豆浆中抗营养因子的去除方法

采用碱液浸泡、微波处理、加热处理、去皮等方法,对去除豆浆中抗营养因子的效果进行比较。其中,88℃恒温热处理10min可将豆浆中脂肪氧化酶活性降至常温下的14.20%,100℃恒温热处理20min可将豆浆中的胰蛋白酶抑制剂降低到9.96%。微波处理(2450MHz,800W)2min可以将脂肪氧化酶活性降至8.86%,处理8min可以将胰蛋白酶抑制剂活性降低到11.24%,处理4min即可将尿素酶活性降低至1%。相比于常规的热处理,微波处理可以更快速地破坏豆浆中的抗营养因子,缩短处理时间。此外,采用0.5%NaHCO3溶液浸泡、去皮等措施也可去除豆浆中的抗营养因子,可结合常规热处理、微波处理应用,以缩短加工时间。      

大豆蛋白质纤维及其产品性能

主要介绍了大豆蛋白质纤维的特征性能以及开发新产品的特点及意义。     

蚕蛹蛋白挥发性成分分析及体外消化特性研究

本文以碱溶酸沉提取的蚕蛹蛋白为原材料,采用GC-MS比较了烘干与冻干两种蚕蛹蛋白挥发性成分,同时研究了热处理温度及时间,不同处理方式对蚕蛹蛋白体外消化率的影响。试验结果表明:从烘干蚕蛹蛋白和冻干蚕蛹蛋白中分别鉴定出26种和35种挥发性化合物,蚕蛹蛋白中挥发性物质主要为醛类化合物,而其臭味主要来源于醇类化合物和硫化物,且含量较少,亦与部分醛类化合物有关;热处理可显著提高蚕蛹蛋白体外消化率(p0.05),不同处理方式下蚕蛹蛋白体外消化率高低依次为辐照(10 k Gy)蒸煮(100℃,1 h)微波(700 W,3 min)蒸煮(100℃,20 min)干热(130℃,1 h)未处理,热处理60 min后,蚕蛹蛋白胰蛋白酶抑制因子活性值(TIA)仅为14.52%,胰蛋白酶被抑制百分比下降到38.37%。     

Changes in lipoxygenase isozymes and trypsin inhibitor activity in soybean during germination at different temperatures

Influence of germination temperature on lipoxygenase isozymes and trypsin inhibitor activity, the two undesirable components in soybean for human consumption, is not yet reported in soybean sprouts. Two Indian soybean genotypes were incubated for 144 h in a seed germinator at two different temperatures (25 and 35 °C) and the activities of lipoxygenase isozymes and trypsin inhibitor were monitored in the germinating seedlings every 24 h. Lipoxygenase-I as well as lipoxygenase-II + III were degraded continuously over the 144 h and the rate of degradation, of both the classes of lipoxygenase, was faster at the higher germinating temperature (35 °C) in both the genotypes. Trypsin inhibitor was also degraded continuously during germination upto 144 h and the degradation was faster at higher germination temperature. Protein extracts of seedlings of different periods, developed at different temperatures, and analyzed using polyacrylamide gel electrophoresis, indicated that the original Kunitz inhibitor band (R_f = 0.75) declined continuously in intensity during germination at both temperatures in both genotypes, and a new band (R_f = 0.72) possessing trypsin inhibitor activity appeared at 48 h at 35 °C, while it appeared at 72 h at 25 °C. Early appearance of a modified form of Kunitz inhibitor, a degraded product of native form, at 35 °C as compared to 25 °C, confirms that the faster quantitative reduction at higher temperature is due to faster degradation of the original Kunitz inhibitor form at higher temperature.     

Heat Inactivation Kinetics of Trypsin Inhibitors During High Temperature-Short Time Processing of Soymilk

Heat treatment of soymilk was studied in the conventional batch boiling process and under High Temperature-Short Time (HTST) conditions. Reduction in total trypsin inhibitor was assayed enzymatically, and individual inhibitors, the Kunitz and the Bowman-Birk inhibitor, were assayed by ELISA technique. Standard first-order reaction kinetics and thermodynamics were applicable for inactivation, and results indicated that the mechanism was not protein unfolding, because entropy changes were zero or negative. The two inhibitors were inactivated at the same rate around 137°C. Therefore, a simple first-order kinetic model which gave a good, slightly conservative estimate of residual anti-trypsin activity under HTST conditions could be established.     

淡水鱼肉蛋白质组成及其在鱼糜制品加工中的变化

本文通过鱼肉蛋白质组成、鱼糜凝胶特性的测定及SDS-PAGE凝胶电泳,研究了鲢、鳙、草、鲫四种淡水鱼鱼糜凝胶特性及其凝胶形成过程中蛋白质组成的变化。四种淡水鱼肉粗蛋白质含量基本相同,但凝胶特性存在明显差异,其原因是四种淡水鱼肉的盐溶性蛋白含量不同。在鱼糜制品加工过程中,盐溶性蛋白质、水溶性蛋白的比例逐渐下降,而不溶性蛋白比例逐渐上升。弹性凝胶体的形成始于盐擂阶段,主要形成于低温凝胶化阶段。SDS-PAGE凝胶电泳图谱显示,肌球蛋白重链的量在鱼糜凝胶形成过程中明显减少,而肌球蛋白轻链和肌动蛋白的量几乎未发生变化。肌球蛋白重链在内源转谷氨酰胺酶作用下,发生分子间或分子内的ε-(γ-Glu)-Lys共价交联,形成了网络状的不溶性蛋白。     

Characterization of proteins from kernel of different soybean varieties

BACKGROUND: Total soybean proteins, storage proteins, glycinin (11S) and β‐conglycinin (7S) fractions and their respective subunits in seven soybean varieties were analyzed. In this work we also present the correlation between concentration and activity of bioactive proteins, lipoxygenase and proteinase inhibitors. RESULTS: Glycinin and β‐conglycinin comprise about 750 g kg^?1 of the bean storage protein and as such account for both quantity and quality of the kernel protein. The 11S concentration of the varieties studied ranged from 503.4 to 602.9 g kg^?1 and those of 7S varied from 178.2 to 230.6 g kg^?1 of total extractable proteins. The ratio of 11S/7S proteins varied from 2.43 to 3.29 among the varieties. A very strong positive correlation was found between the concentration of Kunitz trypsin inhibitor and activity of total trypsin inhibitor (r = 0.96). However, lipoxygenase concentration did not show a strong correlation with lipoxygenase activity. CONCLUSION: It appears that among the seven ZP soybean genotypes there are genotypes with different amounts of subunits that should be bred in the future for a desired level of protein components. Copyright © 2010 Society of Chemical Industry     

Effects of Water,Steam and Shear Conditioning on the Protein Quality of Soy Grits

The effect of adding steam (at 0·6 and 1·2 bar) and water (1·9% and 64% of the flux of soy grits) in a conventional barrel type conditioner and its effects on protein dispersibility index (PDI), nitrogen solubility in 0·2% KOH and trypsin inhibitor activity (TIA) of commercial soy grits was studied. In addition, conditioned soy grits were subjected to expander treatment at two different screw speeds (2 and 3 rps) and PDI, NSI and TIA were measured. Analysis of variance was used to determine the effects of steam pressure, water addition and screw speed on the mentioned protein quality parameters. In addition, resultant temperature from steam addition was used in an analysis of covariance to determine the effects of temperature as a covariate, water addition and screw speed on protein quality parameters. A significant interaction for steam pressure and water addition was found on all parameters. The highest denaturation or inactivation of the protein was found at the combination incorporating high steam and high water addition. Screw speed during expander treatment did not significantly affect protein quality parameters. It was concluded both from this study and from literature that PDI is a better parameter to evaluate technological treatments when low amounts of motor power are dissipated (<110 kJ kg^-1) and that NSI in 0·2% KOH is a better parameter to discriminate between technological treatments when moderate to high amounts of motor power are dissipated in soy grits. TIA decreased with increasing water or steam content. The effect of trypsine inhibitor inactivation in soy grits was highest at higher temperatures and was not affected by screw speed of the expander. © 1997 SCI     

STI的抑制作用及茶多酚作用下STI的失活探讨

大豆中的两种主要的胰蛋白酶抑制剂对胰蛋白酶的活性有很强的抑制作用,随着胰蛋白酶抑制剂的增加,胰蛋白酶活性几科能完全被抑制;茶多酚能有效地和胰蛋白酶抑制剂络合而使抑制剂对胰蛋白酶的抑制作用减弱,同时研究表明茶多酚络合失活胰蛋白酶抑制剂还受温度的影响。     

Alcalase蛋白酶降解大豆胰蛋白酶抑制剂的研究

研究了不同酶解条件下 (pH值、温度、时间、加酶量和添加巯基还原剂 ) ,碱性内切蛋白酶Alcalase对大豆蛋白和大豆胰蛋白酶抑制剂的降解作用。研究结果表明 ,Alcalase可同时降解大豆蛋白和胰蛋白酶抑制剂。该酶解反应的最适条件为 :pH 8 0、温度 6 0℃、最适加酶量 10 μL/g蛋白 (约 0 0 2 832AU/ g蛋白 ) ,添加Na2 SO3为ω(Na2 SO3) =0 3% ,水解时间 4h。在此条件下 ,残留胰蛋白酶抑制活性为对照的 2 0 % ,可溶性蛋白含量可达 2 7mg/mL ,游离氨基酸含量为 7 1mg/mL ,大豆蛋白的水解度为 8 9%。还讨论了Alcalase蛋白酶降解大豆蛋白生成小肽的最佳反应条件     

赤灵芝中三萜类活性成分的提取筛选和质谱分析

研究赤灵芝总三萜最佳提取工艺条件,评价三萜类化合物对脂肪氧化酶的抑制效果。采取单因素实验和响应面法分析提取时间、提取次数、液料比和乙醇浓度对赤灵芝三萜得率的影响,筛选最佳工艺参数;利用高效液相色谱-电喷雾质谱联用技术（HPLC-ESI-MS）对赤灵芝中三萜类提取物化学成分进行分析鉴定,以脂肪氧化酶为生物靶分子,采用超滤质谱技术筛选酶抑制剂,探究三萜类化合物对脂肪氧化酶的抑制效果。结果显示：最佳工艺条件为料液比1:30、乙醇浓度75%、提取次数3次和提取时间1.5 h;在这些条件下,总三萜得率为1.04%;从赤灵芝中筛选出5种脂肪氧化酶抑制剂,5种化合物对1.0 U/mL脂肪氧化酶活性有较强抑制作用,抑制效果的强弱顺序为灵芝酸B（52.64%）>灵芝酸C2（40.21%）>灵芝酸D2（31.25%）>灵芝酸F（12.69%）>灵芝酸A（10.82%）。实验结果表明,响应面法筛选赤灵芝三萜的提取工艺参数准确可靠,可用以赤灵芝三萜的生产制备;赤灵芝中三萜类活性成分可抑制脂肪氧化酶,表明有缓解炎症的功效,研究结果可为赤灵芝中抗炎成分的进一步研究提供一定理论基础。     

面团加工过程中蛋白质含量的变化

以3种不同品质性状的小麦为原料(分为3类,即3个等级),研究了小麦粉面团在搅拌过程中清球蛋白、醇溶蛋白和麦谷蛋白含量的变化。结果表明:蛋白质含量在面团搅拌过程中发生了有规律的变化,这种变化与面团特性及面团加工品质间有较密切关系。     

Trypsin inhibitor activity of soybean as affected by genotype and fertilisation

The presence of protease inhibitors in soybean prohibits the utilisation of the raw beans for food and feed. However, little information is available about environmental influences and the effects of nitrogen and sulphur supply on the antinutritional constituents of soybean. As these factors may influence protease inhibitors, soybean genotypes segregated according to the presence or absence of the Kunitz trypsin inhibitor have been evaluated for trypsin inhibitor activity (TIA) in field trials. TIA was affected significantly by environment (geographical location), fertilisation treatment and genotype. Environmental means of TIA were between 69.5 and 104.8 mg g^?1. Nitrogen application, which caused an increase in seed protein content, resulted in a reduction in TIA by about 15% as compared with the control. Remarkably, simultaneous application of nitrogen and sulphur in the form of ammonium sulphate had a similar reductive effect on TIA to that of nitrogen application alone, although soybean protease inhibitors are rich in sulphur amino acids. Significant genetic variation in TIA was found both within the genotype class with the Kunitz inhibitor present as well as within the class lacking this inhibitor. The results suggest that TIA of soybean may be modified considerably by genetic improvement and appropriate agronomic management. Copyright © 2003 Society of Chemical Industry     

Effect of Water Activity on Lipid Oxidation and Protein Solubility in Freeze-dried Beef during Storage

ABSTRACT: Ground beef patties (15% fat) were freeze-dried to different a_w endpoints and stored at 25°C or 49°C. Water activity, total moisture (%), lipid oxidation (TBARS@450nm), and protein solubility were evaluated. TBARS @450nm was favored at 49°C, but not at 25°C except at high a_w range (p < 0.05), whereas protein solubility was greater at 25°C than 49°C (p < 0.05). TBARS@450nm values at 49°C were generally greatest at low a_w range (p > 0.05). Protein solubility was lowest at medium a_w at 49°C (p < 0.05), while at 25°C low a_w protected protein solubility better than other low or high a_w values.     

乳清浓缩蛋白对松仁蛋白溶解度及其乳液稳定性的影响

为研究蛋白质-蛋白质相互作用对松仁蛋白(PKP)溶解度、结构和乳液性质的影响,以PKP和乳清浓缩蛋白(WPC)为研究对象,采用pH循环法制备PKP-WPC复合蛋白,利用SDS-PAGE、内源性荧光光谱、紫外-可见光谱、圆二色谱、荧光探针和ζ-电位等方法分析了复合蛋白结构特性和表面特性,再以PKP-WPC复合蛋白为原料,分别制备了油相体积分数为3%、10%和50%的乳液,并对制备的乳液性质进行了检测。结果表明:当WPC与PKP的质量比为1.0∶1.0,且体系pH值经历由7.0到12.0再回到7.0时的1次pH循环后,PKP的水溶性可从48.53%提高到92.43%。SDS-PAGE结果显示,PKP-WPC复合蛋白完整保留了PKP和WPC的亚基。内源性荧光光谱、紫外-可见光谱和圆二色谱结果表明,静电相互作用、疏水相互作用和氢键是驱动PKP和WPC相互作用的主要作用力,PKP与WPC相互作用使复合蛋白具有较高的结构韧性,抵抗酸诱导的构象折叠;WPC的加入改变了PKP的二级结构,α-螺旋、β-转角和无规卷曲结构的含量增加,而β-折叠结构相对含量降低。PKP-WPC复合蛋白具有较高的表面电荷(-34.74mV)来抵抗蛋白质的聚集。与由PKP制备的乳液相比,由PKP-WPC制备的乳液平均粒径和乳层析指数减小,ζ-电位绝对值增大,稳定性显著提高。乳液的性质因油相体积分数的不同而有较大的差异。油相体积分数为3%的复合乳液液滴小且分布均匀,稳定性好于油相体积分数为10%和50%的复合乳液。通过pH循环法,通过添加WPC,提高了PKP的溶解度,获得了稳定性较佳的PKP乳液,研究可为新型蛋白产品的研发提供理论基础,拓宽松仁蛋白在加工食品中的应用范围,推动PKP-WPC双蛋白乳液研究的发展。     

Effects of NaCl Concentration on Salting-in and Dilution During Salting-out on Soy Protein Fractionation

ABSTRACT:  Glycinin and β-conglycinin are the main storage proteins in soybeans that can be fractionated by using alkali extraction, SO₂, salting-in with NaCl, salting-out by dilution and pH adjustment to produce a glycinin-rich fraction, a β-conglycinin–rich fraction, and an intermediate fraction, which is a mixture of the two proteins. Two different strategies were employed to optimize the procedure to achieve high efficiency in recovering the β-conglycinin–rich fraction. The first strategy was to optimize salting-in effects of NaCl, and the effects of NaCl concentration on the yields and purities of the protein fractions were investigated. The maximum protein yield of the β-conglycinin–rich fraction was obtained at 500 mM NaCl, but at the expense of purity. The optimum NaCl concentration was 250 mM, at which good protein yield (18.5%) and purity (84.5%) were achieved. At higher NaCl concentrations, the protein yields of the intermediate fractions were significantly lower, and the protein loss in the whey fraction increased. The second strategy was to improve the salting-out step for the β-conglycinin–rich fraction. At 0- and 0.5-fold dilution, the purities and yields of the β-conglycinin–rich fractions were significantly lower than at 1.0- and 2.0-fold dilution. There were no differences in protein yields or purities when using 1.0- or 2.0-fold dilution. According to these results, the recommended NaCl concentration for the salting-in step is 250 mM and the dilution factor for salting-out is 1.0.     

茶叶籽粕蛋白功能特性研究

以大豆分离蛋白为对照,研究碱法和酶法提取茶叶籽粕蛋白的功能特性。结果表明：酶法提取茶叶籽粕蛋白的溶解性、吸油性、乳化能力和乳化稳定性、起泡性、凝胶脆度优于碱法提取茶叶籽粕蛋白,而后者的吸水性、泡沫稳定性则优于前者,两者所形成蛋白凝胶的黏性和硬度相当。碱法和酶法提取的茶叶籽粕蛋白的乳化能力和乳化稳定性稍优于大豆分离蛋白,但起泡性和泡沫稳定性则不及大豆分离蛋白,溶解性与大豆分离蛋白相当,它们形成凝胶的最低质量分数分别为13%和15%,凝胶的黏性和硬度低于大豆分离蛋白。pH值、蛋白质量分数、NaCl浓度等因素对茶叶籽粕蛋白功能特性均有不同程度的影响。     

酰化大米蛋白理化性质及胰蛋白酶酶解性质研究

对酰化大米蛋白的溶解度、表面电荷情况及二级结构等理化特性进行初步探讨,同时研究了酰化大米蛋白胰蛋白酶酶解特性。结果表明,大米蛋白等电点随着酰化程度的增大,越来越向酸性方向迁移,由原来的4.8分别迁移到4.4、3.8、3.3。酰化能够改善大米蛋白的溶解性,从0.4 mg/m L提高到了0.7 mg/m L(中性p H)。酰化能够明显增加蛋白质表面的净负电荷,酰化程度越大,净负电荷增加越多。酰化对大米蛋白的二级结构也有一定的影响,α-螺旋和无规卷曲含量基本不变,β-折叠含量下降,β-转角的含量上升。酰化可以提高大米蛋白胰蛋白酶酶解速率和消化率,相同底物浓度时动力学参数a随着酰化度的增大而增大。酶解物电泳表明,胰蛋白酶酶解120 min后,未改性大米蛋白酶解物在20 k Da、16.9 k Da和14 k Da处仍有清晰可见的条带,改性大米蛋白酶解物则这些条带几乎都完全消失。