Effect of Isomaltulose (Palatinose™) on Characteristics of Fermented Milk During Storage Time

Probiotics and prebiotics have recently gained attention in functional food production and the food industry. This study investigated the effect of isomaltulose (ISO) addition after 48 hours of fermentation on the characteristics of milk fermented with Lactobacillus helveticus PTCC1930 and Lactobacillus (L) paracasei ssp. paracasei PTCC1945 during 19 days of cold storage. The impact of ISO on physicochemical properties, microbial population, functional attributes (antidiabetic and antioxidant activities), and sensory characteristics of fermented milk was evaluated. Additionally, the antidiabetic activity of ISO in sodium phosphate buffer (PBS) was assessed based on α-amylase and α-glucosidase enzyme inhibition. The results indicated that the addition of ISO to fermented milk produced with both strains had no significant effect on physicochemical, microbial, antioxidant, or sensory properties. However, in milk fermented with L. helveticus, ISO increased the proteolysis rate from 2.28 to 2.39 mg leucine/mL and enhanced hypoglycemic properties (p<0.05). ISO supplementation increased the inhibitory activity of α-amylase from 15% to 21% and α-glucosidase from 11% to 35% compared to the control by the end of storage (p<0.05). A key advantage of this product was its sustained hypoglycemic activity throughout the storage period. Furthermore, milk fermented with L. paracasei ssp. paracasei containing ISO exhibited stronger α-amylase inhibition (25%) compared to the control (15.49%) (p<0.05). Additional findings demonstrated that ISO in PBS effectively inhibited α-amylase activity, with Line weaver–Burk plot analysis indicating a competitive inhibition mechanism. Overall, ISO in PBS and fermented milk positively influenced hypoglycemic properties. The application of ISO as a hypoglycemic agent in food products shows promise. Additionally, the combination of ISO and L. helveticus in fermented milk presents a novel, nutrient-rich functional beverage with potential applications in diabetes management.