Sensory Property, Physicochemical and Bacteriological Examination of Home-made and Commercial Yoghurt Produced and Marketed in Port Harcourt Metropolis, Nigeria

Abstract

Bacterial contamination of yoghurt cannot be overemphasized due to it physicochemical and sensory properties that might encouraged the growth of pathogenic bacteria. This study was done to determine the sensory property, physicochemical and Bacteriological examination of yoghurt made at home for home consumption and the one made and sold in Port Harcourt metropolis by the use of general microbiological techniques. Results gotten showed that sample B (Sweetened Home-made) had the best sensory properties when assessed as 47.6%; 52.5%;47.5%;27.5%;50% 32.5% for overall acceptability, most preferred, appearance/colour, aroma, flavor and texture/viscosity respectively. Proximate composition, mineral and vitamin content revealed that sample F had the best moisture content (87.33%); sample A had the highest ash content (1.73%); sample B had the highest crude protein and carbohydrate content (6.02%; 21.36); Sample C had the highest fat content (2.27%). The result of the iron (Fe) content of the different yoghurt samples revealed that sample C had more iron content (0.777mg/100g). The sodium content was high in sample A (44.875 mg/100g) and least in sample F (1.15 mg/100g). Sample B (216.963 mg/100g) had the highest calcium content while sample B (0.0047 U.I/100g) had the highest vitamin C content as compared to vitamin A content having the highest amount in sample A (0.097 mg/100g). The total heterotrophic bacterial counts ranged from 2.20±0.63x10⁴ to 4.65±2.19x10⁴CFU/ml for sample E and A respectively. The Total lactobacillus count ranged from 2.34±1.94x10² to 12.28±8.76x10²CFU/ml for sample A and F respectively. There was no significant difference (p≥0.05) in the total heterotrophic bacterial and lactobacillus counts between the different milk samples analyzed. Forty-four (44) bacterial isolates were identified in this study belonging to the following genera; Bacillus spp, Staphylococcus spp. and Lactobacillus spp. Bacillus had the highest occurrence in sample B, C, D and F (11.36%) with least occurrence in sample A and F (6.36%). Staphylococcus had the highest occurrence in sample C (9.09) with least occurrence in sample E (2.27%).  Lactobacillus has the highest abundance in sample D (6.82%). This study has revealed high bacterial load, proximate, mineral and vitamin content which might allow bacteria to thrive. There is need to advocate for proper storage of the yogurt to prevent bacterial contamination.