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REPRINTS, COPIES
| Adams, G.H. and Z.J. Ordal. 1976. Effects of thermal stress and reduced water activity on conidia of Aspergillus parasiticus. Journal of Food Science 41:547. |
| Purpose: This study examined and characterized the effects of thermal stress and reduced water activity (Aw) on the conidia of Aspergillus parasiticus. |
| Abstract: Conidia of Aspergillus parasiticus(an aflatoxin producer) were harvested from an agar medium, centrifuged, and resuspended in 0.05% Tween-80. The suspension was subjected to a thermal stress of 51C for up to 4 hr. Viability and thermal injury were evaluated by the use of two plating media, yeast extract agar and yeast extract agar + 10% NaCl. Evidence of injury was demonstrated by the difference in colony counts on the two media. The number of injured cells increased as the heating time continued. Colonies from injured conidia developed more slowly than colonies from unheated conidia. The effect of a reduced water activity (Aw) was evaluated by comparing the ability of unheated and heated conidia to grow in media of differing water activities. A most probable number techniqe was used to measure growth. Media of reduced Aw limited the ability of injured conidia to outgrow as compared to unheated conidia. Continued storage of injured conidia in media of reduced Aw eventually resulted in a loss of colony-forming ability. Solutes used to lower Aw were sodium chloride, glycerol, and sucrose. |
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