Decreasing Sugar Level by Enzymatic Hydrolysis of Lactose in Fruit Yogurt

Kluyveromyces lactis β-Galactosidase was used to hydrolyze lactose in compound milk that was used for the production of stirred fruit yogurt.Hydrolysis was simultaneously conducted with the fermentation which was done at 38 °C until 4.65 pH was obtained.The sucrose added was decreased to tolerate the sweetness which gained due to lactose hydrolysis.Lactose and sucrose concentration in the recipe issued to study was 4.7% lactose and 7.1% sucrose (w/w).Trial products were produced by reducing the sucrose levels of 5.3% and 5% in yogurt milk with the addition of lactase.For each recipe sensory evaluations were done.For the recipe that contains %5,3 lactose, sweetness showed a nonsignificant difference between the control sample (α = 0.05).At the end of fermentation, lactose was analyzed, and 97.8% lactose conversion was observed.The percentage of sucrose decreased in the recipe which showed no difference was 25%.As a result, for 1 g of hydrolyzed lactose, 0.4 g of sucrose was decreased from the recipe while obtaining the same sweetness.Besides sensory evaluation, shelf-life analysis was also conducted to see how post-acidification was affected by hydrolyzed lactose.pH values in both the control and trial samples were in the acceptance range at the end of shelf life.