PHYSICOCHEMICAL AND MICROBIOLOGICAL EVALUATION OF LOCALLY PRODUCED ERGO AND COMMERCIAL YOGHURT SOLD IN ADDIS ABABA, ETHIOPIA

Abstract

The amount of local and commercial yoghurt provided to the urban market, particularly to the capital, has expanded as a result of the dairy processing industries' recent growth. However, the physicochemical and microbial quality of these products is poorly understood. Therefore, this study was conducted to evaluate the physicochemical and microbial properties and antimicrobial susceptibility of pathogenic bacteria from different yoghurt types sold in Addis Ababa. A total of 40 (20 local and 20 commercial) yoghurt samples were collected from markets in Addis Ababa. A random sampling technique was employed to select local yoghurt samples and based on their processing potential a purposive sampling technique was employed for commercial yoghurt samples. Yoghurt samples were analysed for physicochemical (pH, moisture, ash, fat, Total Solid and Solid Not Fat) and microbial quality analyses were performed according to the manual of microbiological analysis for TVBC whereas, Yeast and mould and coliform count were conducted using TEMPO system. Antimicrobial susceptibility test was also carried out using Vitek ® 2 AST-GN96 card and Vitek ® 2 AST-G79 cards. The data were analysed using SPSS version 21 and a p-value <0.05 was considered statistically significant. The physicochemical analysis of both local and commercial yogurt samples was a mean value with respect to moisture (%) 89.88± 0.36 and 89.29± 0.36, ash (%) 0.53± 0.023 and 0.62± 0.03, fat (%) 4.44± 0.52 and 10.66± 0.52, TS (%) 10.12± 0.63 and 5.02± 0.63, SNF (%)7.18± 0.41and 8.10± 0.41 and pH 3.99± 0.06 and 3.88± 0.06. The microbiological analysis indicated that the TVBC of local and commercial yoghurt samples ranged between 9.09-11.47 logcfu/ml and 9.32-11.48 log cfu/ml, respectively. The overall mean CC and YM count of local and commercial yoghurt samples were 3.72± 0.32and 2.81±0.39 and4.48±0.44 and 3.92±0.39 log CFU/g, respectively. The prevalence of E. coli, and Salmonella spp., in the local and commercial yoghurt samples, were found to be 9(45%) and 2(10%), and 5(25%) and 1(5%), respectively. S. aureus wasn’t observed in both local and commercial yoghurt. The anti-microbial susceptibility profile of the isolated organisms E,coli and salmonella were highly resistant to tested antimicrobials. The overall evaluation of yoghurt quality seems to suggest that the market-level and dairy processing industries need to place more of an emphasis on quality assurance