Effects of soybean oil and oxidized soybean oil on the stability of β-carotene

The effects of 1.0%, 2.5%, and 5.0% purified soybean oil and thermally oxidized soybean oil on the stability of 100 ppm β-carotene as a fat-soluble vitamin A and singlet oxygen quencher in isooctane have been studied. The samples were stored under 1000, 2000, or 4000 lx at 20 °C for 2 days and at 50 °C for 16 days in the dark. The β-carotene was determined by high-performance liquid chromatography. The centrifugation and filtration of vegetable mixture, during sample preparation for β-carotene analysis by HPLC, decreased the coefficient of variation from 4.13% to 1.02%. The purified soybean oil and thermally oxidized soybean oil stabilized β-carotene in isooctane under light and in the dark at α = 0.05. The losses of β-carotene, with 1.0% purified oil, 1.0% thermally oxidized oil and without any oil during 48 h under light, were 11.2%, 80%, and 100%, respectively. 100 ppm TBHQ had a protective effect on the stability of β-carotene in isooctane at α = 0.05. The β-carotene stability decreased as the light intensity increased from 1000 to 2000 or 4000 lx at α = 0.05. The stability of vitamins in fruit and vegetable drinks enriched with fat-soluble vitamins and antioxidants during storage can be greatly improved by adding approximately 1.0% high quality non-oxidized soybean oil.