【作者】 田其英；

【导师】 华欲飞；

【作者基本信息】 江南大学 ， 粮食、油脂及植物蛋白工程， 2008， 硕士

【摘要】 本文主要研究脂肪氧合酶酶活对脱脂豆粕特征氧化指标的影响,以及脱脂豆粕特征氧化指标与其提取的大豆分离蛋白凝胶性之间的关系。首先通过控制干热处理中加热温度、加热时间以及水分含量三个因素制备含不同脂肪氧合酶酶活的脱脂豆粕。接着研究不同酶活对脱脂豆粕氧化特征指标如TBA值、羰基含量、巯基和二硫键含量的影响,结果表明随着脂肪氧合酶酶活的降低,豆粕氧化程度减小。从不同脱脂豆粕中提取分离蛋白,利用质构手段来测定分离蛋白凝胶强度,通过相关性分析得出:TBA值和羰基含量与分离蛋白凝胶强度相关性系数几乎为0,所以说他们之间没有相关性。巯基含量和二硫键含量与分离蛋白凝胶强度的相关性系数分别是0.9473和-0.9231。表面疏水性和分离蛋白凝胶强度的相关性系数是0.7500。接着研究新制豆粕在不同贮存温度下,贮存时间对其氧化特征的影响。随着贮存时间的延长,豆粕TBA值和羰基含量逐步增大;巯基含量是先增大后逐步减小,二硫键含量则相反;表面疏水性变化也是先增大后减小。豆粕各氧化指标与提取的分离蛋白凝胶强度相关性分析表明:TBA值和羰基含量也与分离蛋白凝胶强度没有相关性。巯基含量和二硫键含量与分离蛋白凝胶强度的相关性系数分别是0.9260和-0.9270。表面疏水性和分离蛋白凝胶强度的相关性系数分别是0.9339,比加热豆粕的相关性大大提高了。最后研究了不同因素对脂肪氧合酶同工酶活力的影响。为了保存脂肪氧合酶的活力,本文以自制低变性脱脂豆粕为研究对象,分别研究干热处理、pH、金属离子、酸根离子、金属络合剂以及抗氧化剂对脂肪氧合酶同工酶活力的影响。结果表明只有干热处理才能彻底钝化酶活。由以上可知,脂肪氧合酶可促进脱脂豆粕氧化;其氧化指标巯基和二硫键含量与分离蛋白凝胶强度具有明显的相关性,而表面疏水性和分离蛋白凝胶强度也有着较好的相关性。更多还原

【Abstract】 Effects of oxidation induced by lipoxygenase (Lox) in defatted soybean flour on gelling properties of the corresponded soybean protein isolates (SPI) were discussed in this paper. The relationship between markers of oxidized defatted soybean flour and gelling properties of the corresponded SPI was analyzed in order to seek a rapid and simple method to evaluate the gelling properties of SPI from its raw material.Firstly, heating temperature, heating time and water content, three important factors of dry heating, were controlled to get defatted soybean flour containing a series of different activity of Lox. Effects of different activity of Lox on TBA value, carbonyl content, sulfhydryl and disulfide content and surface hydrophobicity of defatted soybean flour were compared.At the same time,SPI was extracted by alkali extraction and the texture of gelling properties was researched.Through the relativity analysis we could get: the correlative coefficient between the gelling intensity and TBA value and carbonyl content were almost zero,the correlative coefficient between the gelling intensity and sulfhydryl content and disulfide bonds content of soybean protein were 0.9473 and -0.9231,respectively,while the correlative coefficient between between the gelling intensity and surface hydrophobicity of of soybean protein was 0.7500.Effect of conservation conditions of defatted soybean flour on the oxidation and gelling properties of SPI were also studied. New-made defatted soybean flour was stored different temperature, as conservation time increased, TBA value and the carbonyl content of defatted soybean flour increased;the sulfhydryl content showed a trend that increased first and decreased after;at the same conditions,the change of disulfide bonds was contrary with the sulfhydryl content;the surface hydrophobicity also showed a trend that rose first to behind after.The relativity analysis was showed that:there were no relativity between the gelling intensity and TBA value and carbonyl content; the correlative coefficient between the gelling intensity and sulfhydryl contentand disulfide bonds content of soybean protein were 0.9260,-0.9270,respectively,while the correlative coefficient between between the gelling intensity and surface hydrophobicity of of soybean protein was 0.9339.Lastly,effects of different factors on the activity of Lox were studied. Low denatured defatted soybean flour which prepared by laboratory was used as material in order to obtain high Lox activity of defatted soybean flour. Effect of dry heating, pH, metal ions, acid radical ions, metallic complexes and antioxidants on the activity of Lox isozyme was compared.The result was that activity of Lox isozyme could be completely inactivated only by drying heat.Based on the obtained facts, we can found that lipoxygenase could promote oxidation of defatted soybean flour. The contents of sulfhydryl and disulfide bonds of defatted soybean flour show significant relativity with gelation strength of SPI, and surface hydrophobicity of defatted soybean flour also shows a good relativity with gelation strength of SPI.更多还原