Conversion of (poly)phenolic compounds in food fermentations by lactic acid bacteria: Novel insights into metabolic pathways and functional metabolites

Abstract

Lactobacillaceae are among the major fermentation organisms in most food fermentations but the metabolic pathways for conversion of (poly)phenolic compounds by lactobacilli have been elucidated only in the past two decades. Hydroxycinnamic and hydroxybenzoic acids are metabolized by separate enzymes which include multiple esterases, decarboxylases and hydroxycinnamic acid reductases. Glycosides of phenolic compounds including flavonoids are metabolized by glycosidases, some of which are dedicated to glycosides of plant phytochemicals rather than oligosaccharides. Metabolism of phenolic compounds in food fermentations often differs from metabolism in vitro, likely reflecting the diversity of phenolic compounds and the unknown stimuli that induce expression of metabolic genes. Current knowledge will facilitate fermentation strategies to achieve improved food quality by targeted conversion of phenolic compounds.

Graphical abstract

Highlights

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  Lactobacilli metabolize phenolics by reductases, decarboxylases, and glycosidases.

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  Separate enzymes convert hydroxycinnamic acids and hydroxybenzoic acids.

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  Current data on esterase activity of lactobacilli in food remains incomplete.

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  The capacity of lactobacilli to metabolize phenolics relates to their phylogeny.

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  Metabolites of lactobacilli may contribute to health benefits of fermented foods.