Fate of aflatoxins during almond oil processing

Authors: Mahoney, Noreen; Cheng, Luisa; Palumbo, Jeffrey - Jeff

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2020
Publication Date: 9/3/2020
Citation: Mahoney, N.E., Cheng, L.W., Palumbo, J.D. 2020. Fate of aflatoxins during almond oil processing. Journal of Agricultural and Food Chemistry. 84(1):106–112. https://doi.org/10.4315/JFP-20-229.
DOI: https://doi.org/10.4315/JFP-20-229

Interpretive Summary: The potential for almond oil made from aflatoxin-contaminated almonds to contain aflatoxins has not been studied. We extracted oil from almond reject samples and found aflatoxins present in 17 oil samples derived from contaminated nuts. Aflatoxin concentrations in oil generally correlated with aflatoxin concentrations in the nuts from which the oil came. Oil quality, measured as how oxidized (rancid) the oils were, did not influence the amount of aflatoxin extracted into the oil. Mineral clays and other adsorbents that are used in refining oils for removal of undesirable colors, flavors and aromas were tested as to whether they could remove aflatoxins from contaminated almond oil. The mineral clays Fuller's earth and bentonite removed an average of 96% and 86% of aflatoxins from oil samples, indicating that these types of adsorbents could be effective tools to remove aflatoxins from contaminated oil during refining.

Technical Abstract: Almonds rejected as inedible are often used for production of almond oil. However, low-quality almonds are frequently contaminated with aflatoxins, and little is known regarding transfer of aflatoxins to almond oil during processing. Oil was produced from reject almonds by hexane extraction. Of 19 almond samples that were naturally contaminated with aflatoxins, 17 oil samples contained measurable amounts of aflatoxins, and aflatoxin content of contaminated oil was correlated with aflatoxin content of the nuts. However, oil aflatoxin levels were not correlated with the oxidation level of the oil as measured by percent free fatty acids and peroxide value. Adsorbents used in oil refining were tested for their ability to remove aflatoxins from contaminated oil. Fuller’s earth and bentonite were the most effective, removing 96% and 86% of total aflatoxins from contaminated oil samples, respectively. Treatment with diatomaceous earth, in contrast, had no effect on aflatoxin levels in oil. These results show that oil refining steps using mineral clay adsorbents may also function to remove aflatoxins from contaminated oil.