Production of natural flavor compounds with monokaryotic strains of Pleurotus sapidus grown on Citrus side streams.

BÜRGER, FRIEDERIKE; KOCH M., ; A. OMARINI; KRAHE N.-K; BERGER R.G.; FRAATZ M.A.; ZORN H.

Dijon

Simposio; 16th Weurman Flavour Research Symposium; 2020

and flavor industry, and side-streams of plant raw materials are particularly suitable as substrates. In 2018, about 180 million tons of Citrus fruits were harvested, and the peels were used e.g. for the extraction of pectin and the production of phytochemicals [1, 2]. In the present study, Citrus side-streams were fermented by monokaryotic strains of the edible fungus Pleurotus sapidus. Some of the cultures exhibited a pleasant smell, reminiscent of woodruff and anise, as well as herbal notes. The individual olfactory impressions emitted from the different monokaryotic strains varied in terms of quality and intensity. To evaluate the composition of the overall aroma, liquid/liquid extracts of submerged cultures of a selected monokaryote were prepared, and the volatiles were isolated by solvent assisted flavor evaporation. Aroma extract dilution analyses revealed p-anisaldehyde (sweet, anise- and vanilla-like) with a flavor dilution factor of 218 as a character impact compound. Apart from that, a compound described as herbal, green, and coconut-like contributed to the overall flavor of the cultures. After isolation and structure elucidation by means of high resolution mass spectrometry and NMR spectroscopy, the substance was identified as the acyloin 2-hydroxy-1-(4-methoxyphenyl)-1-propanone for the first time in cultures of Pleurotus sapidus. Besides this substance, the corresponding tautomer was detected in the culture extracts as well. The biosynthetic pathway towards these compounds was elucidated by a series of biotransformation experiments combined with multi-dimensional GC-MS analyses