The chemical and sensorial effects of lysozyme addition to red and white wines over six months' cellar storage

Lysozyme is an enzyme with muramidase activity which can lyse Gram-positive bacteria, including wine lactic acid bacteria. This enzyme provides a practical method for delaying or preventing the growth of Oenococcus oeni and consequently the onset of malolactic fermentation during the vinification of red and white wines. This paper reports the impact of lysozyme on the chemical and sensorial properties of commercially vinified red (Cabernet Sauvignon and Shiraz) and white (Riesling) wines. The addition of lysozyme to these wines had little or no effect on the content of alcohol, free and total sulfur dioxide and titratable acidity, and pH value. The lysozyme retained 75-80% activity in the Riesling wine after six months, however no detectable activity remained in the Cabernet Sauvignon and Shiraz wines after two days. Upon addition of lysozyme to both of the red wines, a rapid initial decrease (up to 17%) in red wine colour density and phenolic content occurred in association with the formation of a light precipitate. The reduction in red wine colour was also noted by the sensory panel. When added to the Riesling wine, lysozyme did not cause an increase in browning over the six month storage time, but did induce heat instability (haze), suggesting that white wines may require protein stabilisation following treatment with lysozyme. Sensory assessment by triangle difference testing revealed that, during the six month storage period, treatment with lysozyme did not cause important changes to either the aroma or palate of the red and white wines tested.