【作者】 朱振宝；

【导师】 田呈瑞；

【作者基本信息】 陕西师范大学 ， 食品科学， 2004， 硕士

【摘要】 核桃是最古老的树生坚果之一，其历史可追溯到公元前7000年。中国核桃栽培面积居世界第一，产量居第二，年产核桃20多万吨。随着西部大开发战略和退耕还林政策的实施，核桃的栽培面积和产量将会大幅度增加，因此开展核桃的加工增值技术研究具有重要的意义。 核桃的油脂含量一般在60％左右。核桃油脂中的脂肪酸主要是油酸（C18：1）、亚油酸（C18：2）、亚麻酸（C18：3）。核桃油脂的脂肪酸主要是不饱和脂肪酸，其对血清脂质健康有利，与其它坚果相比，核桃油脂的独特之处在于其同时富含ω-3和ω-6多不饱和脂肪酸（PUFA）。流行病学研究和临床营养实验表明：经常食用核桃会降低冠心病的发生率。核桃同时富含V_E、膳食纤维、Mg、K，精氨酸等重要营养物质。因此核桃长久以来一直被视为健康食品，在发达国家，核桃油作为功能油脂，受到了越来越多消费者的欢迎。 由于核桃油脂中的不饱和脂肪酸含量高，与其它油脂相比，核桃油脂极不稳定。因此在核桃油脂的加工与储存过程中，必须采取技术措施防止其氧化。V_E是一种天然抗氧化剂，同时具有重要的生理功能。微胶囊是现代高新技术，可以通过壁材的包埋作用保护油脂。因此本试验希望通过微胶囊化包埋和添加V_E来改善和提高核桃油脂的氧化稳定性。 本试验主要研究了不同提取方法对核桃油脂的产率和品质的效果；用气相色谱与液相色谱分别分析了不同方法提取油脂的脂肪酸组成和V_E组成；用Rancimat仪研究了不同方法提取油脂的氧化稳定性；通过喷雾干燥工艺，制备了品质特性良好的V_E复合微胶囊产品。试验结果有助于选择适当的核桃油脂提取方法，并保持良好的品质。试验得到了以下结果： 1．三种提取方法中，核桃油脂产率的高低依次为：溶剂浸出法＞超临界CO₂萃取法＞压榨法；压榨法核桃饼中残留油脂含量较高；压榨法核桃饼是一种优质蛋白质来源，其粗蛋白含量高，氨基酸组成合理，有待于开发与利用。 2．超临界CO₂萃取核桃油脂是一种新型的先进工艺，其所得油脂具有色浅、酸价、皂化价、过氧化价低等特点，其品质明显优于其它两种方法所得油脂。超临界CO₂萃取核桃油脂的影响因素为：夹带剂＞萃取压力＞CO₂体积，在试验条件下，萃取温度影响不大。 3.核桃油脂SCF一CO:萃取的工艺条件为:萃取压力30MPa，萃取温度35℃，萃玲叨寸间3.5h，co:流量巧一ZOk留h。夹带剂为无水乙醇，其用量为投料量的质量分数的10% 4.三种提取方法对核桃油脂的脂肪酸组成与含量无明显影响，试验结果显示:核桃油脂的脂肪酸组成主要为棕搁酸（C16:o）、硬脂酸（C18:O）、油酸（C18:1）、亚油酸（C18:2）、亚麻酸（C18:3），其中不饱和脂肪酸（USFA）在90%以上，多不饱和脂肪酸（P UFA）在75%以上。 5.三种提取方法获得核桃油脂VE的含量依次为:溶剂浸出法>压榨法>SCF一COZ萃取法;在VE组成中，主要以Y一VE为主。 6.三种提取方法获得核桃油脂磷脂的含量依次为:溶剂浸出法>压榨法>SCF一CO:萃取法;氧化稳定性依次为:溶剂浸出法>压榨法>SCF一CO:萃取法;试验结果显示:核桃油脂氧化稳定时间（051）较短，容易氧化。 7.最佳的复配乳化剂配方为:单甘酷（犯%）十蔗糖酷（30%）+Span60（20%）+Tween60（18%），核桃油一水体系的HLB值为8.1。 8.乳化液制备的工艺条件为:复配乳化剂用量2.0%，卵磷脂用量0.4%，乳化温度65℃，加水量为68%。 9.微胶囊制备的最佳壁芯比为1.25:1，较优的壁材组成为大豆分离蛋白（45%）+麦芽糊精（45%）+p一CD（10%）+黄原胶（0 .5%），核桃油脂的包埋率可达70%左右。 10.添加0.02%VE，通过喷雾干燥，造粒工艺的微胶囊化方法可以提高和改善核桃油脂的氧化稳定性，可以制备品质特性较好的核桃油脂与VE复合微胶囊产 口口口。更多还原

【Abstract】 Walnuts are one of the oldest tree nut of the world. China is the first cultivated area of walnut tree and the second yield of walnut country in nowadays, which produce approximately more than 200,000t walnut every year. With the Strategy of Developing the West Region, the yield of walnut and the cultivated area of walnut tree will increase quickly in the near future. Therefore, it is necessary to study on the walnut processing technology.Walnut kernels generally contain about 60% of oil. The major fatty acids found in walnut oil are oleic (C18:l), linoleic (C18:2) and linolenic (C18:3) acids. Walnut fat is mostly unsaturated, and unsaturated fatty acids have been associated with beneficial effects on serum lipids. Compared with other nuts, a unique aspect of walnuts is that they are a rich source of both omega-6 (ω-6) and omega-3 (ω - 3) polyunsaturated fatty acids (PUFA), which are essential dietary fatty acids. Epidemiological and clinical trials suggest that frequent walnut consumption is associated with a decrease in coronary heart disease (CHD). Furthermore, walnut are a rich source of vitamin E , fiber, magnesium, potassium, and arginine. So the walnut is believed to be healthy food for a long history. The walnut oil, as a kind of functional edible oil, becomes mor; and more popular in the developed country.On the other hand, the walnut oil is relatively unstable compared to other common plant oils, which can be ascribed to its high content of PUFA. It is important to prevent the walnut oil from oxidation during the process and storage period. Vitamin E is a natural antioxidant as well as has important physiological effects. Microencapsulation is a new Hi-Tech, which the oil can be protected by the wall materials encapsulation effect. So we expect to microencapsulate the walnut oil with VE and improve its oxidative stability.Specific objectives of the study were 1) investigate effect of different extraction methods on walnut oil quantity and quality. 2) analyze fatty acids profile of walnut oils with different extraction means by GC and VE profile by RP-HPLC.3) investigate stabilities of 3 walnut oil by Rancimat apparatus.4) microencapsulate the walnut oil with VE and produce fat powders. These data may help we select proper extractiontechnology for walnut oil and keep its quality. The results of the experiments are listed as follow.1 In comparison with 3 ways of extraction, the production of walnut oil is putted in order: solvent extraction >SCF-CO2 extraction>screw press extraction. The oil cake contains high content of residue oil(16.5%) and richs in crude protein, which is a good source of protein and should be utilized.2 Extracting walnut oil with SCF-CO2 is a new kind of advanced technology. Compared with two other means, the obtained oil has the following several traits: the light color, the low acid value, the low sponification value, the low peroxide value and so on . The quality of this oil is obviously superior to the other two kinds of oils.3 The parameters of extracting walnut oil with SCF-CO2 is the following: the press,30Mpa; the temperature,35 ℃; the extraction time ,3.5h; the rate of CO2 flow, 15-20kg/h;The cosolvent is free-water C2H5OH and the employing quantity is 10 % of the overall used raw material.4 The 3 different ways have not obvious effect on the fatty acid profile of walnut oil .The results of the experiment indicate that the major fatty acids in walnut oil are palmitic(C16:0),stearic(C18:0),oleic(C18:l),linoleic(C18:2),linolenic(C18:3) acids. In which, USFA account for more than 90% of the total fatty acids, and especially PUFA account for more than 75 % of the total fatty acids.5 The content of tocopherol in walnut oil obtained from the 3 ways is sequenced: solvent extraction > screw press extraction > SCF-CO2 extraction. The Y -VE is predominant VE in the VE profile of walnut oil.6 The content of phosphatide in walnut oil obtained from the 3 ways is sequenced: solvent extraction > screw press extraction > SCF-C02 extraction. The stabiliti更多还原