Lactulose production from kashk whey utilizing eggshell as an eco-friendly catalyst.

Kashk whey, high in lactose, offers a sustainable approach to managing whey waste by enabling the production of valuable products. This study focused on the isomerization of kashk whey lactose into lactulose. Various concentrations of eggshell powder (0.6, 1.2, and 1.8 %, w/v) were tested as natural catalysts alongside different heating times (1, 2, and 3 h) to assess their impact on lactulose yield. Results indicated that both the eggshell concentration and heating duration significantly influenced lactulose production, with a maximum lactulose yield of 22.07 % achieved at 1.2 % of eggshell powder after 3 h. Further crystallization using methanol resulted in a lactulose-rich product containing 49.90 % lactulose with remarkable antioxidant and prebiotic properties. The presence of lactulose was verified through Fourier transform infrared spectroscopy, highlighting the potential of this method for producing valuable, therapeutic prebiotic substances while reducing industrial waste.