Effect of preservatives and ultrasonic waves on organoleptic preference levels of milk yogurt respondents in Malang

Conventional yogurt production uses mechanical stirring and milk fermentation. Several factors that affect the quality of yogurt include raw materials and fermentation technology. Yogurt is rich in protein and fat, but it has a short shelf life and is easily damaged. For development, we used ultrasonic waves that could form cavitation waves to form microbubbles and homogenized the mixture so that the reaction occurred more quickly. The aim of the study is to determine the effect of ultrasonic waves and preservatives on the level of respondents' preference for the yogurt's physical properties. The starter bacteria and milk were obtained from a milk cooperative shop in Batu Malang. Yogurt quality was analyzed from the questionnaire concerning the respondent's level of preference which included texture, thickness, aroma, color, and taste. The results show that the presence of ultrasonic waves in the mixing process has an effect on the quality of yogurt. Respondents prefer the physical properties of yogurt, aspect of color, shape, smell, and homogeneity, made with the help of ultrasonic waves. Preservatives (potassium sorbate) can extend the shelf life but carries a minimum influence on the physical properties of yogurt. The yogurt processing with optimum results involves no addition of preservatives but using ultrasonic waves.