Optimization of yoghurt production based on the quality of milk on the Ugandan market.

Abstract

Consistency in the quality of yoghurt is challenged by the variation in milk quality and yogurt producers. In Uganda producers try to prioritize the use of high-quality milk to improve the overall quality of yogurt and enhance their competitiveness in the market. This study aimed to investigate the relationships between the milk quality including; constituents, rheological properties, physiochemical properties, and the quality of the resulting yoghurt. Six milk samples with varied properties were used in the production of yoghurt. In this study, response surface methodology (RSM) was employed to optimize the ingredient formulation and processing parameters of yogurt production such as sugar content, stabilizer and amount of starter culture on the quality of yoghurt Besides, the physico–chemical properties such as pH, titratable acidity, viscosity and acidity of yogurt were also analyzed. The analyses show that the varying yogurts have a pH from 4.25 to 4.82, acidity from 0.64 to 2.32 (%), Brookfield viscosity from 680 to 2105 Centipoise and acidity from 0.05 to 0.063% at constant temperature and time during the optimization process. From the analysis of variance, the R2 of all response variables is more than 0.77 that indicates that a high proportion of variability was explained by the model. Based on the response surface 3D plot of the sensory evaluation, the optimum acceptability of the yoghurt was 34.325% syneresis quality index. The properties of the milk samples were first determined using standard laboratory methods, the relationship of quality of the resulting yoghurt with reference to the milk quality was established and the effect of the ingredients on the quality of yoghurt was also determined enabling consistency in quality during production.