In Namibia, Omashikwa traditional fermented buttermilk made with the root of Omunkunzi
(Boscia albitrunca) tree by local farmers is one of the most important rural food products. It
provides nutrition, jobs and generates income for food security for the community. As a
traditional fermented product, it is unusual as it has a viscous consistency and low syneresis.
However, the quality of Omashikwa is inconsistent and is characterized by high acid taste,
low pH, rancid flavour, root taste and smell and contains filth.
In this research, the production process of Omashikwa, physico-chemical properties of the
traditional and laboratory prepared Omashikwa and the role of the root of B. albitrunca tree
in Omashikwa, viscosity, syneresis, microbiology and sensory properties were studied and
compared in order to improve the quality of Omashikwa for wider community use and for
poverty alleviation. Omashikwa was found to have a protein content of about 3.3%, fat 1.6%,
moisture 90%, lactose 4.6%, ash 0.7%, total solids 8.7%, lactic acid 0.9% and a pH of 3.3 The quality of traditionally processed Omashikwa (TO) was compared with the laboratory
processed Omashikwa (LO), which was made without the root. Traditional fermentation was
carried out with raw milk and under rural conditions. After fermentation the milk was
agitated vigorously to churn into butter, whereas LO was made with pasteurized (65ºC/30
min) and filtered milk, and cream was scooped off after fermentation instead of churning. LO
had a significantly (p < 0.05) higher pH (4.44) compared to traditional Omashikwa (pH 3.25),
lower acidity (0.68%) compared to 0.92% of TO. Fat content was higher in LO (2.44% fat)
compared to 1.56% fat in TO. LO was free from filth and had higher viscosity (2.98 Pa.s)
compared to 2.54 Pa.s and lower syneresis (14.4ml/24 ml) compared to 19.6ml/24ml of TO.
It was found that extract from B. albitrunca root showed a low pH of 4.7 and exhibited
bacterial inhibition properties on Total Plate Count Agar ring test. The root appear to
specifically inhibit Escherichi coli, Staphylococcus aureus and Clostridium species. It also
had a high content of soluble carbohydrates (hydrocolloids or gum) (19.4%).
Significant difference (p < 0.05) in total aerobic counts was observed in TO of 6.62 log cfu/g
compared to 8.62 log cfu/g of LO and lower lactic acid bacterial counts, 6.58 log cfu/g
compared to 7.87 log cfu/g of LO. Probably the most affected microorganisms in TO were
the non acid formers, as lower pH of TO and inhibitory compounds in Omunkunzi root could
have reduced them. Coliforms, yeasts and moulds counts were not significantly different
(p<0.05). No pathogenic bacteria were found in either product. The lactic acid bacteria
identified belonged to the genera Lactobacillus (Lb.) (Weissella), Leuconostoc (Leuc.),
Lactococus (Lact.) and Streptococcus (Str.) Twenty representative strains of LAB isolates
were identified to species level; three belonged to the species Lb. delbrueckii subsp. lactis
and two belonged to Lb. plantarum and two to Weissella confusa (former Lb. confuses).
Three belonged to Str. salivarius thermophilus, three to Leuc. lactis, and two to Leuc.
mesenteroides subsp. mesenteroides. Three belonged to Lact. lactis subsp. lactis and two
belonged to Lact. lactis subsp. cremoris.