Lactic metabolism revisited: metabolism of lactic acid bacteria in food fermentations and food spoilage

• Homolactic metabolism generally generates lactate as main metabolite.
• Pyruvate can be diverted to acetate or acetoin as alternative end products.
• Heterolactic metabolism generates lactate and acetate or ethanol as main metabolites.
• The availability of substrates for cofactor regeneration determines acetate formation.
• Catabolism of arginine and glutamine contributes to acid resistance of LAB.

Sensory properties, shelf life, and safety of a majority of fermented foods are determined by the metabolic activity of food fermenting lactic acid bacteria. This communication reviews major metabolic routes of lactic acid bacteria, and indicates how metabolism is influenced by the environmental conditions or manipulated for improved control of food fermentations. Emphasis is placed on homofermentative and heterofermentative metabolism of carbohydrates, organic acids, and the conversion of amino acids with major impact on food safety and quality. In addition to the role of lactic metabolism in food fermentations, their implications for food spoilage are discussed.

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