Quality of Wood-Pressed Rapeseed Oil

This study is the first report on the quality indices of Chinese wood-pressed rapeseed oil. Nineteen representative wood-pressed rapeseed oil samples (representing 80% of the factories that produce this oil in China) were collected and investigated for their physicochemical properties (acid value, peroxide value, color value, and oxidative stability index), fatty acid composition, as well as contents of tocopherols, phytosterols, polycyclic aromatic hydrocarbons (PAH), aflatoxin B-1, arsenic, and lead. Significant differences were observed in the quality results of 19 wood-pressed rapeseed oil samples. The acid value, peroxide value, and color values, as well as the oxidative stability index were found in the ranges of 1.10-3.04 mg KOH/g, 0.84-9.34 mequiv O-2/kg, 3.50-5.30 (Y = 35, R), and 4.43-10.34 h (120 degrees C), respectively. Sixteen of the analyzed oil samples had greater than 2% erucic acid. Tocopherols content ranged from 50.93 to 97.54 mg/100 g and phytosterols content ranged from 453.86 to 735.65 mg/100 g. Meanwhile, benzo[a] pyrene and PAH4 were 1.00-13.57 and 7.47-33.55 mu g/kg, respectively. Fourteen samples exceeded the maximum allowable limit of benzo[a] pyrene and PAH4 (chrysene, benz[a] anthracene, benzo[b] fluroranthene, and benzo[a] pyrene) according to the European Union (EU) standards. However, the contents of aflatoxin B-1, arsenic, and lead of the tested oil samples were all in conformance with the EU, Codex Alimentarius, and China national standards. Results showed that more attention should be paid to the problem of high PAH4 contents in wood-pressed rapeseed oil. The inspection and monitoring of raw materials and processing equipment, as well as the establishment of quality standards for the production of high-quality wood-pressed rapeseed oil are necessary.