大豆原料对分离蛋白加工及功能特性的影响

为研究不同大豆品种对大豆分离蛋白加工及功能特性的影响,选取了5个品种的大豆为原料,对比分析了原料对大豆分离蛋白得率、粗蛋白含量、凝胶特性、持水性、乳化特性的影响。结果显示,以冀豆12为原料制备的大豆分离蛋白得率最高,五星4最低;采用质构分析法对凝胶特性进行分析,以冀豆12为原料生产的大豆分离蛋白的凝胶强度值最高,五星3号最低;持水性最高为冀豆12,最低为五星3号;乳化性最高为五星3号,与冀豆12相差不大,乳化性最低为冀豆20。综上,以冀豆12为原料制备的大豆分离蛋白具备极高的持水性、凝胶特性和极佳的乳化特性,冀豆12适合高凝胶、高持水力、高乳化性的大豆分离蛋白的生产。     

大豆乳清蛋白的热促凝聚及其对分离蛋白功能性的影响

分别在pH8.0和pH4.5对"碱提酸沉"法制备大豆分离蛋白过程中所得提取液进行热处理,研究了大豆乳清蛋白的热促凝聚效果及其对所制备分离蛋白功能性的影响。结果表明:加热处理可降低大豆乳清中乳清蛋白的含量,在pH8.0和pH4.5时提取液经70℃加热10 min分别使25.7%和40%乳清蛋白转移到分离蛋白产品中。以普通分离蛋白为对照,对3种分离蛋白产品进行功能性分析,发现3种产品均在pH4.5~4.8的范围内溶解度最小,70℃加热10 min所制备分离蛋白的持水性明显高于普通分离蛋白,但其持油性、起泡性、泡沫稳定性和乳化性均低于普通分离蛋白,而乳化稳定性无显著差异。     

马铃薯浓缩蛋白制品的功能性质评价

实验主要比较了马铃薯全蛋白粉、HCL沉淀蛋白 ,FeCl3沉淀蛋白、大豆分离蛋白以及酪蛋白的溶解度、乳化力和起泡力。结果得出上述各种蛋白制品中蛋白质在pH 8 0时的溶解度分别为 70 %、 2 7%、 6 5%、 97%和 90 % ;马铃薯全蛋白粉的乳化力和起泡力与大豆分离蛋白相当     

三种大豆分离蛋白的比较研究和物化特性相关性分析

对3种不同大豆分离蛋白的基本化学组成、游离巯基、二硫键和表面疏水性进行了测定;对3种不同大豆分离蛋白的粘度、乳化性和凝胶性进行了分析;采用SPSS软件对物化特性与大豆分离蛋白的基本化学组成、游离巯基、二硫键和表面疏水性的相关性进行了分析,确定了大豆分离蛋白的粘度、乳化性和凝胶性与蛋白质含量、二硫键、游离巯基含量的相关性。     

大豆分离蛋白酶解产物功能特性的研究

研究了大豆分离蛋白的碱性蛋白酶和木瓜蛋白酶水解产物各种加工功能性质的变化趋势,并比较了两种酶在各个不同酶解时间下水解产物的各种功能性质。结果表明:大豆分离蛋白酶解产物比大豆分离蛋白的溶解性、乳化性、发泡能力和吸油性都有所改善;大豆分离蛋白木瓜蛋白酶水解产物保水性、乳化性、吸油性、发泡能力、粘度、凝胶性均优于大豆分离蛋白碱性蛋白酶水解产物。     

pH、离子强度等因素对椰子分离蛋白溶解性和乳化性的影响

分析椰子分离蛋白(CPI)溶解性、乳化性、乳化稳定性及pH、离子强度和温度对这些功能特性的影响。结果表明,与大豆分离蛋白和棉籽分离蛋白相比,椰子分离蛋白具有较好的溶解性、乳化性、吸油性和吸水性;而pH、离子强度和温度等因素对椰子分离蛋白的溶解性、乳化性和乳化稳定性有显著影响。在等电点附近,椰子分离蛋白表现出最低的溶解性与乳化性;低离子强度可提高椰子分离蛋白的溶解性和乳化性,而高离子强度降低了其溶解性和乳化性;CPI在60℃时有较好的溶解性和乳化性。     

速溶性大豆分离蛋白生产工艺优化

以中性蛋白酶和木瓜蛋白酶复配为工具酶,以水解度为指标,通过单因素试验与响应面分析对大豆分离蛋白的酶解工艺进行优化,并添加磷脂、蔗糖,以溶解性为指标优化调配工艺,提高其速溶性.结果得到最佳酶解工艺参数为pH7.08,温度51.6℃,酶(木瓜蛋白酶与中性蛋白酶按质量比1∶1复配)添加量22.45 mg·g-1,酶解时间3h;在此酶解条件下,大豆分离蛋白的水解度达20.3％,溶解度达72％.最佳调配工艺为磷脂添加量0.8％,蔗糖添加量3.0％,最终产品溶解度达92.9％.样品溶于水后下沉快,易溶解,无团块.     

大豆蛋白的甘露聚糖糖基化研究

将大豆分离蛋白与甘露聚糖糖基化生成大豆糖蛋白,力求为工业化生产大豆糖肽作为原料.采用SDS-PAGE电泳技术,OPA法测定大豆蛋白的接枝度,结果大豆分离蛋白的7S和11S中各亚基均参与了糖基化反应,70℃和80℃的蛋白接枝度在30%左右;糖蛋白的溶解性测定结果显示经过糖基化之后的大豆糖蛋白溶解性有显著提高并且等电点向酸性方向偏移,糖基化之后的蛋白含糖量随糖基化温度升高而增加.     

用蛋白酶组合对大豆分离蛋白改性的研究

用蛋白酶组合对大豆分离蛋白进行有限水解,所得水解液不苦,具有良好的风味.改性后的大豆分离蛋白的氮溶指数由未水解的82提高到95,20℃时溶解度在25%以上.经正交试验得到的大豆分离蛋白水解的最佳工艺参数为:加酶量,0.55%(w/w);固液比,1∶8(w/w);酶解时间,60 min.     

大豆分离蛋白在千叶香丝中的应用及工艺条件的研究

主要研究了大豆分离蛋白在千叶香丝中的应用以及千叶香丝在加工过程中的品质影响因素。结合质构数据和感官评价结果发现,在生产工艺中的油料比、料水比以及蒸煮温度对千叶香丝质量的影响较大。通过正交试验,确定工艺条件为大豆油与大豆分离蛋白的比例为5:8,大豆分离蛋白与冰水质量比为1:5.5,蒸煮温度为85℃时,千叶香丝的乳化坯子弹性可达0.965。结合感官评定结果,确定千叶香丝的最佳生产工艺条件为:大豆油与大豆分离蛋白的比例为5:8,大豆分离蛋白与冰水质量比为1:6,蒸煮温度为85℃。     

超声波对大豆蛋白增溶作用的研究

为了提高大豆深加工产品的得率和蛋白质含量，利用超声波处理大豆经湿磨后的浆潭混合液态物，产生超声空化效应，提高大豆蛋白的溶出率，减少大豆蛋白在豆渣中的残留，试验表明：超声提取技术能提高大豆蛋白的溶出率，从而使豆乳蛋白含量相对提高6.6%，豆乳干物质重量相对提高11.6%。该技术对于传统大豆制品及现代大豆加工新产品如豆奶、速溶豆粉及分离蛋白、农缩蛋白等产品的生产均具有提高蛋白含量、增加得率的效用。     

Properties of protein concentrates and hydrolysates from Amaranthus and Buckwheat

Protein concentrates and pepsin hydrolysates were made after isoelectric precipitation of the proteinaceous liquor from wet-milling of grain of five Amaranthus and one buckwheat genotype. The Amaranthus protein concentrates exhibited better solubility, foaming, and emulsification than two commercial soy protein controls. Many protein properties depend on solubility, and Amaranthus protein concentrates were more soluble than soy protein isolate. The buckwheat protein concentrate was highly soluble with excellent emulsification, but poor foaming ability. Partial pepsin hydrolysis further improved solubility of the protein concentrates and also altered their foaming property. Fractionation and subsequent characterization of protein concentrates revealed that glutelins, albumins, and globulins predominated, with prolamins present in minor quantity. SDS-PAGE showed that globulins and glutelins were comprised of several subunits with varying molecular weights from relatively high to low while albumins were mostly of low molecular weight. The prolamin fraction of the buckwheat concentrate was comprised of intermediate to low molecular weight subunits while those of Amaranthus concentrates were only of low molecular weight. This study demonstrated the feasibility of producing potentially useful functional protein concentrates as by-product of Amaranthus and buckwheat starch extraction.     

储存条件对大豆分离蛋白凝胶性的影响

大豆分离蛋白的凝胶性在食品加工中得到了广泛应用。本文针对不同的环境温度、时间、包装方式等因素,对储存后大豆蛋白的凝胶性进行了研究。通过优化储存条件,使其在常温,通风的条件下,减少凝胶功能性的损失,达到最佳使用效果。     

Comparison of functional and structural properties of native and industrial process-modified proteins from long-grain indica rice

Rice proteins, as a cheap plant protein source from the by-products of rice dreg processing, could potentially replace commonly used proteins such as soy and whey proteins in selected food products. In this study, the functional properties, surface hydrophobicity (H₀), sulfhydryl and disulfide bond contents, thermal properties, as well as secondary structures of native rice endosperm protein (REP) and processed rice dreg protein (RDP) extracted from long-grain indica rice, were compared. RDP was found to have a higher solubility associated with its relatively higher emulsifying and foaming properties than REP, as well as its water/oil holding capacity, although it was a denatured protein. The emulsifying properties were dependent on the solubility and H₀, while solubility was also related to the disulfide bond contents. Distinct differences in H₀, thermal properties, and disulfide bond contents between REP and RDP could be due to the conformational changes, as the industrial processing steps in the production of rice syrups caused an increase in β-turns at the expense of β-sheets and random coils of REP, leading to the unfolding of β-sheets into higher-ordered supramolecular structures for RDP, which could be responsible for its better functional properties.     

Comparison of functional and structural properties of native and industrial process-modified proteins from long-grain indica rice

Rice proteins, as a cheap plant protein source from the by-products of rice dreg processing, could potentially replace commonly used proteins such as soy and whey proteins in selected food products. In this study, the functional properties, surface hydrophobicity (H₀), sulfhydryl and disulfide bond contents, thermal properties, as well as secondary structures of native rice endosperm protein (REP) and processed rice dreg protein (RDP) extracted from long-grain indica rice, were compared. RDP was found to have a higher solubility associated with its relatively higher emulsifying and foaming properties than REP, as well as its water/oil holding capacity, although it was a denatured protein. The emulsifying properties were dependent on the solubility and H₀, while solubility was also related to the disulfide bond contents. Distinct differences in H₀, thermal properties, and disulfide bond contents between REP and RDP could be due to the conformational changes, as the industrial processing steps in the production of rice syrups caused an increase in β-turns at the expense of β-sheets and random coils of REP, leading to the unfolding of β-sheets into higher-ordered supramolecular structures for RDP, which could be responsible for its better functional properties.     

Oat protein solubility and emulsion properties improved by enzymatic deamidation

Oat protein produced by a dry milling process was enzymatically deamidated by a food-grade protein-glutaminase (PG), and the effects on structure, solubility and emulsifying properties of oat proteins were studied. The reactions were conducted at neutral pH and low salt concentration conditions. Oat proteins were deamidated up to a deamidation degree of 59%. The solubility of proteins doubled. Oil-in-water emulsions prepared with the native and deamidated oat proteins differed as the emulsions prepared from oat proteins with high deamidation degree had a more uniform oil droplet particle size and longer stability. Fourier transform infrared (FT-IR) analysis demonstrated that oat protein secondary structure became more flexible by deamidation. Protein-glutaminase mediated deamidation appeared to be a promising technique to improve oat protein functionality such as emulsifying ability and solubility.     

Anti-melanogenic property of geoditin A in murine B16 melanoma cells

Geoditin A, an isomalabaricane triterpene isolated from marine sponge Geodia japonica, has been demonstrated to induce apoptosis in leukemia HL60 cells and human colon HT29 cancer cells through an oxidative stress, a process also interfering with normal melanogenesis in pigment cells. Treatment of murine melanoma B16 cells with geoditin A decreased expression of melanogenic proteins and cell melanogenesis which was aggravated with adenylate cyclase inhibitor SQ22536, indicating melanogenic inhibition was mediated through a cAMP-dependent signaling pathway. Immunofluorescence microscopy and glycosylation studies revealed abnormal glycosylation patterns of melanogenic proteins (tyrosinase and tyrosinase-related protein 1), and a co-localization of tyrosinase with calnexin (CNX) and lysosome-associated membrane protein 1 (LAMP-1), implicating a post-translational modification in the ER and a degradation of tyrosinase in the lysosome. Taken together, potent anti-melanogenic property and the relatively low cytotoxicity of geoditin A have demonstrated its therapeutic potential as a skin lightening agent.