Nutritional quality of selected commercially available seed oils and effect of storage conditions on their oxidative stability

Abstract

The primary objective of this research was to investigate nutritional composition of soybean, canola, cottonseed, palm and rapeseed oils under and the effect of storage conditions on their oxidative stability. Nutritional quality of selected seed oils was determined in term of fatty acids, tocopherols and tocotrienols compositions, total phenolic, total flavonoids and mineral contents. High resolution gas chromatography (HR-GC) analysis showed the presence of saturated, monounsaturated and polyunsaturated fatty acids having range from 9.21-43.25, 27.01-58.87 and 29.23-57.75 g/100g, respectively in all the oils. High performance liquid chromatography (HPLC) analysis revealed that γ-tocopherol was the major tocopherol followed by α-tocopherol in most of the oils. Spectrophotometric analysis showed that the total phenolic contents were 2.84-14.44 mg/g of oil, measured as gallic acid equivalent and total flavonoid contents were 0.44-1.56 mg/g of oil, measure as quercetin equivalent. Inductively coupled plasma-optical emission spectrophotometer analysis revealed that Mg, Fe and Mn were present in higher concentration ranging from 57.14-114.85, 126.87- 460.06 and 106.85-538.39 μg/ml respectively. For study the effect of various storage conditions on the oxidation parameters, free fatty acid, peroxide value, para-anisidine value, conjugated dienes and trienes values were determined and ranging from 0.48-1.65, 10.65- 40.15 meq/kg, 9.98-33.30, 8.74-28.41 and 3.86-15.02, respectively after 90 days storage. Statistical analysis revealed that various storage conditions exerted significant (p ≤ 0.05) effect on the oxidative stability of selected oils to different extent.