New Enzymes for the Food Industry
Peroxidases of the Basidiomycete Marasmius scorodonius degrade ß-Carotene and related tetraterpenes. The asymmetric cleavage results in the formation of potent flavours, such as ß-Ionone. At the same time the carotenoids undergo a bleaching reaction which may be used for the gentle enzymatic decolorisation of mass fluxes.
Basidiomycetes secrete peculiar lipases. An enzyme of Pleurotus sapidus accepts bulky substrates, for example Xanthophyll esters, which after successful hydrolysis serve as a substrate for the first mentioned enzyme.
Looking at the natural growth substrate of basidiomycetes (wood, leaves, bark) the abundance of peptidases secreted is surprising. The food industry is using peptidases on large scales for flavour generation, in ripening processes and for total hydrolysis.
All of the enzymes mentioned have been sequenced and functionally expressed in various prokaryotic host strains.
The spectrum of oxidoreductases of basidiomycetes is particularly impressive. Laccases, the fungal counterpart to polyphenoloxidases from plants, degrade environmental contaminants and modify polysaccharides. The enzymatic oxidation of pentosanes using laccases affects the rheology of wheat flour doughs. Thus, food may be furnished with new texture properties. Peroxidases show similar crosslinking reactions in dough.