The Column - March 2008 - (Page 10)

Riponi, Chinnici and Roemling The Column www.thecolumn.eu.com March 2008 HPLC Analysis of Lysozyme in Different Types of Wine 1University Claudio Riponi,1 Fabio Chinnici1 and Regina Roemling,2 of Bologna, Food Science Department, Bologna, Italy, 2Tosoh Bioscience GmbH, Stuttgart, Germany. Lysozyme, occurring in hen’s egg white, is used in winemaking to eliminate lactic acid bacteria and to control malolactic fermentation. As eggs and derivatives are regarded as potential allergenics the European Commission issued a directive that wine labels must include information about egg derived ingredients such as lysozyme. As a consequence the International Organization for Wine and Vine (OIV) published a standard method for the measurement of lysozyme in wine by HPLC, which is based on a method developed at the University of Bologna, Italy. “A bottle of wine contains more philosophy than all the books in the world.” It was Louis Pasteur (1822–95), the famous French chemist and microbiologist, who stated this. Wine was one of his early objects of study and he solved the mystery of fermentation when he identified and isolated the specific microorganisms responsible for normal and abnormal fermentations in winemaking. His work remains to be the basis of today’s winemaking technology. The Role of Egg Lysozyme in Winemaking Lysozyme (E.C. 3.2.1.17) isolated from egg whites has a long tradition as an antimicrobial agent used in the food industry.1 It is an enzyme with muramidase activity, which degrades the cell wall of gram-positive bacteria such as Oenococcus, Pediococcus and Lactobacillus. In the past it was used mainly as a preservative in cheese making to prevent spoilage by microorganisms. Although microorganisms are mostly regarded as food spoilage some are essential for fermentation processes. During winemaking the primary fermentation process converts the grape sugar to alcohol by yeast. The so-called malolactic fermentation occurs shortly after the end of the primary fermentation. Lactic acid bacteria convert L-malic acid, to L-lactic acid in such a way that they act as biological deacidifiers. Hence, in red wines, malolactic fermentation could result in a more balanced wine, whereas for white wines, where the acidic notes should be preserved, its intervention should often be avoided. A tight control of this process is, however, necessary because the onset of malolactic fermentation in the bottle is undesirable as the process could proceed to further metabolize other acids (citric and tartaric acids), thus increasing acetic acid amounts. Furthermore, the wine will appear to still be fermenting to the consumer, may also lose its flavour integrity and take on an unpleasant lactic aroma. Control of Malolactic Fermentation In the past, cooling and the anti-microbial agent, sulphur dioxide, were used to inhibit the growth of lactic acid bacteria. Sulphur dioxide can provoke allergic reactions such as 10 Authors: Claudio Riponi, Fabio Chinnici and Regina Roemling Contact: regina.roemling@tosoh.com http://www.thecolumn.eu.com

Table of Contents for the Digital Edition of The Column - March 2008

The Column - March 2008
Contents
News
Zosimus - Never Mind the Selectivity - Look at the Plate Count!
HPLC Analysis of Lysozyme in Different Types of Wine
Market Trends & Analysis
A Holistic Approach to Increasing Analytical Throughput on a Modern Gas Chromatograph
If It's Broke, Fix It - Q&A
The Applications Book
LC World Talk - Shimadzu's Newsletter for the HPLC Global Community
LC World Talk Contents
Applications of Ultra Fast HPLC
The World's Most Advanced Liquid Chromatograph
2D-HPLC for Bioanalysis "Co-Sense for BA" System
Metabolite Identification Software

The Column - March 2008