不同压榨方式澳洲坚果油品质及抗氧化活性比较

Comparison of Quality and Antioxidant Activity of Press-Processed Macadamia(Macadamia ternifolia F. Muell.) Oils

采用螺旋热榨、螺旋冷榨与液压压榨方式制备澳洲坚果油,运用气相色谱-质谱联用技术对其脂肪酸组成进行分析,并以核桃油为对照,对其色差值、质量指标与总酚含量进行测定;同时,以核桃油与芦丁标准品为对照,研究其对羟自由基、超氧阴离子自由基、2’-联氨-双-3-乙基苯并噻唑啉-6-磺酸(2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid),ABTS)自由基的清除能力及还原力。结果表明:不同压榨方式澳洲坚果油中,液压压榨澳洲坚果油品质最佳,其评估色泽的L、a、b值分别为99.78、-1.44、2.99;质量指标酸价、过氧化值分别为0.648 6 mg/g、0.466 8 mmol/kg;含有5种不饱和脂肪酸,总质量分数为83.89%,其中油酸62.66%、棕榈油酸16.75%、亚油酸1.47%;总酚含量为679.11μg/m L。不同压榨方式澳洲坚果油的抗氧化活性与其质量浓度呈正相关,对羟自由基与超氧阴离子自由基有较强的清除作用,具有一定的ABTS+·清除能力与还原力。其中液压压榨澳洲坚果油对羟自由基的清除能力(半抑制浓度(half maximal inhibitory concentration,IC_(50))1.31 mg/m L)与还原力(IC_(50) 14.78 mg/m L)优于热榨、冷榨澳洲坚果油,低于芦丁标准品;对超氧阴离子自由基的清除能力(IC_(50) 0.029 mg/m L)较强,相同质量浓度下优于冷榨澳洲坚果油与芦丁标准品,低于热榨澳洲坚果油与核桃油;对ABTS+·的清除能力(IC_(50) 12.88 mg/m L)高于热榨澳洲坚果油与核桃油,低于冷榨澳洲坚果油与芦丁标准品。相关性分析得出不同压榨方式澳洲坚果油与核桃油中的总酚含量与其清除羟自由基(R=0.951 9,P<0.01)、ABTS+·(R=0.910 7,P<0.01)的能力及还原力(R=0.939 4,P<0.01)之间具有较高的相关性。

Macadamia（Macadamia ternifolia F. Muell.） oils were obtained by spiral hot pressing, spiral cold pressing and hydraulic pressing methods. The fatty acid compositions of the oils were analyzed by gas chromatography-mass spectrometry. The color, quality indexes and total phenolic contents were determined by comparing with walnut oil as a control. The scavenging capacity against hydroxyl, superoxide anion and 2,2＇-azino-bis（3-ethylbenzothiazoline-6-sulfonate free radicals（ABTS^＋·）, and reducing power were investigated by comparing with walnut oil and rutin as controls. The results indicated the quality of the oil obtained by hydraulic pressing was improved compared with those obtained by other pressing methods; color parameters L, a and b values of the oil were 99.78,-1.44 and 2.99, respectively, acid value was 0.648 6 mg/g, and peroxide value was 0.466 8 mmol/kg. The oil obtained by hydraulic pressing contained five unsaturated fatty acids, together accounting for 83.89% of the total fatty acids, including linoleic acid（62.66%）, palmitoleic acid（16.75%） and octadecenoic acid（1.47%）, as well as 679.11 μg/m L of total phenolics. All of the oils showed concentration dependent antioxidant activity, which could strongly scavenge hydroxyl and superoxide anion free radicals and also exhibited scavenging activity against ABTS^＋· as well as reducing power. The hydroxyl free radical（half maximal inhibitory concentration（IC50） = 1.31 mg/m L） scavenging activity and reducing power（IC50 = 14.78 mg/m L） of the oil obtained by hydraulic pressing were stronger than those of other oils but weaker than rutin. In addition, the superoxide anion radical scavenging activity（IC50 = 0.029 mg/m L） was higher than that of cold-pressed oil and rutin but lower than that of hotpressed oil and walnut oil at the same concentration, whereas the opposite was observed for ABTS^＋· scavenging activity（IC50 = 12.88 mg/m L）. Correlation analysis showed that total phenolic contents in macadamia oils obtained by different pressing methods and walnut oil had good correlations with their hydroxyl and ABTS^＋· scavenging capacity and reducing power with R values of 0.951 9, 0.910 7 and 0.939 4（P〈0.01）, respectively.