微波预处理火麻籽对油的品质及抗氧化活性的影响

Influence of microwave pretreatment of hemp seed on quality and antioxidant activity of pressed oil

为考察微波预处理火麻籽(Cannabis sativa L.)对油的品质及抗氧化活性的影响,将火麻籽置于微波功率560W条件下预处理7min,冷却至室温后低温压榨制油。结果表明,微波预处理显著增加了油的酸价、过氧化值,降低了油的水分及挥发物含量,使油脂色泽变深,而脱壳处理可使色泽得到明显改善;火麻籽油中检出8种脂肪酸,其中油酸、亚油酸和亚麻酸是主要的脂肪酸,含量分别为13.88%、57.59%、16.33%,n-6/n-3脂肪酸为3.52∶1,是一种脂肪酸平衡合理的植物油;微波预处理不影响油的脂肪酸组成,使油中总酚含量增加1倍,总维生素E和植物甾醇含量分别增加41.99mg/kg和58.68mg/100g;微波预处理火麻籽显著改善了油的氧化稳定性,提高了油的抗氧化活性,与未经微波预处理的压榨火麻籽油相比,微波预处理后油的氧化诱导期延长了1.05h,DPPH自由基清除活力和FRAP总抗氧化能力分别增加8.46和81.85μmol/100g。表明微波预处理是一种适宜于提高火麻籽油品质的预处理方式。

To investigate changes of pressed oil after microwave pretreatment of seeds,hemp seeds were treated with microwaves under 560 W for 7 min at a frequency of 2 450 MHz. After the pretreatment,seed oil was extracted by cold press. Quality and antioxidant activity of oil were consequently measured. Results showed that microwave significantly increased acid values（ AVs） and peroxide values（ POVs）,and decreased moisture content of oil. The color of oil was deeper than that of untreated. Dehulling significantly improved oil color. Fatty acids were detected in oil including 13. 88% oleic acid,57. 59% linoleic acid,and 16. 33% linolenic acid. 3. 53∶ 1 ratio of n- 6 and n- 3 fatty acids was found in oil which was a well- balanced proportion of the 2 essential fatty acids. Microwave had no significant effect on fatty acid composition in oil. Total phenolic content was increased by one fold,total tocopherols and phytosterols contents were increased by 41. 99 mg / kg and 58. 68 mg /100 g respectively. Microwave significantly improved oxidative stability of oil and its antioxidant activity. The induction period（ IP） of oil was increased 1. 05 h,DPPH and FRAP values were increased 8. 46 and 81. 85μmol /100 g respectively. In conclusion,it is recommended to treat hemp seeds by microwaves before cold press for oil.