ABSTRACT
This chapter discusses the undesirable outcomes of bacterial metabolism during grape fermentations, and the various wine spoilage scenarios that can result from lactic acid bacteria (LAB) contamination in wine. All wine-associated LAB species will form secondary metabolites as they grow in wine. Citric acid will be metabolized by many LAB during their growth in red and white wines. The metabolism of glycerol by LAB, particularly in red wine, can result in bitterness, often referred to as acrolein taint. Wine-associated LAB cannot always be easily divided into effective or contaminating bacteria. The types of spoilage associated with contaminating LAB in wine range from overtly buttery aromas, vinegary descriptors, through to mousy off-flavor, hints of geranium aromas, or viscous wines, and compounds that may affect the consumer’s health, such as biogenic amines or ethyl carbamate. The sulfur-containing amino acids methionine and cysteine can be metabolized by some LAB species.
