Study of two lactases for the manufacture of lactose-free yogurt by K-Lolac enzymatic method

Methods: Two lactase enzymes (NOLA™5500 fit and Ha-lactase™ 5200 – CH HANSEN) were used in pasteurized cow’s milk at 1000 μL under 4 oC for 18 h. The hydrolysis rate was determined using the K-Lolac kit (Megazyme©). Fermented milk was prepared from hydrolyzed milk, and its pH and syneresis were analyzed. Protein enrichment was applied to improve its organoleptic quality. Results: The initial raw milk contained 42.15 g/L of lactose. There was a significant decrease in the amount of lactose following treatment with the two enzymes (p < 0.05). There was no significant difference in residual lactose level and hydrolysis rate of Ha-lactase compared to NOLA (p > 0.05). Lactase-treated samples showed significantly higher syneresis rate compared to control (p < 0.05). Fermented milk made from hydrolyzed milk showed increased syneresis compared to hydrolyzed milk, necessitating protein enrichment, which improved its rheological properties and sensory quality. Conclusion: Ha-lactase significantly improves lactose hydrolysis compared to NOLA fit. Protein enrichment further significantly enhances the texture and overall quality of fermented milk, making it a suitable alternative for lactose-intolerant consumers.