基于ESR信号的α-生育酚对葵花籽油中自由基影响研究

Effect of α-Tocopherol on Free Radicals in Sunflower Seed Oil Based on ESR Signals

摘要:

葵花籽脱色油在高温脱臭过程中易产生反式脂肪酸,降低油脂氧化稳定性。研究了α-生育酚(α-Tocopherol,α-T)添加量对脱臭脱活性成分葵花籽脱色油的氧化特性和脂肪酸组成的影响,并通过电子自旋共振(Electron spin resonance,ESR)技术,检测油脂氧化过程中自由基信号的变化规律。结果表明:α-T最适添加量为1 000 mg/ kg,此时酸值、过氧化值和茴香胺值分别为0. 28 mg/ g、3. 24 mmol/ kg和86. 79。多不饱和脂肪酸含量为67. 38% ,反式脂肪酸含量为0. 39% 。但当α-T添加量为1 500 mg/ kg时,其酸值、过氧化值和茴香胺值分别增长至0. 43 mg/ g、5. 02 mmol/ kg和173. 42,多不饱和脂肪酸含量降低至65. 03% ,反式脂肪酸含量增加至1. 84% 。通过ESR检测发现,随着α-T添加量的增加,自旋总数先下降至8. 12 × 1014,后略有升高。说明在脱臭脱活性成分葵花籽脱色油体系中适量的α-T可以抑制油脂的氧化,而超过一定量后抑制氧化作用减弱。研究结果可为适度保留天然抗氧化剂,以及检控植物油脂加工过程中的质量提供理论支撑。

Abstract:

Sunflower seed decolorised oil is prone to producing trans fatty acids during high-temperature deodorisation, which reduced the oxidative stability of the oil. The effect of α-tocopherol (α-T) addition on the oxidation characteristics and fatty acid composition of sunflower decolorised oil, deodorised and deactivated ingredient was investigated, and the changing law of free radical signals during the oxidation of oils and fats was detected by electron spin resonance (ESR) technique. The results showed that the optimum addition of α-T was 1 000 mg/ kg, at which time the acid value (AV), peroxide value (POV ) and anisidine value ( p-AV ) were 0. 28 mg/ g, 3. 24 mmol/ kg and 86. 79, respectively, the polyunsaturated fatty acid (PUFA) content was 67. 38% , and the trans fatty acids (TFA) content was 0. 39% . However, when α-tocopherol was added at 1 500 mg/ kg, its AV, POV and p-AV was increased to 0. 43 mg/ g, 5. 02 mmol/ kg and 173. 42, respectively, PUFA content was decreased to 65. 03% and TFA content was increased to 1. 84% . By ESR assay, it was found that the total number of spins was firstly decreased to 8. 12 × 1014 and then slightly increased with the increase of α-T addition. It indicated that α-T can inhibit the oxidation of fats and oils in the deodorised and deactivated sunflower decolourised oil system in moderate amounts, while the inhibition of oxidation was weakened after exceeding a certain amount. The research results can provide theoretical support for the moderate retention of natural antioxidants and quality control of vegetable oils and fats during processing.