The production of volatiles by fungi when colonizing grain has been quantified and the key components identified in vitro and in situ (Kaminski et al 1974; Magan and Evans 2000; Schnurer et al. 1999). Key volatiles indicative of spoilage include 3-octanone, methylheptanone, 2-methyl-1-propanol, cyclohexanone, trimethylbenzene, undecane, naphthalene, and dodecane. Previous in situ studies have demonstrated that measurement of such volatiles show promise in early detection of deterioration of grain in stores (Tuma et al. 1989). The rapid development of electronic nose technology, which uses a variety of sensor arrays for giving qualitative information on changes in patterns of volatile production, has enabled this technology to be examined in detail for practical applications in the grain commodity chain. Evans et al. (2000) demonstrated that it was possible to classify grain samples in real time into categories of good quality, molded, or suspect grain using an automated computer controlled system coupled with radial based models. The potential for using odor classification from grain as a spoilage indicator has also been demonstrated (Magan and Evans 2000). Work has also shown that e.nose technology could be used for differentiating between different isolates of the same spoilage species on the basis of qualitative volatile production patterns, which may differ due to specific biosynthetic pathways for isolates producing mycotoxins in Fusarium section Liseola species (Keshri and Magan 2001); and in naturally contaminated grain samples (Olssen et al. 2002).
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