Resumen de Inhibition of spoilage lactic acid bacteria by lysozyme during wine alcoholic fermentation
G. Lagarde, Jennifer Power, Sue Darius, Zhang Guopeng, Yun Cai Gao, Sheri Krentz
The efficacy of lysozyme against indigenous lactic acid bacteria (LAB) and four inoculated spoilage LAB cultures was investigated in laboratory scale Chardonnay winemaking trials (at pH 3.8). These LAB cultures included Lactobacillus kunkeei, Lactobacillus brevis, Pediococcus parvulus, and Pediococcus damnosus. Three concentrations of lysozyme were used: 0, 125 and 250 mg/L. Alcoholic fermentation of the grape juice was carried out at 20±0.5oC using Saccharomyces cerevisiae. Lysozyme did not have any negative impact on yeast growth and sugar reduction. This enzyme was found to be very effective in inhibiting the growth of all four LAB cultures investigated. Under the given experimental conditions, as high as an 8 log cell reduction was obtained for some of the strains. The acetic acid production by L. brevis and L. kunkeei was significantly reduced in the treatments with 125 and 250 mg/L lysozyme added (P < 0.01). The effect of lysozyme on the cells of the LAB cultures was examined under a scanning electron microscope. It is evident that lysozyme had a detrimental impact on the cells of these cultures. Based on these observations, it is concluded that lysozyme may be a useful tool for winemakers to control the growth of spoilage LAB and to reduce the production of volatile acids. The addition of lysozyme may also prevent the increase of volatile acidity during stuck/sluggish alcoholic fermentation. This tool is particularly useful in high pH wines where SO2 is less effective.
