The basidiomycete Pleurotus sapidus (PSA) was grown in submerged cultures with molasses as substrate for the production of mycelium as a protein source for food applications. The volatilomes of the substrate, the submerged culture, and the mycelia were analyzed by gas chromatography-tandem mass spectrometry-olfactometry. For compound identification, aroma dilution analyses by means of headspace solid phase microextraction and stir bar sorptive extraction were performed via variation of the split vent flow rate. Among the most potent odorants formed by PSA were arylic compounds (e.g., p-anisaldehyde), unsaturated carbonyls (e.g., 1-octen-3-one, ( E)-2-octenal, ( E, E)-2,4-decadienal), and cyclic monoterpenoids (e.g., 3,9-epoxy- p-menth-1-ene, 3,6-dimethyl-3a,4,5,7a-tetrahydro-1-benzofuran-2(3 H)-one). Several compounds from the latter group were described for the first time in Pleurotus spp. After separation of the mycelia from the medium, the aroma compounds were mainly enriched in the culture supernatant. The sensory analysis of the mycelium correlated well with the instrumental results.
The white-rot fungus Pleurotus sapidus (PSA) biosynthesizes the bicyclic monoterpenoids 3,6-dimethyl-2,3,3a,4,5,7a-hexahydrobenzofuran (dill ether) (1) and 3,6-dimethyl-3a,4,5,7a-tetrahydro-1-benzofuran-2(3H)-one (wine lactone) (2). Submerged cultures grown in different media were analyzed by gas chromatography−mass spectrometry. The stereochemistry of the formed isomers was elucidated by comparing their retention indices to those of reference compounds by enantioselective multidimensional gas chromatography. The basidiomycete produced the rare (3R,3aR,7aS) and (3S,3aR,7aS) stereoisomers of dill ether and wine lactone. Kinetic analyses of the volatilome and bioprocess parameters revealed that the biosynthesis of the bicyclic monoterpenoids correlated with the availability of the primary carbon source glucose. Spiking the media with 13 C-labeled glucose demonstrated that the compounds were produced de novo. Supplementation studies i.a. with isotopically labeled substrates further identified limonene and p-menth-1-en-9-ol as intermediate compounds in the fungal pathways. PSA was able to biotransform all enantiomeric forms of the latter compounds to the respective isomers of dill ether and wine lactone.
Basidiomycota are
natural sources of aroma compounds.
When grown
in submerged cultures, the fungus Laetiporus montanus (LMO) forms a spicy and meat-like aroma. It thus represents an interesting
candidate for the production of natural savory flavors. To identify
the key aroma compounds of LMO grown submerged in malt extract peptone
medium, the volatiles were isolated by means of automated solvent
assisted flavor evaporation (aSAFE). An aroma extract dilution analysis
was performed by means of gas chromatography-olfactometry coupled
with a flame ionization detector (GC-FID-O). In the aSAFE extract
of LMO, 24 aroma-active compounds were detected. 5-Butyl-2(5H)-furanone (FD 4096), perceived as coconut-like, was determined
as the compound with the highest FD factor. (E,E)-2,4-Decadienal,
(E,Z)-2,4-decadienal, and sotolon were identified
as responsible key compounds for the spicy odor of the submerged cultures.
Moreover, supplementation of the cultures of LMO, Laetiporus
sulphureus, and Laetiporus persicinus with 13C-labeled thiamine hydrochloride resulted in the
formation of 2-methyl-3-(methylthio)furan (MMTF), a compound with
a pronounced meaty flavor. The concentrations of MMTF were further
increased to 19–27 μg L–1 by additional
supplementation of the cultures with ascorbic acid. The results of
this study indicate potential for the biotechnological production
of a meat-like flavor by Laetiporus species.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.