Evaluation of glycidyl fatty acid ester levels in camellia oil with different refining degrees

Abstract

Recently, glycidyl fatty acid esters (glycidyl esters) were found widely spread in processed oils and foodstuffs. In this article, several edible oil samples marketed in China, i.e., extra virgin olive oil, organic flax seed oil, cold-pressed peanut oil, soybean oil, butter, and camellia oil were evaluated using a gas chromatography/mass spectrometry (GC/MS) method and their glycidyl ester levels were compared. Results showed that the glycidyl ester levels of the olive oil, flax seed oil, peanut oil, and butter were below the detection of limit, while the glycidyl ester levels of two camellia oil samples were 32.7 and 20.1 mg/kg, respectively. To further find out the source for the relatively high glycidyl ester level in the camellia oil, camellia oils with different refining degrees were evaluated. Results indicated that the glycidyl ester levels were about 1213 mg/kg in crude camellia oil, degummed camellia oil, deacidified camellia oil, and bleached camellia oil, while the glycidyl ester level in deodored camellia oil was about 27.0 mg/kg. Based on the results, it was suggested that the source of glycidyl ester in camellia oil was from the crude oil and the deodorization step doubled the glycidyl ester level, therefore, it is of significance to eliminate the glycidyl ester in crude camellia oil in order to control the glycidyl ester level in the final camellia oil product.