Immobilization of Alpha Acetolactate Decarboxylase in Hybrid Gelatin/Alginate Support for Application to Reduce Diacetyl Off-Flavor in Beer

Beer production is the largest among alcoholic beverages. Its production process is complex and demands several steps. Lager beers commonly present an off-flavor of butter that is due to the presence of diacetyl, and to avoid such a problem, a long period of maturation (3-5 weeks) is required. Another way is the application of (alpha-acetolactate decarboxylase) ALDC to accelerate the process. The objectives of the present work were to develop a low-cost support using gelatin, a residue from capsules from the nutraceutical industry, to immobilize the ALDC enzyme. For this, the yield, efficiency and activity recovered, and the stability of free and immobilized enzymes at different temperatures and pH were evaluated. To evaluate the capacity of immobilized enzymes when applied directly to beer and their operational stability, three concentrations of glutaraldehyde (1%, 2.5% and 5%) were tested in distilled water as a cross-linking agent. The best results obtained were 95.6%, 27.0% and 23.6%, respectively, for yield, efficiency and activity recovery. Immobilization provided a high activity over a wide pH range. The immobilized enzyme showed greater stability at temperatures of 50 and 60 degrees C. The immobilized derivative showed adequate reuse capacity, and its dehydrated form had excellent activity after long periods of storage.