Occurrence of aflatoxins in edible vegetable oils in Sri Lanka

Abstract

Aflatoxin contamination in edible vegetable oils is a global concern due to the harmful effects of aflatoxins on human health. This study reports the status of aflatoxin contamination in seven edible vegetable oil types obtained from Sri Lankan market: coconut oil (n = 32), palm olein (n = 5), sunflower oil (n = 5), sesame oil (n = 5), olive oil (n = 5), soya bean oil (n = 4) and corn oil (n = 3). Coconut oil included locally produced branded products (n = 16) and unbranded products (n = 16), whereas the other vegetable oils included only the branded products, most of which were imported. Coconut oil is the most widely used vegetable oil type in Sri Lanka. Total aflatoxin level in samples was determined using Enzyme-Linked Immunosorbent Assay (ELISA), and the positive samples (i.e., total aflatoxin concentration > 1 μg/kg) were further analyzed using High-Performance Liquid Chromatography with fluorescence detection to determine the concentrations of aflatoxins B1, B2, G1 and G2. Out of the 32 coconut oil samples, 12 (37.5%), which included 5 brands and 7 unbranded products, had total aflatoxin contamination and aflatoxin B1 contamination in the ranges of 2.25–72.70 μg/kg and 1.76–60.92 μg/kg, respectively. Out of these 12 samples, 10 and 11 samples exceeded the European Union's maximum permissible levels applicable for total aflatoxins (4 μg/kg) and aflatoxin B1 (2 μg/kg), respectively. All positive coconut oil samples were regular coconut oils, which had been extracted from copra (dried coconut kernel). Aflatoxin contamination in other vegetable oil types and virgin coconut oil was below the limit of detection of the ELISA (0.8 μg/kg). All positive coconut oil samples contained aflatoxins B1, B2 and G1, with aflatoxin B1 being the predominant type, but aflatoxin G2 was not detected in any of the samples. High levels of aflatoxin contamination in coconut oil may have resulted from improper practices during the copra production that facilitate toxigenic fungal growth on copra. Our results suggest that certain coconut oil products available in Sri Lanka may pose a health risk to consumers.