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Lysozyme, a muramidase enzyme from egg whites (EC 3.2.1.17), is widely used in soluble form to control lactic acid bacteria in different foods. Moreover, hen egg white lysozyme is a hydrolytic enzyme that can be used to the control malolactic fermentation (MLF) during winemaking. MLF is only desirable in red and in some white wine, this suggest that MLF is at fault and needs to be controlled in all other types of wine. Lysozyme exhibits selective antimicrobial activity based on the hydrolysis of peptidoglycan cell wall constituents in lactic acid bacteria. In the last decade, several studies identified allergic reactions due to the presence of lysozyme in food. Given this relatively high incidence of lysozyme sensitization, and in accordance with the recently changed EC food legislation (1266/2010/CE), the use of lysozyme as an additive has to be declared on the ingredient label. To overcome this problem, the immobilization of the enzyme on insoluble supports, which allows the enzyme to be removed, has been the preferred strategy. In this context, this article offers a review of reports on lysozyme enological use over the last decade. It surveys the immobilization techniques and support materials used for lysozyme food preservation. This study attempts to provide useful guidance from the wealth of available immobilization data in the literature and, more importantly, to develop an integrated perspective on how to customize lysozyme for future enological uses.

The influence of potential inhibitors, naturally present in wine, on the activity of stem bromelain was investigated in order to evaluate the applicability of this enzyme for protein stabilization in white wine. Bromelain proteolytic activity was tested against a synthetic substrate (Bz-Phe-Val-Arg-pNA) in a model wine system after adding ethanol, sulfur dioxide (SO(2)), skin, seed, and gallic and ellagic tannins at the average range of their concentration in wine. All the inhibitors of stem bromelain activity tested turned out to be reversible. Ethanol was a competitive inhibitor with a rather limited effect. Gallic and ellagic tannins have no inhibitory effect on stem bromelain activity, while both seed and skin tannins were uncompetitive inhibitors. The strongest inhibition effect was revealed for sulfur dioxide, which was a mixed-type inhibitor for the enzyme activity. This study provides useful information relative to a future biotechnological application of stem bromelain in winemaking.

a b s t r a c tBromelain from pineapple stem has been studied in unexplored model wine buffer (pH 3.2 tartaric acid and ethanol) in order to evaluate its applicability for white wine protein stabilization.Bromelain proteolytic activity was studied against several synthetic peptide substrates in McIlvaine buffer covering a wide pH range. Among different synthetic substrates, Bz-Phe-Val-Arg-pNA turned out to be the most suitable one to test bromelain activity at the average minimum pH value of wine (3.2). The protease activity was significantly increased by the presence of 5 mM cysteine while no influence was exerted by EDTA. The inhibiting effect of ethanol was investigated in the range 0-25% (v/v), resulting in being rather limited at the average minimum concentration found in wine (10% v/v).The kinetic parameters were estimated in both McIlvaine (as reference) and model wine buffers. This study showed that stem bromelain worked well at the average minimum pH value of wine, and had a significantly higher activity in model wine buffer (K a increased of 42%). These results are the basis for suggesting a future biotechnological application of this protease in winemaking.