Production methods, physico-chemical properties and microbial quality of bongo, a fermented milk product produced in Pallisa District

Abstract

Production of fermented milk products using traditional methods has been carried out since time immemorial across the world. One of such products is bongo, a yogurt-like traditionally fermented dairy product produced and sold in Uganda. The quality of bongo sold in Uganda is not known and this has greatly affected its commercialization. This study was carried out in Pallisa district to characterize the production of bongo by documenting the processing methods, determining its physico-chemical, hygienic quality and the lactic acid bacteria diversity therein. A survey using focus group discussions to identify renowned traditional bongo processors (TBPs), key informant interviews with the TBPs and observations were carried out. Household bongo samples were collected from the bulk fermentation vessels of TBP and analyzed for pH, titratable acidity, total solids and fat content. Total plate, coliform, yeast and mold counts were enumerated on standard media. The lactic acid bacteria in bongo were isolated on agar and then characterized using standard phenotypic traits. The study revealed that two types of bongo are processed in Pallisa district coined ‘beverage’ bongo referring to sour milk that is consumed as a drink and ‘vegetable’ bongo referring to sour butter milk used in cooking traditional sauces. Beverage bongo was made from boiled (pasteurized) cow milk whereas the vegetable type was made from (fresh) cow milk. The average pH, titratable acidity, total solid and fat content for drinkable bongo were 3.86 ± 0.34, 1.60 ± 0.53, 7.14 ± 0.26% and 0.83 ± 0.17% whereas those for vegetable bongo were 3.71 ± 0.12, 1.75 ± 0.13, 7.84 ± 0.19% and 0.79 ± 0.35% respectively. The mean total coliform counts were 2.11 ± 2.34 log cfu/ml and 4.83 ± 5.54 log cfu/ml for beverage and vegetable bongo respectively. The yeast and mold counts were 4.29 ± 4.25 log cfu/ml and 4.49 ± 4.35 log cfu/ml for drinkable and vegetable bongo respectively. The lactic acid bacteria identified in bongo belonged to three genera namely Enterococci (81%), Streptococcus (15%) and Lactobacillus (4%). The study reported high microbial contamination of bongo indicating poor processing hygiene thus rendering the product unsafe for human consumption. Therefore, cross contamination of bongo during its production should be minimized.