Wine is a complex beverage that undergoes various transformations during the winemaking process. One of the most critical phases during red wine production is malolactic fermentation (MLF), where malic acid is converted into lactic acid by lactic acid bacteria (LAB). This process helps reduce acidity and significantly impacts wine aroma, flavour and stability. However, MLF also produces histamine, a biogenic amine that can cause adverse reactions in some individuals. In this blog, we will explore the mechanisms of histamine production during MLF in wine.
What is histamine?
Histamine is a biogenic amine naturally produced by various microorganisms, including bacteria, yeast and moulds. Histamine is present in many foods and beverages, including wine, cheese and fish. In the human body, histamine plays a vital role in the immune response and is involved in allergic reactions and inflammation. Histamine intolerance is when the body has difficulty breaking down histamine, leading to headaches, flushing, hives and gastrointestinal issues. People who are histamine intolerant should avoid consuming foods and beverages high in histamine.
Histamine production during MLF
During MLF, LAB, such as Oenococcus oeni, convert malic acid into lactic acid, releasing carbon dioxide and other metabolites. One of these metabolites is histamine, formed by the action of histidine decarboxylase, an enzyme that is present in many LAB. The histamine level produced during MLF depends on various factors, such as the strain of LAB used, the temperature and pH of the fermentation, and the presence of other nutrients. In general, LAB that produce high levels of histidine decarboxylase are more likely to produce histamine during MLF.
Implications for wine quality and safety
Histamine is a potent vasodilator and can cause adverse reactions in some individuals, ranging from mild symptoms such as headaches and flushing to more severe reactions such as asthma. The presence of alcohol and other biogenic amines in wine can exacerbate these effects. Therefore, monitoring histamine levels in wine and ensuring they are within safe limits is essential. There are no legal limits for histamine in wine, but countries have suggested upper limits ranging between 2-10 mg/l. To reduce the risk of histamine production during MLF, winemakers can choose to inoculate with commercial LAB strains with no or very low production of biogenic amines, including histamine, instead of doing a natural MLF. When selecting bacteria for production, commercial companies include very low or no biogenic amine production as an important selection criterion. With naturally occurring MLF, one has no control over the specific population and thus their ability to produce biogenic amines. A 2008 study comparing the commercial culture, Enoferm Alpha (Lallemand), with spontaneous MLF in red wines from Rioja found no histamine production by the commercial culture, whereas spontaneous MLF produced an average of 3.85 mg/L histamine. Lallemand also markets the commercial culture as a bacterial starter culture producing no biogenic amines.
Malolactic fermentation is a crucial winemaking process that can significantly impact wine quality and stability. However, it is also a potential source of histamine, a biogenic amine that can cause adverse reactions in some individuals. By understanding the mechanisms of histamine production during MLF and implementing appropriate measures, winemakers can ensure that their wines are safe and enjoyable for all consumers.
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