大豆分离蛋白与麦芽糊精的Maillard反应性及产物乳化性质研究

以SDS-聚丙烯酰胺凝胶电泳和毛细管电泳研究了大豆分离蛋白-麦芽糊精的Maillard反应形成的共聚物。电泳分析表明:7S亚基与麦芽糊精的反应性较高,而且在文中所研究的蛋白质与多糖质量比的范围内,7S亚基都能与麦芽糊精发生定量的共聚合反应,形成分子特性高度一致的共聚物;而11S亚基与麦芽糊精间的反应性较低,共聚物的分子特性受蛋白质与多糖质量比的影响。共聚物在pH7.0和pH4.5时的乳化性能优于酪朊酸钠,尤其是在pH4.5时具有优良的乳化稳定性。但在较高NaCl浓度时的乳化活性与大豆分离蛋白相比没有明显的改善,其乳化稳定性则明显优于酪朊酸钠。     

大豆蛋白-瓜尔豆胶水解物Maillard反应共聚物的乳化特性研究

研究了不同水解时间的瓜尔豆胶对蛋白质-多糖Maillard反应共聚物的乳化特性的影响及不同水相条件下共聚物与酪朊酸钠乳化特性的差异。研究表明,瓜尔豆胶的酸水解时间对大豆分离蛋白-多糖共聚物的乳化活性和乳化稳定性都有明显的影响。水解40min的瓜尔豆胶与大豆分离蛋白反应10 d的共聚物具有优良的乳化性能;在0.3mol/L NaCl和pH 4.0的酸性条件下,共聚物的乳化活性和乳化稳定性都明显高于商品乳化剂酪朊酸钠;在90℃热处理60 min后其乳化活性和乳化稳定性仍接近未经热处理时的酪朊酸钠的乳化活性和稳定性。该共聚物作为安全高效的天然高分子食品乳化剂具有广阔的应用前景。     

大豆蛋白水解产物中巯基的热稳定性和抗氧化作用的研究

研究了大豆蛋白水解产物中巯基的热稳定性及抗氧化作用。结果表明,SPI水解不影响巯基含量;加热时大豆蛋白溶液中巯基含量下降近52%,而大豆蛋白水解产物中巯基的含量只下降4%,说明大豆蛋白水解产物中巯基的热稳定性明显提高。当巯基被封闭时,大豆蛋白水解产物的抗氧化性明显减弱,说明巯基是大豆蛋白中很重要的抗氧化成分,但较其他一些抗氧化基团更易于氧化。     

Gel-forming Ability and Radical-scavenging Activity of Soy Protein Hydrolysate Treated with Transglutaminase

ABSTRACT: Gel-forming ability and 1,1-diphenyl-2-picrydrazyl (DPPH) radical-scavenging activity of the peptic hydrolysate from soy protein isolate (SPI) were investigated. The gel-forming ability of mixtures consisted of SPI and its hydrolysate decreased as the percentage of hydrolysate increased. The inferior gel-forming ability of the hydrolysate was shown to be related to both the low surface hydrophobicity of the hydrolysate and the drop in sulfhydryl exchange reactions during gelation. Although antioxidants in the SPI-hydrolysate mixture (SHM) could be helpful in enhancing the radical-scavenging activity of the peptide-based gel, they suppressed the oxidization of sulfhydryls in sulfhydryl group/disulfide bond interaction. As a result of this, antioxidants present reduced the gel-forming ability of the SHM. The addition of transglutaminase (TGase) improved the gel-forming ability of SHM. A mixture of 70% SPI and 30% hydrolysate in the presence of TGase resulted in a gel with good gelling property and high radical-scavenging activity.     

大豆蛋白酶解物的功能特性研究

就脱脂豆粕酶解物在不同环境条件下的溶解性、粘度、吸水性、吸油性、起泡性与泡沫稳定性、乳化性与乳化稳定性进行了研究 ,并就几种因素对大豆蛋白酶解物的功能特性的影响进行了讨论 ,为大豆蛋白酶解物的广泛应用提供了理论依据     

复合改性改善大豆分离蛋白功能性质的研究

为考察糖基化接枝及酶法相结合的复合改性对于大豆分离蛋白功能性质的影响,以提高接枝度及产物乳化能力等功能性质为主要指标,制备大豆分离蛋白与麦芽糊精糖基化产物,随后采用中性蛋白酶对该产物适度酶解,得到不同水解程度的糖基化产物水解物,研究产物的乳化能力、起泡性能及抗氧化能力的变化。实验结果表明:经过接枝及适度酶解复合改性后,大豆分离蛋白的乳化能力、起泡性能及DPPH自由基清除能力均有了较大的提高,但深度的酶解有可能破坏蛋白的空间结构,降低粘度从而影响功能性质的发挥。     

大豆分离蛋白乳化性的研究

采用蛋白质乳化容量电导法,对不同浓度、ＰＨ和酶水解条件下大豆分离蛋白乳化容量和乳化稳定性进行测定,结果表明：大豆蛋白的乳化性在低密度时随浓度上升而增加,浓度达到６％以后趋于稳定;等电点时（ＰＨ４．５）,乳化性最差,偏离等电点后尤其在偏碱性条件下,乳化性明显增加,酶水解后,乳化性变化产大,水解度１７％时,乳化性最佳。     

Solubility and Emulsifying Properties of Soy Protein Isolates Modified by Pancreatin

Soy protein isolates (SPI) with varying degrees of hydrolysis (DH of 7, 11, 15, 17%) were produced using pancreatin. The surface hydrophobicity indices of pancreatin hydrolyzed SPI (PSPI) (34.5, 34.9, 39. 1, and 40.7 for 7, 11, 15, 17% DH, respectively) were higher than that of SPI (10.5) and control SPI (CSPI) (12.5, 11.9, 12.9, and 12.6 for 10, 60, 120, and 180 min incubation, respectively). The solubilities of PSPI at pH 4.5 were 2.7, 9.1, 11.9, and 18.7%, for 7, 11, 15, and 17% DH, respectively, while the solubilities of SPI and CSPI at the same pH were about 1. 6%. Solubilities of PSPI at pH 7. 0 were > 90% for all DHs tested, while those of SPI and CSPI were 85%. The emulsifying activity index (EAI) of PSPI increased with increasing DH. PSPI with 15% DH had highest EAI (1. 122) which was higher (P < 0. 05) than those of SPI (0.550) and CSPI after 120 min incubation without enzyme (0.568). These results suggest that PSPI could be used as an ingredient for emulsified products and where high solubility at low pH is required.     

改性大豆蛋白的凝胶流变性

研究了大豆蛋白水解物的凝胶流变学特性。研究结果表明,在pH7.6和pH5.2时,与大豆蛋白相比,大豆蛋白水解物的凝胶化温度升高、凝胶化时间延长;但凝胶的储能模量降低了。     

超滤对罗非鱼下脚料蛋白酶解物功能特性的影响

以罗非鱼下脚料为原料,采用pH-stat法控制酶解,滤膜对罗非鱼下脚料胰蛋白酶水解产物（DH5．0％）进行超滤。1-2倍,乳化稳定性提高1．1倍;发池陛略有提高。制备5．0％的罗非鱼下脚料酶解蛋白。采用截留分子量为5kDa的超结果显示：蛋白回收率为89．21％,脱盐率为87．59％,乳化活性提高     

超声及干热美拉德反应对大豆分离蛋白功能特性的影响

大豆分离蛋白(SPI)是一种十分重要的植物蛋白,工业化生产会导致SPI变性,但是目前改性对SPI功能特性的影响还缺乏系统的研究,因此通过分析超声波处理及干热美拉德反应改性方法对SPI溶解性、内源性荧光、表面疏水性、乳化性及乳化稳定性、发泡性及发泡稳定性的影响,为不同改性方法研发SPI产品提供参考.结果 发现,超声波处理...     

Soy Protein Hydrolysate Debittering by Lysine-Acetylation

To reduce bitterness of soy protein hydrolyates, chemical modification of lysine was investigated. Isolated soy protein (ISP) was treated with N-acetylimidazole for acetylation of lysine and tyrosine. 0-acetyI tyrosine was deacetylated at pH 11. The lysine-acetylated soy protein and control protein were hydrolyzed by bromelain to the same degree of hydrolysis (10%), and then bitterness of each protein hydrolysate was evaluated. Sensory analyses indicated that bitterness of hydrolysates of lysine-acetylated ISP decreased in comparison with hydrolysates of control ISP (p<0.005). Surface hydrophobicity of hydrolysates of lysine-acetylated ISP slightly increased, and they had fewer lysine residues at the C-terminal region than hydrolysates of control ISP.     

Xanthan Gum Effects on Solubility and Emulsification Properties of Soy Protein Isolate

The effect of xanthan gum (XG) on solubility and emulsifying properties of soy protein isolate (SPI) was evaluated. The solubility of SPI was increased by addition of XG (p < 0.05). The emulsifying activity of SPI-XG was 4 times higher than that of SPI or XG alone (p < 0.05) and similar to that of bovine serum albumin (BSA) (P > 0.05). The emulsifying stability of SPI-XG dispersions was respectively 3 and 2 times higher than that of SPI and BSA (p < 0.05). The solubility and emulsifying properties of SPI-XG dispersions were stable over a wide range of pH (3.0 to 9.0), ionic strength (0.1 to 1.0M NaCl), and heat (85°C, 1 hr).     

Characterization of Soy Protein Concentrate Produced by Membrane Ultrafiltration

The functionality of membrane processed soy concentrate was very similar to soy flour in terms of solubility and water hydration capacity. The high emulsifying activity index of soy flour is believed to be reflective of its higher solubility, while surface hydrophobicity is believed to be responsible for an equally high emulsifying activity index in acid precipitated soy isolate. The proteins of soy flour and membrane soy concentrate seem to have most of their hydrophobic residues buried in the interior, while they are exposed in acid precipitated soy isolate. Heating resulted in a decrease in solubility but improved the hydration capacity and emulsifying activity of both soy flour and membrane soy concentrate. The essential amino acid profile of concentrate was comparable to current commercial isolates manufactured by acid precipitation. The majority of the polypeptides present in soy flour were observed to be present in the concentrate. The membrane soy concentrate was determined to have the least soybean aroma when compared to both soy flour and acid precipitated soy isolate.     

低温冷冻条件对大豆分离蛋白功能性的影响

通过大豆分离蛋白（soybean protein isolate,SPI）冷冻前后功能性的变化,研究低温冷冻条件（料液比、冷冻温度、冷冻时间）对SPI功能性（保水保油性、乳化特性及质构特性）的影响。结果表明：在经过冷冻实验的样品中,随着SPI添加量的减小,其保水保油性、乳化性先增加后减小,当SPI料液比为1∶12时,其保水性、保油性、乳化稳定性、硬度和弹性均达到相对最大;冷冻温度为－18 ℃时,其保水保油性、乳化性、硬度和弹性相对最大,－20 ℃时,其乳化稳定性相对最好;随着冷冻时间延长,其乳化稳定性减小,冷冻3 d时,SPI的乳化稳定性相对最好,冷冻2 d时其保水性相对最大。和未经冷冻处理的原样品相比,经过冷冻处理的SPI,功能性明显减弱,其中保水保油性、乳化性、质构特性都小于未冷冻处理的SPI。     

天然和热处理大豆蛋白稳定乳液的性质研究

热处理(901、20℃)修饰的大豆分离蛋白用于制备水包油(O/W)乳液,并对天然和热处理蛋白乳液的粒径、微结构、絮凝率和分层稳定性进行表征。热处理蛋白的水力学半径随蛋白浓度和加热温度的增加而增加,证实了可溶性聚集体的产生。乳液粒径和分层稳定性受离子强度、聚集体粒径影响。低离子强度下(0 mmol/L),与天然蛋白相比,热处理蛋白乳液粒径较大,20 d放置后未发生分层。离子强度的增加(100mmol/L)导致天然蛋白乳液粒径明显增大;而热处理蛋白乳液则表现出较高耐盐性,体现在更小的粒径、絮凝率和分层指数。与90℃热处理相比1,20℃热处理减小了乳液液滴的粒径和絮凝。     

酶解大豆分离蛋白乳化特性的研究

利用枯草芽孢杆菌AS1．398中性蛋白酶对大豆分离蛋白进行水解，并利用浊度法测定了不同水解度、不同pH条件下酶解大豆分离蛋白的乳化特性，结果表明：AS1．398蛋白酶对大豆分离蛋白的最大水解度为36％，水解度为9％时乳化活性最大，水解度为3％是乳化稳定性最好。同一水解度时，pH越高，蛋白质的乳化特性越好。水解度为3％、9％、15％的大豆分离蛋白在pH等于或高于5．0时的乳化活性明显地高于原蛋白质，且水解度为3％时乳化稳定性也明显地高于原蛋白质。     

酶解产物浓度和油相体积分数对甘薯蛋白酶解产物乳化特性的影响

本文研究了酶解产物浓度(0.10%、0.25%、0.50%、0.75%和1.00%,m/V)和油相体积分数(5%、15%、25%、35%和45%,V/V)对超高压下酶解制得甘薯蛋白酶解产物乳化液显微结构、乳化颗粒平均粒径(d4,3)、乳化活性指数(EAI)、乳化稳定性指数(ESI)和流变学性质的影响。当酶解产物浓度较低和油相体积分数较高时,乳化液的乳化颗粒均一细小。增加甘薯蛋白酶解产物浓度会使其乳化液的d4,3、EAI和ESI均逐渐降低;相反,增加油相体积分数会使乳化液的d4,3逐渐减小,EAI逐渐增大,而ESI则先降低后增加(p0.05)。在酶解产物浓度低和油相体积分数高时,乳化液的初始表观粘度较大,且在1~100 s-1的剪切速率范围内均表现出了剪切变稀现象。酶解产物浓度和油相体积分数与乳化液的d4,3、EAI、ESI和流变学性质密切相关,是影响甘薯蛋白酶解产物乳化特性的重要因素。     

Protamex蛋白酶水解大豆蛋白研究

研究了Protamex酶对大豆蛋白的有限水解作用 ,分析了酶浓度、pH值、温度、底物浓度、反应时间等因素对大豆蛋白酶水解的影响 ,给出了Protamex酶水解大豆蛋白的较佳条件 ,并采用凝胶层析过滤色谱分析了不同水解时间水解物分子量的变化 ,发现大豆分离蛋白中存在一些Pro tamex不容易水解成分 ,大豆分离蛋白的Protamex水解过程是一个不均匀的过程。