ศูนย์นวัตกรรมเทคโนโลยีหลังการเก็บเกี่ยว

Soybean lipoxygenase is active on nonaqueous media at low moisture. A constraint to xerophilic fungi and aflatoxin?

GARDNER, H.W., GROVE, M.J. and KELLER, N.P.

Journal of the American Oil Chemistry Society 75: 1801-1808.

1998

บทคัดย่อ

Certain products of the lipoxygenase pathway are detrimental either to the development and growth of Aspergillus species or to aflatoxin production. Since Aspergillus often thrives on ‘dry’ stored grains, the ability of lipoxygenase to catalyse the oxidation of linoleic acid on these ‘dry’ substrates was investigated. A desiccated model system composed for soybean extract, linoleic acid and cellulose carrier was incubated for up to 24 h at four relative humidities raging between 52 and 95% to determine the extent oxidation catalysed by lipoxygenese, compared with heat inacctivated controls. Oxidation in the active samples was much greater than in the controls and oxidation was principally enzymatic. To test the biological relevance of lipoxygenase  activity under these xerophilic conditions, enzyme-active and heat inactivated defatted soy flour amended either with or without 3.5% by weight linoleic acid was inoculated with fungal spores and incubated at 95% relative humidity. Although fungal growth occurred on all treatments, samples inoculated with A. parasiticus showed significantly less aflatoxin in the enzyme-active samples, compared to inactivated flour.