Lactase in Dairy Processing: Current Advances, Challenges, and Future Directions — A PRISMA-Informed Narrative Review

Abstract

Lactase (β-galactosidase, EC 3.2.1.23) hydrolyses lactose into glucose and galactose and plays a central role in the production of lactose-free and low-lactose dairy products. This review synthesizes peer-reviewed literature published mainly between 2018 and 2026 on lactase sources, mechanisms, industrial applications, limitations, and emerging engineering strategies. Lactase-mediated hydrolysis supports the production of lactose-free milk, yogurt, cheese, ice cream, whey protein powders, and infant formulas while largely preserving nutritional and sensory quality. However, wider industrial application remains constrained by enzyme sensitivity to temperature and pH, high production and purification costs, and inconsistent regulatory thresholds for lactose-free and low-lactose labelling. Recent advances in protein engineering, directed evolution, and enzyme immobilization, including metal-organic frameworks, electrospun nanofibers, and agro-industrial waste-derived supports, have improved thermostability, reusability, and resistance to product inhibition. Combining lactase treatment with ultrafiltration, microencapsulation, and high-pressure processing, alongside whey valorization, offers opportunities for more sustainable and cost-effective production. Key research gaps include limited techno-economic and life-cycle assessments, insufficient consumer-acceptance evidence from underrepresented regions, and the early-stage development of personalized lactase-nutrition approaches. Interdisciplinary research integrating enzymology, process engineering, regulatory science, and consumer research is therefore needed to advance lactase-enabled dairy products globally.