Determination of the Mutagenicity of Four Vegetable Oils After Heat Treatment

Abstract

Background: Vegetable oils are used either in the raw state or heated in the preparation of foods worldwide. Due to the nutrition transition, there is increased demand for fast cooked foods or convenience foods which involves the use of heated and repeatedly heated oils. Research has demonstrated that high temperature cooking with oils can result in the formation of mutagenic compounds that on consumption may induce the development of cancers. This study aimed at determining the mutagenic potential of red palm oil (salted and unsalted), frytol (refined bleached deodorized palm olein) and virgin coconut oil after heat treatment. Method: Samples of the four vegetable oils were subjected to repeated heating in a convectional hot air oven at 180 o C for ten minutes holding time and at least five hours cooling intervals between heatings. The Muta-ChromoPlateTM test kit employing the bacteria test strains Salmonella typhimurium TA 100 and TA 98 was used in the determination of mutagenicity. Results: In the S. typhimurium TA 100 experiments, virgin coconut oil and Frytol showed no mutagenic activity unheated. Repeatedly heated Frytol also showed no mutagenic activity. However, unheated salted and unsalted red palm oil samples showed significant mutagenic activity; (p=0.01) and (p=0.001) respectively, in the S. typhimurium TA 100 experiments. However, once heated and five times heated Frytol, and unsalted red palm oil showed significant mutagenic activity (all p-values <0.05) in the S. typhimurium TA 98 experiments. Conclusions: Repeated heating had an effect on the mutagenicity of the vegetable oils in the study. Frytol and virgin coconut oil showed the least mutagenic activity comparatively. Unheated red palm oil (salted and unsalted) on the local market was highly mutagenic, and this has serious health implications.