis, Lact. lactis subsp. diacetylactis and Strep. thermophillus. The results indicated that Omukunzi root plays a positive role in the quality of value added Omashikwa in terms of improving consistency, sensory quality and controlling microbial profile which could finally help to increase income, create jobs and improve food security and nutrition to the rural communities.

Key words: Boscia albitrunca, fermentation, buttermilk, Omashikwa, viscosity