Lactose removal in dairy products using immobilized on glass plates polyelectrolyte microcapsules with encapsulated β-galactosidase

Abstract

Lactose malabsorption affects a significant portion of the global population, necessitating effective strategies for lactose removal in dairy products. Current enzymatic methods face challenges such as high costs, enzyme instability, and contamination risks. This study introduces a novel system for lactose hydrolysis using β-galactosidase encapsulated in polyelectrolyte microcapsules (PMCs) immobilized on glass plates. Two systems, GP-β-Gal_PDADMAC and GP-β-Gal_PAH, were developed by layering polycations (polydiallyldimethylammonium chloride (PDADMAC) or poly(allylamine hydrochloride) (PAH)) and polyanions (polystyrene sulfonate (PSS)) to stabilize the enzyme-loaded PMCs. Both systems demonstrated comparable lactose hydrolysis efficiency and retained activity across temperature regimes (22–40 °C). Increasing the number of PMC layers and surface area enhanced productivity, particularly for GP-β-Gal_PAH, while reusability tests confirmed operational stability for at least five cycles. The GP-β-Gal_PAH system demonstrated successful lactose removal. With 8 million PMCs, approximately 50 % of lactose was hydrolyzed over 150 h. Increasing the PMC quantity to 32 million proved sufficient to achieve lactose-free dairy product standards (100 μg/mL) or low-lactose product thresholds (10 mg/mL). Optimal conditions for lactose hydrolysis were established as follows: Immobilization using PAH as the polycation (GP-β-Gal_PAH system); Solvent evaporation at 40 °C in a dry-heat chamber (4–6 h); Deposition of a single layer of PMCs; Working surface area of 8 cm²; and Use of ≥32 million PMCs to hydrolyze lactose in 15 mL of a 50 mg/mL lactose solution over 150 h of continuous incubation, where the hourly hydrolysis efficiency was ∼1 % per hour (reaching ∼74 % hydrolysis) initially, decreasing to ∼0.34 % per hour thereafter to achieve full hydrolysis. These findings highlight the potential of PMC-based immobilization as a scalable, cost-effective solution for lactose-free dairy production, addressing both industrial and consumer needs for safe, low-lactose alternatives.