Potential of faba bean lipase and lipoxygenase to promote formation of volatile lipid oxidation products in food models

Faba bean can respond to the need for plant-based proteins for human consumption. The aim of this work was to study the role of lipid-modifying enzymes in faba bean in causing off-flavour compounds during processing. The faba bean exhibited high lipase and lipoxygenase (LOX) activities, with pH optima being 8.0 and 6.0, respectively. Faba bean LOX preferred free fatty acids (FFAs) over triacylglycerols as substrates, and together with other LOX pathway enzymes, it formed specific volatile products, as measured using headspace solid-phase microextraction-gas chromatography. During the preparation of the food models (i.e. the extracts and emulsions), enzymatic lipid oxidation occurred. The inclusion in the emulsions of rapeseed oil, especially of rapeseed oil FFAs, remarkably increased the amounts of volatile products. The largest quantities of products were formed in food models at pH 6.4, which is close to the pH optimum of LOX. Further studies on lipase in food models are needed.