【作者】 冷玉娴；

【导师】 许时婴；

【作者基本信息】 江南大学 ， 食品科学， 2007， 硕士

【摘要】 葵花籽含油量高,富含不饱和脂肪酸(85～90%),其中亚油酸含量占不饱和脂肪酸的60%以上,因此葵花籽油被誉为“高级营养油”,是国际市场上的畅销品。水酶法提油技术的研究由来已久,不同的油料种籽水酶法提油工艺不同,本论文研究了水酶法提取葵花籽油的工艺路线,优化了工艺条件,并对破乳方法、水解液中的蛋白回收与蛋白的功能性质进行了研究。首先研究了适合于葵花籽的水酶法提油的工艺路线,即采用干法粉碎脱壳葵花籽后,按5:1(w/w)的水/籽比加入pH 4.8的0.05 mol/L柠檬酸缓冲液,搅匀成浆料后加入2.5%的复合纤维素酶,酶解过程中的搅拌速度为250 r/min,酶解温度50℃,酶解7 h。离心后将得到的乳状液层进行二次离心,离心力为8000 g,游离油得率接近90%。其次为了进一步提高提油率,探讨了乳状液的破乳方法。通过比较微波、加热、冷冻解冻、静置和超声波等多种破乳方法,发现加热方法破乳效果最好。加热破乳最适宜条件是将乳状液在100℃下加热15 min,8000 r/min离心20 min,此时破乳率达到63.16%。接着,检测了提取所得的葵花籽油的质量。游离油和破乳油的脂肪酸组成均符合国际标准指标,油脂澄清透明,具有葵花籽油固有气味和滋味,除酸值外各项指标均优于国家四级成品葵花籽油标准。然后从水酶法提取葵花籽油后分离得到的水解液中,采用水提醇沉法提取了葵花籽蛋白。水解液经抽滤,真空浓缩至固形物含量为13%,用75%的低温乙醇沉淀,最终得到的葵花籽蛋白粉色泽乳白,蛋白回收率与绿原酸除去率均达80%以上。最后对提取得到的葵花籽蛋白的功能性质和组成、结构进行了测定。葵花籽蛋白变性温度在94℃左右,等电点约为pH=4.5,其吸油能力优于大豆分离蛋白,而吸水能力则低于大豆分离蛋白。与大豆分离蛋白相比,葵花籽蛋白在较低的温度就具有较高的乳化能力和乳化稳定性。葵花籽蛋白的起泡能力初始较高,但泡沫稳定性较差。葵花籽蛋白氨基酸种类齐全,尤其是谷氨酸含量丰富。葵花籽蛋白结构稳定,包含四种不同组分,其中清蛋白为主要组分,占80%以上,球蛋白、谷蛋白和醇溶蛋白含量较少。葵花籽清蛋白相对分子质量分别为51600、43000、37700、32500、21200和13800;球蛋白相对分子质量分别为37700、34300、20000、15700和14400;谷蛋白相对分子质量为14400。更多还原

【Abstract】 Sunflower seed contains a large amount of oil, especially the unsaturated fatty acid (85~90%) of which over 60% is linoleic acid. Therefore the sunflower seeds oil is called“advanced nutritious oil”, and sold well on the international market. Aqueous enzymatic extraction technology has been studied for a long time. The process of extraction is not similar for different oilseeds. In this dissertation, the suitable process and the optimum extraction conditions for sunflower seeds oil were studied, and then the demulsification method, the recovery of sunflower seeds protein from the aqueous solution and the function of this protein were researched.The sunflower seeds oil was produced using enzymatic hydrolysis method. Dehulled sunflower seeds were ground without water, and then added into pH 4.8, 0.05 mol/L citrate buffer, water/seeds ratio was 5:1(w/w). The enzymatic treatment was performed at 50℃with 2.5% the mixture of a cellulase for 7 h with stirring (250 r/min). After the first centrifugation step, emulsion was separated and recentrifuged (8000 g) to get more oil. The oil extractability was about 90%.In order to enhance the oil yield, the demulsification methods have been studied. Comparing different demulsification methods, such as microwave irradiation, heating, freezing, standing and ultrasonic method, the results showed the effect of heating to be the best. The optimum conditions are heating the emulsion at 100℃for 15 min, and then centrifuging it at 8000 r/min for 20 min, the ratio of demulsification was 63.16%. The quality of the sunflower seeds oil was mensurated too. The fatty acid constitution of the sunflower seeds oil was up to the international standard. Except the acid value, the oil with light color and good flavor was superior to the national grade four finished product of sunflower seeds oil.Sunflower seeds protein was extracted from the aqueous solution by water solution and alcohol sedimentation. The aqueous solution was filtrated, and then condensed until the concentration of solid substance got 13%, added 75% alcohol to sedimentate the protein. The ratio of the protein recovery and the chlorogenic acid removing were both over 80%.Determinations of some functional properties and the composition of sunflower seeds protein were also taken. The protein’s denaturalization temperature is around 94℃, pI=4.5. The capacity of absorbing oil is better than that of soy isolate protein, but the capacity of absorbing water is worse than it. Compared with soy isolate protein, sunflower seeds protein had better emulsifying capacity and stability at low temperature. The foaming capacity of the sunflower seeds protein was good, but the foam was not stable. The amino acid composition of the protein was good with high content of glutamic acid. The sunflower seeds protein’s structure was stable and SDS-PAGE revealed that albumin show six bands (51600、43000、37700、32500、21200 and 13800), globin show five bands (37700、34300、20000、15700 and 14400), and glutelin show only one band (14400).更多还原