The Effects of Kernel Type (Inshell, Shelled and Split Almonds) on the Growth and Aflatoxin Production of <i>A. flavus</i> Under Different Combinations of Water Activity and Temperature

Almonds are susceptible to infestation by <i>Aspergillus flavus</i>, an aflatoxin-producing fungus. The objective of this study was to investigate the effects of kernel type (inshell, shelled and split almonds) on the ability of <i>A. flavus</i> to grow and produce aflatoxins...

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Bibliographic Details
Main Authors: Barbara Szonyi, Guangwei Huang, Tim Birmingham, Dawit Gizachew
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Toxins
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Online Access:https://www.mdpi.com/2072-6651/16/11/493
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Summary:Almonds are susceptible to infestation by <i>Aspergillus flavus</i>, an aflatoxin-producing fungus. The objective of this study was to investigate the effects of kernel type (inshell, shelled and split almonds) on the ability of <i>A. flavus</i> to grow and produce aflatoxins at different combinations of temperature (20, 27 and 35 °C), water activity (0.85, 0.92, 0.95 and 0.98 a<sub>w</sub>) and incubation period (10, 20 and 30 days). There was no fungal growth at 0.85 a<sub>w</sub> on any of the kernel types. At 0.92 a<sub>w</sub>, only the split kernels supported growth and aflatoxin synthesis. The fungus was able to grow and produce aflatoxins on all three kernels at 0.95–0.98 a<sub>w</sub> and 20–35 °C. At 0.98 a<sub>w</sub>, high total aflatoxin concentrations (>300 µg/kg) were found on the shelled and split kernels at all temperatures. On the inshell nuts, the fungus produced up to 372 µg/kg of total aflatoxins at 0.98 a<sub>w</sub> and 27 °C. Regression analysis showed that significantly higher levels of aflatoxins were produced at 27 °C (as compared to at 20 and 35 °C) on shelled and split almonds. Incubation time was also a significant predictor of aflatoxin accumulation. The results of this study indicated that shipping almonds below 0.85 a<sub>w</sub> and reducing storage time would significantly decrease the risk of infestation and aflatoxin production by <i>A. flavus</i>.
ISSN:2072-6651