Volatile Flavor Compounds Produced by Molds of Aspergillus, Penicillium, and Fungi imperfecti

Abstract

Strains of molds Aspergillus niger, A. ochraceus, A. oryzae, A. parasiticus, Penicillium chrysogenum, P. citrinum, P. funiculosum, P. raistrickii, P. viridicatum, Alternaria, Cephalosporium, and Fusarium sp. were grown on sterile coarse wheat meal at 26 to 28 C for 120 h. The volatiles from mature cultures were distilled at low temperature under reduced pressure. The distillates from traps-40 and-78 C were extracted with methylene chloride and subsequently concentrated. All the concentrates thus obtained were analyzed by gas-liquid chromatography, mass spectrometry, chemical reactions of functional groups, and olfactory evaluation. Six components detected in the culture distillates were identified positively: 3-methylbutanol, 3-octanone, 3-octanol, 1-octen-3-ol, 1octanol, and 2-octen-1-ol. They represented 67 to 97% of all the volatiles occurring in the concentrated distillate. The following 14 components were identified tentatively: octane, isobutyl alcohol, butyl alcohol, butyl acetate, amyl acetate, octyl acetate, pyridine, hexanol, nonanone, dimethylpyrazine, tetramethylpyrazine, benzaldehyde, propylbenzene, and phenethyl alcohol. Among the volatiles produced by molds, 1-octen-3-ol yielding a characteristic fungal odor was found predominant.

Effect of koji fermentation on generation of volatile compounds in soy sauce production

“…The main volatiles generated from lipid oxidation were (E)-2-octenal, 1-octen-3-one, 5-methyl-3-heptanone, 3-octanol and 1-octen-3-ol in harvested koji. Most of these compounds increased rapidly from 36 to 48 h of fermentation, during which spore generated significantly (Bull et al, 1985), indicating that the changes in the C 8 aliphatic compounds were related to spores of A. oryzae in soy sauce koji (Kaminski et al, 1974). These C 8 aliphatic compounds, which might be formed by the oxidation of linoleic or linolenic acids, had been regarded as the major contributors to the characteristic flavour of moulds and mushrooms (Kaminski et al, 1974;Cho et al, 2006).…”

“…These C 8 aliphatic compounds, which might be formed by the oxidation of linoleic or linolenic acids, had been regarded as the major contributors to the characteristic flavour of moulds and mushrooms (Kaminski et al, 1974;Cho et al, 2006). Furthermore, the average contents of these flavour compounds in the koji decreased in the order: 1-octen-3-ol (12.72%) > 3-octanol (0.95%) > 2-octen-1-ol (0.22%), which was similar to a report involved in flavour of moulds by Kaminski et al (1974). However, there were no significant changes (P > 0.05) for long-chain aldehydes (hexanal, octanal, nonanal, decanal), which could be produced by lipid oxidation and degradation during fermentation (Lee & Ahn, 2009).…”

“…Ito et al (1990) suggested that the growth rate of koji mould affected the composition of volatile compounds, and eight alcohols, three aldehydes, five ketones and one ester compounds have been reported in rice koji. Kaminski et al (1974) analysed the volatile flavour compounds produced by specific moulds (Aspergillus, Penicillium and Fungi imperfecti) and suggested that 1-octen-3-ol was a predominant fungal volatile compound. However, there were some individual reports about the changes in aroma compounds during soy sauce production.…”

Review of bioaerosols in indoor environment with special reference to sampling, analysis and control mechanisms

“…Penicillium species with spores of 2 to 3 μm (mm) have apparently been responsible for several hypersensitivity pneumonitis epidemics (Kreiss and Hodgson, 1984). The "moldy" or "mildew" odors in some indoor environments are associated with low levels of volatile organic compounds (VOCs) in the air produced by fungi (Kaminske et al, 1974). Health effects have not been directly attributable to these VOCs to date, but the VOCs and/or the organisms which produce them may be contributory factors to complaints of headache, eye and throat irritation, nausea, dizziness, and fatigue in subjects occupying contaminated interiors (Burge, 1990a).…”

Fungal volatile organic compounds show promise as potent molluscicides

“…[21][22][23] Most notable are 1-octen-3-ol, 3-octanone and 1-octene, which are produced by a wide range of fungi including saprophytic molds, mushrooms and entomopathogenic fungi including species of Beauveria and Metarhizium. [24][25][26][27][28] Exactly why entomopathogenic fungi produce these compounds is unclear but the fact that so many insects exhibit avoidance behavior suggest that they are responding to VOCs. 20,29 This paper reports that these compounds are highly repellent or toxic to slugs and snails.…”