Optimization of probiotic Lukom formulation based on grape juice

Lukom is a sort of food that is mainly composed of sugar and starch and, it creates variety in the consumer basket as a snack. Sugar is used as a sweetener in the production of lukom. Grape juice contains high amounts of natural sugars, minerals, vitamins, organic acids and antioxidants, so grape juice can be used as a sweetener as a sugar alternative. In this study, different levels for starch, sugar and grape juice were determined using Design Expert software. For this purpose, 16 treatments were selected using the software for independent variables, including 10-15% starch, 7-35% sugar and 1.5 - 35% was grape juice. The tests included pH, water activity, stiffness, hardness and adhesion force of the tissue and sensory evaluation. Also, after selecting the optimal sample, the survival rate of probiotic bacteria in a fourteen-day period was assessed. The results showed that a linear model was proposed for the trend of all the studied factors so that only the amount of grape juice and sugar was significant for pH. Grape juice and starch also had a greater effect on water activity. With changes in the percentage of starch, sugar and grape juice, the light intensity decreased and the changes in grape juice were more noticeable. The adhesion force and texture stiffness for the independent variables showed the fit between the selected model and the increase in grape juice, stiffness and adhesion of the texture of Lukom samples had a significant increase in the study area. The number of probiotics consumed during the 14-day period was significantly reduced. In the sensory evaluation of the samples, a significant difference was observed between the produced samples and the overall score was calculated to be about 4.1.