Microorganisms contribute to the formation of biogenic amines in wines through various metabolic processes. These compounds can have both positive and negative impacts on the sensory characteristics and safety of wines.
Role of Microorganisms in Wine Fermentation
During the fermentation process of winemaking, different microorganisms play a crucial role in transforming grape juice into wine. Yeasts are primarily responsible for converting sugars into alcohol, while bacteria can also influence the final composition of the wine through various metabolic pathways.
Formation of Biogenic Amines
Biogenic amines are nitrogenous compounds that can be produced by some microorganisms during fermentation. These compounds are formed through the decarboxylation of amino acids, specifically histidine, tyrosine, lysine, arginine, and ornithine.
- Some of the key biogenic amines found in wines include histamine, tyramine, putrescine, and cadaverine.
- These compounds can contribute to the flavor, aroma, and color of wines, but they can also pose health risks if consumed in high quantities.
Microorganisms Involved in Biogenic Amine Production
Several microorganisms have been identified as potential producers of biogenic amines in wines. These include:
- Species of lactic acid bacteria, such as Lactobacillus and Oenococcus
- Yeast species, including Saccharomyces cerevisiae and Candida
Mechanisms of Biogenic Amine Formation
The production of biogenic amines by microorganisms involves specific enzymatic reactions that convert amino acids into their corresponding amines. Some of the key mechanisms include:
- Decarboxylation: This process involves the removal of a carboxyl group from an amino acid, resulting in the formation of an amine.
- Aminotransferase activity: Certain microorganisms possess enzymes that can transfer amino groups between different molecules, leading to the synthesis of biogenic amines.
Factors Influencing Biogenic Amine Production
Several factors can influence the formation of biogenic amines in wines by microorganisms. These include:
- Microbial composition: Different species and strains of microorganisms have varying abilities to produce biogenic amines.
- Environmental conditions: Factors such as pH, temperature, and oxygen availability can impact the metabolic pathways involved in biogenic amine synthesis.
- Presence of precursors: The availability of amino acids in the grape must can influence the production of biogenic amines by microorganisms.
Regulatory Considerations
Regulatory agencies around the world have set limits on the levels of biogenic amines allowed in wines due to their potential health risks. Excessive consumption of biogenic amines has been associated with symptoms such as headaches, nausea, and vomiting, particularly in individuals with certain sensitivities or genetic predispositions.
Prevention and Control Strategies
Winemakers can implement various strategies to minimize the formation of biogenic amines in wines and ensure product safety. Some of the common approaches include:
- Monitoring microbial populations: Regular monitoring of the microbial composition during fermentation can help identify potential producers of biogenic amines.
- Controlled fermentation conditions: Maintaining optimal pH, temperature, and oxygen levels can help prevent the overproduction of biogenic amines by microorganisms.
- Use of starter cultures: Inoculating grape must with specific strains of yeast and bacteria can help control the fermentation process and limit biogenic amine formation.
- Depletion of precursors: Pre-fermentation treatments, such as protein fining or filtration, can reduce the concentration of amino acids available for biogenic amine synthesis.