Effect of lipase and lipoxygenase on lipid metabolism and the formation of main volatile flavour compounds in fermented fish products: a review

Lipid metabolism due to lipid hydrolysis and oxidation considerably contributes to the final product quality of fermented fish products and especially impacts its flavour. Lipase and lipoxygenase (LOX) are key enzymes involved in lipid metabolism. Endogenous lipases (lipase from fish muscle and adipose tissue) and/or exogenous lipases (lipase from microorganisms, the added lipase) catalyse the hydrolysis of lipids, producing numerous free fatty acids. LOX in fish gills and skin tissues plays an important role in lipid oxidation. During the catalysis by LOX, polyunsaturated fatty acids having cis, cis-1,4-pentadiene structure are oxidised, finally leading to the generation of flavour precursors or compounds such as alcohols, aldehydes, ketones, esters and acids. The addition of lipase effectively enhances the content of acidic components. Simultaneously, fermented fish products with a start culture capable of producing both lipase and LOX exhibit higher levels of flavour and aroma. In this process, the collaborative action of lipase and LOX generates a rich array of volatile flavour components. This review offers a comprehensive overview of the distinct functions and effects of both endogenous and exogenous lipase, along with LOX, in fermented fish products, as well as their roles in lipid metabolism. The study also explores their effects on the main volatile flavour compounds of fermented fish products. Moreover, the article discusses the prospects of applying lipase and LOX in fermented fish products, highlighting some limitations in current research and offering recommendations for future studies. Endogenous lipases and/or exogenous lipases (lipase from microorganisms, the added lipase) catalyse the hydrolysis of lipids in fermented fish products, producing free fatty acids. During the catalysis by LOX, polyunsaturated fatty acids are oxidised, finally leading to the generation of flavour compounds such as alcohols, aldehydes, ketones, esters and acids.image