Cryogel disks for lactase immobilization and lactose-free milk production

This study aims to optimize lactase immobilization onto Fe-chelated cryogel disks. p(AAm-HEMA) cryogel disks were prepared by free radical polymerization and chelated with Fe ions to prepare IMAC material. The lactase immobilization was optimized after characterization by physical analysis. Lactase activity assays were performed with ONPG and lactose substrates. The maximum amount of immobilized lactase was determined as 107.2 +/- 4.3 mg/g at 1.5 mg/mL and pH 4.5. The optimum pH of immobilized lactase was determined as pH 5.0, and the immobilized lactase showed notably higher catalytic activity at pH 3.0 compared to free lactase. The optimum temperature of lactase shifted from 50 degrees C to 60 degrees C, and the immobilized lactase presented higher activity at 60 degrees C and 65 degrees C than the free lactase. Higher thermal activities were achieved for all temperature values after immobilization. The catalytic effectiveness of lactase was not affected, and similar KM values were calculated for lactose. The immobilized lactase lost 29.2% of its initial activity at the end of 70 days, and preserved 64.9% of initial activity after 25-runs. All lactose in milk was hydrolysed by lactase immobilized cryogel disks in 5 h. The lactase immobilized cryogel disks present encouraging opportunities for lactose-free milk preparation in food industry.

Automated summary

This study aimed to optimize lactase immobilization onto Fe-chelated cryogel disks, and found that the immobilized lactase showed higher catalytic activity at different pH and temperature conditions, making it suitable for lactose-free milk preparation.