New polyketides, termed veramycins, were isolated along with their known congeners NFAT-133 and TM-123. Total synthesis from a central building block was accomplished, the BGC identified and a biosynthetic pathway for this molecule class proposed.

Brown-rot fungi are particularly suitable for the sustainable and cost-efficient biotechnological production of natural flavors. In this study, Wolfiporia cocos was employed for the fermentation of European black currant pomace supplemented with aspartate in surface cultures to produce a flavor reminiscent of wild strawberries. Aroma dilution analysis (ADA) by means of dynamic headspace extraction was developed as a suitable technique for solid samples. The character impact compounds were quantified by stable isotope dilution analysis and standard addition and validated by recombination experiments. (R)-Linalool (1879 μg kg–1, ADA 211), methyl anthranilate (2206 μg kg–1, 210), 2-aminobenzaldehyde (771 μg kg–1, 25), and geraniol (138 μg kg–1, 25) were identified as key aroma compounds. Recombination experiments demonstrated that the combination of the four analyzed compounds was responsible for the odor impression reminiscent of wild strawberries.

Several non-canonical, methylated terpenes have been described as products of genetically modified Escherichia coli recently, and the aroma properties of 28 odor-active methylated derivatives of prenol, isoprenol, bornane, camphene, carene, citronellol, fenchol, geraniol, limonene, linalool, terpineol, and farnesol were characterized for the first time in the current study. Twelve methylated monoterpenes exhibited a particularly intense and pleasant odor and were therefore chosen for the determination of their respective odor thresholds (OTs) in comparison to their non-methylated equivalents. In addition to the determination of OTs based on the literature value for the internal standard, (2E)-decenal, the threshold values of the compounds with individually determined OTs of the participants were calculated. This enabled a more precise identification of the OTs. Among the non-canonical terpenes, the lowest OTs in the air were found for 2-methyllinalool (flowery, 1.8 ng L−1), 2-methyl-α-fenchol (moldy, 3.6 ng L−1), 2-methylgeraniol (flowery, 5.4 ng L−1), 2-methylcitronellol (citrus-like, 7.2 ng L−1), and 4-methylgeraniol (citrus-like, 16 ng L−1). The derivatives of geraniol, linalool, and citronellol showed very pleasant odor impressions, which could make them interesting for use as flavoring agents in the flavor and fragrance industry.

No abstract