Amnah M.A. Alsuhaibani, Pakistan Journal of Nutrition
Nuts are highly exposed to fungi contamination in the field during transport or storage and this can result in the production of mycotoxins.
The aim of this study was to determine the prevalence and level of aflatoxins (AFB1, AFB2, AFG1 and AFG2), the mold and yeast counts in pistachios, cashews, walnuts, almonds and hazelnuts and the effect of different storage conditions (temperature and storage period) on aflatoxin formation and mold and yeast counts.
One hundred and twenty-five samples of dehulled raw nuts (pistachio, cashew, walnut, almond and hazelnut) were purchased randomly from retail shops in the Kingdom of Saudi Arabia. The samples were first analyzed to obtain an estimation of the aflatoxin levels, mold and yeast counts prior to storage.
The nut samples were then stored for 3 and 6 months at three temperatures:
- Room temperature (25°C),
- 45°C and
- under refrigeration (4°C).
At the end of the storage periods, the samples were again analyzed for aflatoxin content (AFB1, AFB2, AFG1 and AFG2) and mold and yeast counts.
All of the nuts in the study were found to have safe aflatoxin levels before storage according to the European Union, Iranian and Australian/New Zealand food standard codes (<15 μg kg–1).
The aflatoxin levels rose above safe limits in all of the experimental nuts stored for 3 or 6 months at room temperature (25°C) and 45°C.
However, storing the experimental nuts under refrigeration (4°C) allowed the pistachio, cashew and walnut aflatoxin levels to remain within the safe limit for up to 6 months.
Both the almond and hazelnut aflatoxin levels exceeded the standards by 3 months of storage at 4°C and could not be considered safe.
The conclusion is that storing nuts at a low temperature (refrigeration) reduces aflatoxin levels and mold and yeast counts for 3-6 months.
Effects of Storage Periods and Temperature on Mold Prevalence and Aflatoxin Contamination in Nuts
Amnah M.A. Alsuhaibani
Pakistan Journal of Nutrition Volume 17 (5): 219-227, 2018
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