Anchoring lactase in pectin-based hydrogels for lactose hydrolysis reactions

Abstract

Several enzymes are anchored to solid supports for applications in the food industry as this process helps to increase the enzymatic stabilities, enabling their reuse in dairy food production. In this sense, lactase was anchored in a pectin-based hydrogel and composite hydrogel containing 5 and 10 wt% of eucalyptus residue for the hydrolysis of lactose in aqueous solutions and UHT milk. The anchorage capacity of lactase was greater at pH closer to neutrality, and enzymatic activity of anchored lactase was 86% greater than that determined for the free enzyme. The initial activity of lactase in UHT milk was impaired due to interactions with enzymatic cofactors. However, the anchored enzyme had greater activity in slower lactose hydrolysis reaction, and higher thermal stability. The presence of eucalyptus residue did not significantly affect the lactase anchorage capacity or enzymatic activity under the study experimental conditions. However, eucalyptus residue was important to improving the thermal and mechanical resistance of the solid support. Hydrogels containing anchored lactase were used for six successive lactose hydrolysis cycles without completely losing their enzymatic activity. Thus, pectin-based hydrogels containing eucalyptus residue are potential solid supports for lactase anchorage and lactose hydrolysis in food industries.