大米蛋白乳化性质研究

本文研究了大米分离蛋白(RPI)、酶法大米分离蛋白(E-RPI)、谷蛋白等在不同pH和Na2SO3存在条件下的乳化性能及其表现特点，并与大豆分离蛋白(SPI)的乳化性能进行了比较，结果表明，增加大米蛋白溶解性的措施均有利于改善大米蛋白的乳化性能。谷蛋白一旦溶解其乳化能力与大豆蛋白相当。RPI、E-RPI经Na2SO3处理后，乳化性能明显提高，说明通过解除大米蛋白分子中亚基的聚合，可以改善大米蛋白的物化功能性。     

大豆分离蛋白提升鲜湿米粉凝胶品质的研究

为探究大豆分离蛋白(Soy Protein Isolate, SPI)对鲜湿米粉凝胶品质的影响,将SPI以0%、2%、4%质量浓度比例与发酵籼米粉混合,对SPI-发酵籼米混合粉的性质及所制SPI-鲜湿米粉的凝胶品质进行测定,并分析了SPI-鲜湿米粉内部淀粉结构的变化。结果表明：随着SPI添加量的增加,SPI-发酵籼米混合粉的糊化黏度增大,崩解值减小,凝胶硬度增大,推断SPI的添加有利于发酵籼米淀粉的凝胶化;进一步测定发现,SPI-鲜湿米粉的硬度、咀嚼性、胶黏性增大,蒸煮吸水率上升,说明添加SPI可提升鲜湿米粉凝胶品质;FT-IR显示,R104 7/102 2 cm-1峰强度比值增大、R102 2/995 cm-1峰强度比值减小,两者比值表示鲜湿米粉内部淀粉短程有序结构和氢键强度增加,即淀粉短程有序性升高,这可能与鲜湿米粉凝胶品质的提升相关。     

Cadmium Removal from Rice by Separating and Washing Protein Isolate

In this study detoxification of 3 Chinese Cd‐contaminated cultivars (Jinyou463, Yuchi, and Xiangzaoxian 32) of rice was explored. By separation with an alkaline method, Cd concentrations of the starch isolates were decreased from 0.2769, 0.4037, and 0.5156 mg/kg in starting milled rice to 0.1056, 0.1585, and 0.1923 mg/kg, respectively. However, the Cd concentrations reached up to 2.5905, 3.1628, and 4.8593 mg/kg in the protein isolates, respectively. Therefore, 10 common acids in food industry were investigated to remove Cd from protein isolate by washing process. The optimal washing conditions were 0.5 M citric acid, acid to rice protein isolate ratio of 6:1 v/w, shaking time of 1 h at room temperature. The rice protein isolate showed a significant decrease in Cd concentration and the removal efficiency was more than 95% after 2 washings at optimized conditions. Rice proteins were not degraded at all and had very little loss during citric acid washing process. The study presents a promising way of depurating Cd‐contaminated rice, and meanwhile it reduces the risk of heavy metal causing food safety issues effectively.     

聚磷酸钠对大豆分离蛋白的修饰研究

采用多聚磷酸钠对大豆分离蛋白进行磷酸化修饰,研究磷酸化反应的工艺条件及改性后大豆分离蛋白几种功能特性的变化。结果表明:当大豆分离蛋白4%、三聚磷酸钠9%、反应初始pH9、反应时间3h时,磷酸化程度最大;磷酸化后的大豆分离蛋白的溶解性、乳化性以及粘度都有不同程度的改善。     

Rice Dreg Protein as an Alternative to Soy Protein Isolate: Comparison of Nutritional Properties

Rice dreg protein could be a valuable source of plant-based proteins, as an alternative to soy proteins in some food products. Here, nutritional properties of rice dreg protein were compared with those of soy protein isolate. The protein content of rice dreg protein was approximately 62.6 g/100 g sample, with large amounts of fat, carbohydrate, and ash. The denaturation temperatures of rice protein isolate from rice dreg protein were 47.4 and 97.2°C, respectively. This indicated that these proteins could be denatured during rice syrup processing to form aggregates, but were relatively more stable than rice endosperm protein and soy protein isolate. The main amino acids in rice dreg protein and rice protein isolate were Glu, Pro, Arg, Asp, and Leu, with Lys as the lowest content. Most of essential amino acids and nutritional parameters of rice protein isolate and rice dreg protein met the suggested nutritional requirements for a child according to FAO/WHO, and were relatively higher than those of soy protein isolate. In addition, rice protein isolate showed better digestibility than soy protein isolate during four hours sequential pepsin and pancreatin digestions. The final digestibility value was 96.66% for rice protein isolate compared to 91.41% for soy protein isolate. Thus rice dreg protein could potentially replace soy proteins as a good source of value-added protein for human nutrition in response to the increasing demand for plant proteins.     

复合米糠蛋白粉的研制与营养价值评价

以米糠蛋白粉和乳粉为原料,根据食物蛋白质互补原理并进行计算,得出最佳互补效果的复合米糠蛋白粉配方。通过大鼠生长实验和代谢实验对复合米糠蛋白粉进行营养价值评价并与乳粉和酪蛋白比较分析。结果表明：复合米糠蛋白粉的营养价值得到显著提高,校正蛋白质功效比值为2.45;蛋白质真消化率、生物学价值和蛋白质净利用率分别为(89.12±1.43)%、79.34±1.36、(67.53±1.24)%,各项指标均优于乳粉,与酪蛋白非常接近。复合米糠蛋白粉是优质的植物蛋白、动物蛋白复配高蛋白营养产品。     

可食性大豆分离蛋白膜的研究进展

随着人们对环境保护和食品安全的日益重视，在食品包装材料的开发上正发生较大变革，其中，可食性包装材料的研究特别引人注目。本文简单介绍了可食性大豆分离蛋白(SPI)膜的成膜机理、营养特性、机械特性、透气特性等，并综述了国内外在改善膜的应用特性方面取得的积极进展。     

米糠多糖-乳清分离蛋白美拉德反应及其产物表征

目的：通过米糠多糖(rice bran polysaccharide,RBP)与乳清分离蛋白(whey protein isolate,WPI)非酶褐变反应,探究反应时间对美拉德反应的影响,开发一种新型乳化剂制备纳米乳液包埋脂溶性物质。方法：RBP与WPI在干热条件下反应不同的时间,以A_{294 nm}、褐变程度、色泽变化、游离氨基含量等的变化监控美拉德反应进程,对美拉德反应产物的分子质量、粒径、乳化活性、乳化稳定性、微观结构进行表征,并用美拉德反应产物制备大豆油纳米乳液。结果：A_{294 nm}、褐变程度、色泽变化及游离氨基含量的变化,表明混合体系发生了美拉德反应,且随反应时间的延长产物颜色变暗;美拉德反应产物分子质量为17 kDa;反应12 h时的产物粒径分布较为均匀;RBP接枝到WPI分子上显著提高了WPI的乳化活性和乳化稳定性(P<0.05);WPI-RBP(12 h)@纳米乳液比WPI@纳米乳液更稳定、粒径均匀,能抵抗酸性条件下和盐离子存在条件下对乳液的不利影响。结论：WPI与RBP间的美拉德反应有效改善了WPI的特性,可作为一种新型...     

发芽糙米蛋白质营养价值评价

通过对发芽糙米蛋白质和氨基酸组成特性变化的分析,评价了发芽糙米蛋白质的营养价值。发芽使糙米蛋白质、总氨基酸、必需氨基酸、支链氨基酸、鲜味氨基酸、抗氧化氨基酸的含量增加,必需氨基酸指数提高;增加的蛋白质主要是谷蛋白。发芽后赖氨酸和苏氨酸的含量增加较明显,但仍是限制性氨基酸;EAA组成模式更加符合FAO/WHO标准。发芽在一定程度上提高了糙米蛋白质的营养价值。     

大豆分离蛋白酶法有限水解工艺过程及动力学分析

采用pH-stat法在pH8.0,T=50℃条件下,以Alcalasa酶对大豆分离蛋白进行有限水解处理,探讨了酶与底物摩尔浓度比[E]/[S]和反应时间t对产物水解度及溶解性的影响;研究了相应的有限水解(x＜6.0)过程的动力学特征。实验结果显示,控制主要影响因素为[E]/[S]＜0.4％,pH8.0和T=50℃条件下,在25min内可使产物的水解度x达到约6.0％,并且产物在酸性pH范围的溶解性明显改善。对实验结果的分析显示,水解过程中底物与酶之间的相互作用引起酶的抑制和失活。在此基础上推导出底物存在临界浓度,在实验条件下,其值为96.77mg/ml。     

酪蛋白磷酸肽钙- 乳清蛋白复合膜物理性质的研究

在乳清分离蛋白(WPI)基础膜中引入酪蛋白磷酸肽钙(CPPs)制备成富钙的单层复配膜和双层复合膜,并对膜的有关物理性质(机械强度、含水量、水蒸气透过系数)进行评价。单层复配膜中CPPs 与WPI 的最大百分比为8%,总钙含量最高为0.59%。CPPs 的添加量对所测膜的物理性质没有显著影响(P ＞ 0.05)。双层复合膜可使总钙含量高达28% 以上,但同时也使膜的机械强度较单层复配膜降低近一半,且含水量显著降低(P ＜ 0.05)。     

大豆分离蛋白及7S、11S蛋白对肝脏的保护作用

为探究大豆蛋白是否具有保肝作用,本文采用昆明种雄性小鼠作为实验对象,建立四氯化碳急性肝损伤模型,通过灌胃方式1次/d给予不同组别小鼠不同剂量、不同成分(大豆分离蛋白SPI、11S、7S)的蛋白(300mg/kg、500mg/kg、700mg/kg),并设一组大豆蛋白饲料组(SPI含量为20%),持续15天,于末次给药后注射CCl4油溶液(10ml/kg,0.15%)。通过测定血清中谷丙转氨酶(ALT)、谷草转氨酶(AST)活力,肝脏中丙二醛(MDA)、谷胱甘肽(GSH)含量、谷胱甘肽过氧化物酶(GSH-Px)活力及肝脏指数评价保肝效果。结果显示：每天摄入700mg/kg的SPI对由四氯化碳致肝损伤鼠有显著的保护作用;与模型组相比,700mg/kg的7S蛋白能显著抑制由四氯化碳引起的血清中ALT、AST活力升高和小鼠肝脏中MDA含量的升高,并能显著提高其肝脏中的GSH含量、GSH-Px活力(P＜0.05)。结论：大豆蛋白可抵御CCl4致化学性肝损伤,其中的7S蛋白是主要的保肝活性成分。     

大米蛋白开发利用

我国具有丰富的大米蛋白资源,它们主要是稻米深加工副产品米糠和米渣,大米蛋白不仅具有优良营养价值,还具有潜在生理保健功能;从米渣中获得大米分离蛋白方法不宜用碱法提取而应该是纯化;多种酶制剂的应用对米糠蛋白提取具有重要意义;大米蛋白适度水解不仅可用于改善食品蛋白质营养和加工性能,还可用于生产多种生物活性肽。     

猪肉肠中亚麻籽胶、大豆分离蛋白、酪蛋白的相互作用研究

研究猪肉肠中亚麻籽胶、大豆分离蛋白和酪蛋白的相互作用。采用析因试验设计,在猪肉肠加工过程中,同时添加不同质量分数的亚麻籽胶、大豆分离蛋白和酪蛋白,分析上述添加物对产品保水性、保油性的影响。结果显示：添加亚麻籽胶对猪肉肠在60℃条件下烘20min的保水能力有极显著的影响(P＜0.01),然而,亚麻籽胶对猪肉肠在60℃条件下烘40min的保水能力没有显著的影响(P＞0.05)。酪蛋白的添加对猪肉肠在60℃条件下烘20min和40min的保水能力有显著的影响(P＜0.05)。保水能力上,从高到低依次为：酪蛋白、亚麻籽胶、大豆分离蛋白。亚麻籽胶的添加显著地影响了用乙醚浸提20、40、60min猪肉肠的保油性(P＜0.05),大豆分离蛋白和酪蛋白也有类似结果。大豆分离蛋白对猪肉肠用乙醚浸提60min的保油性有极显著性影响(P＜0.01),并且,亚麻籽胶与大豆分离蛋白有显著的交互作用(P＜0.05)。在保油能力上,大豆分离蛋白强于酪蛋白。     

大豆分离蛋白O/W型乳液膜的制备及其性质研究

摘要：为提高大豆分离蛋白膜的性质,制备以大豆分离蛋白（SPI）为原料的O/W乳液膜,采取单因素实验法比较O/W乳液膜与SPI膜的差异性,探究不同SPI质量浓度（20、30、40、50和60 mg/mL）对O/W乳液膜性能及结构的影响。结果表明：O/W乳液膜的遮光性、机械性能、耐水性及热稳定性要优于SPI膜。随着SPI质量浓度的增加,O/W乳液膜的拉伸强度随之增加,断裂伸长率降低。蛋白质量浓度为60 mg/mL时,O/W乳液膜的抗拉强度达到最大值为7.19 MPa,比蛋白膜的抗拉强度高出33%。利用扫描电子显微镜（SEM）、傅里叶红外光谱（FTIR）和差式扫描量热仪（DSC）对O/W乳液膜蛋白分子间的相互作用进行分析,乳液膜的Tg为100 ℃,且红外光谱中酰胺Ⅲ带和1630 cm-1峰值发生了变化,表明共混组分之间的作用力增强,蛋白质形成了致密且稳定的网络结构。     

美拉德反应对乳清分离蛋白及其水解物抗氧化性的影响

以乳清分离蛋白及其蛋白水解物为原料分别与半乳糖发生美拉德反应,研究两者美拉德反应的褐变程度、接枝度及产物荧光光谱的变化,同时以乳清分离蛋白和蛋白水解物作对照,研究两者美拉德反应产物的抗氧化性。结果表明:乳清分离蛋白及其水解物美拉德反应的褐变程度、接枝度及产物的抗氧化性均在4 h达到最大。其中,乳清分离蛋白及其水解物与半乳糖美拉德反应的褐变程度和接枝度最大值分别为1.114、18.431%和1.413、28.273%;两者美拉德反应产物的还原力、2,2’-联氨-二(3-乙基-苯并噻唑-6-磺酸)二铵盐自由基清除能力和1,1-二苯基-2-三硝基苯肼自由基清除能力分别为0.605、46.29%、61.77%和0.923、69.81%、78.43%,均显著高于对照组(P0.05)。同时,内源荧光光谱发现,美拉德反应改变了乳清分离蛋白及其水解物的构象,使二者的结构更加松散。     

米胚分离蛋白营养和功能性评价

利用氨基酸自动分析仪检测米胚4种Osborne分离蛋白中的氨基酸组成,以氨基酸评分(AAS)、蛋白质功效比值(PER)、生物价(BV)及体外消化率为评价标准,对米胚蛋白各组分的营养价值进行评价。结果表明:谷蛋白的氨基酸评分最高,为80.90,清蛋白、球蛋白、谷蛋白符合FAO/WHO推荐的参考蛋白模式,其PER值与优质蛋白的衡量标准值2.00接近,BV值较高,在体外的营养消化效率较好,醇溶蛋白的品质相对较差。对米胚四种蛋白的起泡性、起泡稳定性、吸水性、吸油性等功能性质进行测定,结果表明:pH 5时4种蛋白的起泡性最低,起泡稳定性最好;清蛋白、球蛋白的吸水性比醇溶蛋白、谷蛋白好,醇溶蛋白的吸油性最好;米胚蛋白各组分的表面疏水性较高,需进一步进行改性处理。     

Evaluation of Poultry Protein Isolate as a Food Ingredient: Physicochemical Properties and Sensory Characteristics of Marinated Chicken Breasts

The possibilities of replacing soy protein isolate (SPI) and reducing the amount of phosphate in marinated chicken breasts using poultry protein isolate (PPI) were investigated. PPI, prepared from mechanically separated turkey meat through the pH‐shift technology, was used as a marinade ingredient for chicken breasts at 2 different concentrations (1.0% and 1.5%, w/w on a dry weight basis). Product characteristics were compared to samples marinated with salt, phosphate, or SPI. All the 5 treatments were subjected to instrumental and sensory analyses. Tumbling yield, drip, and cooking losses as well as expressible moisture showed that PPI can be used as a substitute for SPI in brine. The sensory analysis revealed that there were no differences among treatments in terms of appearance, color, flavor, saltiness, juiciness, tenderness, and overall acceptability of the marinated chicken breasts. However, chicken breasts marinated with phosphate had significantly higher aroma acceptability scores than those treated with 1% PPI.     

酶法水解乳清分离蛋白制备纳米纤维

采用天冬氨酸内切酶(Asp endoproteinase,AspN)在37℃诱导乳清分离蛋白(whey protein isolate,WPI)制备蛋白质纳米纤维(protein nanofibrils,PNFs),考察WPI不同水解时间对产物PNFs形貌的影响。利用透射电子显微镜、原子力显微镜、小分子蛋白质十二烷基硫酸钠-聚丙烯酰胺凝胶电泳、硫磺素T荧光、红外光谱以及激光散射法对PNFs及形成过程进行表征。结果显示,该方法制备的产物PNFs呈乳白色,AspN水解得到的5 kD左右的多肽为构筑单元,β-折叠为PNFs稳定存在的主要二级结构,PNFs平均粒径随水解时间延长而增大。酶法制备PNFs解决了酸法中的褐变问题,有望拓展其在食品领域的应用。     

Effect of Extraction pH and Temperature on Isoflavone and Saponin Partitioning and Profile During Soy Protein Isolate Production

ABSTRACT: Soy protein isolates (SPIs) are produced industrially using methods using various protein extraction temperatures and pH values. The effects of process temperature (25°C or 60°C) and pH (8.5, 9.5, or 10.5) on isoflavone and group B saponin extraction, partitioning, and profile during bench-scale SPI production were evaluated. Protein, isoflavone, and saponin extraction increased with increasing temperature and pH. Substantial quantities of isoflavones and saponins remained in the insoluble fraction waste stream. Isoflavones were also lost to the whey waste stream, whereas saponins were not detected in the whey. Neutralization of SPI samples at the time of analytical extraction increased measured isoflavone concentrations for the pH 8.5 process extraction treatments, whereas neutralization substantially increased measured saponin concentrations in SPIs for all process extraction treatments. Malonylglucoside isoflavones were primarily converted to β-glucoside forms as temperature and pH were increased, and these conditions caused conversion of αg, βg, and βa saponins to saponin V, I, and II forms, respectively. Analytical extraction pH should receive careful consideration when analyzing soy matrices for isoflavones and saponins.