鹌鹑蛋功能特性及其影响因素

测定了鹌鹑蛋乳化性、起泡性、持水性等功能特性,并探讨了蔗糖、温度、pH值、氯化钠等因素对蛋白起泡性及其稳定性和蛋黄乳化性的影响。结果表明,鹌鹑蛋白的起泡性为7.33%,泡沫稳定性为63.49%,乳化性为41.51%,持水性约17.14%;鹌鹑蛋黄的起泡性为10%,泡沫稳定性为59.73%,乳化性为46.82%;鹌鹑全蛋液的起泡性为11%,泡沫稳定性为63.95%,乳化性为43.99%,持水性约18.28%。蔗糖能在一定范围内提高泡沫稳定性,适当加热可改善蛋白起泡性,蛋白起泡性随NaCl增加而有较大幅度提高。鹌鹑蛋黄乳化性随蔗糖浓度增大而提高,10～60℃内随温度升高而提高,加入氯化钠能明显提高蛋黄乳化性。pH值对蛋白起泡性和泡沫稳定性、蛋黄乳化性的影响均呈动态变化。     

胡麻籽分离蛋白的溶解性与起泡性研究

为促进胡麻籽分离蛋白在食品工业中的应用,研究了pH值、盐浓度、蛋白质浓度等因素对其水溶性、起泡性和泡沫稳定性的影响。pH值对胡麻籽分离蛋白溶解度的影响呈典型的V形曲线。NaCl浓度为0.4mol/L前后胡麻籽分离蛋白表现出明显的盐溶与盐析效应。在0.1%～0.8%范围内,提高蛋白质浓度能增强起泡性与泡沫稳定性。在等电点附近,胡麻籽分离蛋白的起泡性最差但却具有最强的泡沫稳定性。NaCl对胡麻籽分离蛋白的起泡性的影响与其对溶解性的影响有相同的趋势。蔗糖能提高胡麻籽分离蛋白的泡沫稳定性,但当浓度高于5%时,对起泡性有负面影响。     

马铃薯淀粉废水蛋白的功能特性

以碱提酸沉法制备的马铃薯淀粉废水蛋白为原料,分别考察了pH值、NaCl浓度和温度对蛋白功能特性（溶解性、持水能力、乳化性及乳化稳定性、起泡性及泡沫稳定性）的影响。结果表明,pH值、NaCl浓度和温度对蛋白的功能特性产生不同程度的影响。在等电点（pH 4.0）时,马铃薯蛋白表现出最低的溶解性、持水性、乳化性、乳化稳定性及起泡性,而泡沫稳定性最好。在较低NaCl浓度（＜0.2 mol/L）时,蛋白溶解性、持水能力、乳化性和乳化稳定性随NaCl浓度的增加而提高,而高浓度的NaCl（＞0.2 mol/L）对上述性质具有抑制作用;蛋白的起泡性和泡沫稳定性在NaCl浓度为0.4 mol/L时具有最大值。在4～80 ℃范围内,蛋白质的各项功能性质随温度的升高均呈现先增加后降低的趋势,且溶解性、持水性、乳化稳定性、起泡性及泡沫稳定性在40 ℃时最佳,乳化性在60 ℃最佳。     

蒸汽爆破辅助提取油茶籽蛋白及其功能性质分析

研究了蒸汽爆破结合碱溶酸沉法提取油茶籽蛋白工艺,确定了最佳提取条件,同时分析了pH、蛋白质量浓度、NaCl浓度和蔗糖浓度对蒸汽爆破处理前后油茶籽蛋白功能性质的影响。结果表明:最佳提取条件为蒸汽爆破压力0. 8～2. 3 MPa、蒸汽爆破时间30～120 s、料液比1∶10、提取温度40℃、pH 10、提取时间50 min,在此条件下,油茶籽蛋白提取率为71. 01%,显著高于未经蒸汽爆破处理的58. 74%;经蒸汽爆破处理得到的油茶籽蛋白吸油性和吸水性均有所提高; pH、蛋白质量浓度、NaCl浓度均对油茶籽蛋白的起泡性和泡沫稳定性、乳化性和乳化稳定性有不同程度的影响;蔗糖浓度对油茶籽蛋白起泡性作用比较明显,但对泡沫稳定性无显著改善作用,对乳化性、乳化稳定性起到改善作用。     

不同因素对白果蛋白持油性、持水性和起泡性的影响

以白果蛋白为研究对象,研究温度对其持油性、持水性和pH值、NaCl、蔗糖对其起泡性的作用规律。结果表明:当温度达到40℃时,白果蛋白持油性达到最大值(3.32%),当温度达到45℃时,持水性达到最大值2.97%;当NaCl浓度为0～0.4mol/L时,白果蛋白的起泡能力和泡沫稳定性与NaCl浓度呈正相关,当NaCl浓度高于0.6mol/L时,过高的离子强度使白果蛋白的起泡能力和泡沫稳定性降低;蔗糖的加入将大幅度提高白果蛋白的泡沫稳定性,而对起泡能力提高幅度较小;pH值对白果蛋白的起泡能力和泡沫稳定性影响较大,当pH值为3～11时,起泡性较差,当pH值小于3时,起泡能力和泡沫稳定性与pH值呈负相关,当pH值大于11时,起泡能力和泡沫稳定性与pH值呈正相关,当pH值等于13时达到最高值。     

羊肝蛋白稳定性及NaCl质量分数对其功能特性的影响

采用差式扫描量热法、激光粒径分布仪等仪器分析法研究了羊肝蛋白的稳定性,同时研究了NaCl质量分数(0.0%,1.8%,3.6%)对羊肝蛋白的乳化性与起泡性等功能特性及分子量分布和表面疏水性的影响。结果表明:随着NaCl质量分数的增加,水溶性羊肝蛋白(Water soluble liver proteins,WSLP)和盐溶性羊肝蛋白(Salt soluble liver proteins,SSLP)的表面疏水性也增加;SSLP的变性温度为87.9℃,高于WSLP的变性温度(74.4℃),表现出较好的热稳定性;WSLP的粒径分布较为集中,且电位绝对值小于SSLP;WSLP和SSLP均显示出良好的乳化性能和泡沫稳定性,NaCl质量分数的增加降低了WSLP的乳化性能,而对SSLP的乳化性能则没有明显影响。NaCl质量分数为1.8%时可提高WSLP和SSLP的起泡能力,而且不会影响其泡沫稳定性;而NaCl质量分数(3.6%)的进一步增加会降低起泡能力和泡沫稳定性。     

牛血清白蛋白的乳化和起泡特性

研究蛋白质量浓度、pH 值、CaCl2 质量浓度和温度对牛血清白蛋白(BSA)的乳化性、乳化稳定性、起泡性和起泡稳定性的影响。结果表明：蛋白质量浓度为0.1g/100mL 时乳化性和乳化稳定性最大,pH 值为5 时乳化性和乳化稳定性最小,乳化性随着CaCl2 质量浓度的增加而缓慢增大,乳化稳定性随着CaCl2 质量浓度的增加而减小,60℃时乳化性较好,乳化稳定性在60℃后显著下降;随着蛋白质质量浓度的增加,起泡性呈上升趋势,起泡稳定性先上升后下降,在质量浓度为1.5g/100mL 时起泡稳定性最好;pH 值为5 时起泡性最小,而此时起泡稳定性最好;CaCl2 质量浓度对起泡性和起泡稳定性没有影响。     

桑叶蛋白的功能特性研究

采用超声波辅助提取结合盐酸沉析法提取桑叶蛋白,研究pH值、离子强度、蔗糖质量浓度和温度对桑叶蛋白功能特性的影响。结果表明：远离其等电点时,桑叶蛋白具有良好的持水性、溶解度、乳化性及乳化稳定性、起泡性;桑叶蛋白的持水性、溶解度和起泡性与NaCl浓度(0～1.0mol/L)呈正相关,而过高的离子强度(NaCl浓度高于0.6～0.8mol/L)会使桑叶蛋白的乳化性和乳化稳定性下降;蔗糖的加入会增加桑叶蛋白的持水性,但会降低其溶解度和起泡性,对桑叶蛋白的乳化性和乳化稳定性影响不大;桑叶蛋白的吸油性和起泡性与温度(4～80℃)呈正相关,持水性、溶解度、乳化性及乳化稳定性于60℃时最好。     

苦杏仁蛋白的功能特性

采用稀盐溶液浸提及等电点盐析相结合的方法提取制备苦杏仁蛋白,研究pH值、NaCl浓度、蛋白质量浓度和温度等因素对苦杏仁蛋白功能特性(溶解性、持水性、吸油性、乳化性及乳化稳定性、起泡性及起泡稳定性)的影响。结果表明：在等电点pI附近时,苦杏仁蛋白的溶解性、持水性、乳化性及乳化稳定性、起泡性最差;在较低NaCl浓度范围内(0～0.8mol/L)提高NaCl浓度可促进蛋白溶解性、乳化性及乳化稳定性、起泡性及起泡稳定性的提高,而较高的NaCl浓度对蛋白功能特性提高具有抑制作用;当蛋白质量浓度达到一定水平时(3～4g/100mL),蛋白功能特性(乳化性及乳化稳定性、起泡性及起泡稳定性)提高趋于平缓;在适宜的温度范围内,提高温度可有效提高苦杏仁蛋白各项功能特性,但当温度继续上升,各项功能特性持续降低。     

葡萄籽蛋白的起泡性和泡沫稳定性研究

以葡萄籽为原料,首先采用碱提酸沉法提取葡萄籽蛋白,然后测定了其等电点,最后研究了蛋白浓度、pH值、NaCl浓度以及蔗糖浓度对葡萄籽蛋白的起泡性和泡沫稳定性的影响。结果表明：葡萄籽蛋白干粉得率为8.0%,干粉中蛋白质含量为70.11%,蛋白的等电点为pI=3.8;各因素对葡萄籽蛋白的起泡性和泡沫稳定性均有不同程度的影响。     

Amino acid composition,foaming, emulsifying properties and surface hydrophobicity of mustard protein isolate as affected by pH and NaCl

Amino acid composition, protein hydrophobicity, foaming and emulsifying properties of mustard protein isolate at pH 3, 5, 7 and in 0.05 and 0.1 m NaCl were studied. Glutamic (19.18 ± 0.30%) and aspartic (7.49 ± 0.11%) acids were the dominants. Foaming ability was enhanced by NaCl. Time to reach 75 mL foam was 23% higher in water than in NaCl. Drained volume after 10 min was concentration dependent and was the lowest in 0.05 and 0.1 m NaCl at protein concentration of 2.5% and 5%. The emulsifying properties were pH and concentration dependent, and the best results were obtained at pH 3, corresponding to the highest positive charge density of the protein surface. The highest emulsion stability (90.22 ± 3.52%) was obtained in 0.05 m NaCl and 5% protein concentration, whereas the lowest (63.00 ± 1.06%) was in water at all protein concentrations. Protein hydrophobicity was low and depended of pH but not of NaCl.     

不同提取方法及因素对亚麻蛋白功能性质的影响

通过单因素和正交试验优化高速剪切、超声酶解两步水解黄精工艺,并用黄精水解液和糯米混合发酵酿制新型黄精黄酒。结果表明,黄精原料高速剪切工艺参数为剪切时间50 min、剪切pH 2、剪切速率14 000 r/min、料液比1∶50（g∶mL）;黄精滤渣水解工艺参数为纤维素酶添加量2%、超声功率200 W、料液比1∶20（g∶mL）、超声时间60 min。在此优化条件下,黄精多糖溶出率达52.5%,水解率为81.3%。黄精水解液与糯米结合发酵的新型黄精黄酒呈淡黄色、清亮透明、酸甜适中,具有黄精中药原有的特殊香味;其中,经检测新型黄精黄酒多糖含量为5.01 mg/mL,远高于传统黄精黄酒、传统黄酒。     

Comparative study of potato protein concentrates extracted using ammonium sulfate and isoelectric precipitation

In this study, effects of NaCl concentrations (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 M) and pH (3.0, 5.0, 7.0, and 8.0) on the physico-chemical and functional properties of potato protein concentrates extracted from potato fruit juice (PFJ) using ammonium sulfate precipitation (ASP) and isoelectric precipitation (IEP) were investigated. The total polyphenol content of potato protein concentrates extracted by IEP (IEPP) was 2.5 times of that of potato protein concentrates extracted by ASP (ASPP), which resulted in the color of IEPP darker than that of ASPP. More protein fractions (74, 62, and 35 kDa) were found in IEPP compared to ASPP. ASPP exhibited higher solubility than IEPP. The emulsifying properties of ASPP and IEPP increased along with the increasing NaCl concentration. ASPP and IEPP showed the lowest emulsifying properties and foaming ability at pH 5.0. While the foaming stability of ASPP and IEPP achieved the maximum and minimum at pH 5.0, respectively. Two endothermic peaks were observed in ASPP at pH 3.0, 8.0, and higher NaCl concentration (≥0.6 M), while more than two endothermic peaks were observed in IEPP at all NaCl concentrations (0.2–1.0 M) and pH values (3.0, 5.0, 7.0, and 8.0). The glutamic acid concentration of ASPP and aspartic acid concentration of IEPP were the highest, while histidine was the lowest according to the amino acid profile of both ASPP and IEPP. In terms of an essential amino acid index with respect to a reference protein of FAO/WHO, the nutritional values of IEPP were higher than those of ASPP.     

美藤果蛋白的功能性质研究

以美藤果饼为原料,采用碱提酸沉法制备美藤果蛋白,研究pH、温度、NaCl浓度和蔗糖浓度对美藤果蛋白功能性质的影响。结果表明:当pH为5时,美藤果蛋白的溶解度、乳化性能和起泡性均最小;随着温度的升高,美藤果蛋白的溶解度、持水性、持油性呈先增大后减小的趋势;加入适量NaCl可增大美藤果蛋白的溶解度、乳化性能和起泡性能;加入蔗糖使美藤果蛋白的起泡性降低,而加入适量的蔗糖可增大美藤果蛋白的乳化性能。pH、温度、NaCl浓度和蔗糖浓度对美藤果蛋白的功能性质有一定影响,可通过改变上述条件以获得良好加工性质的美藤果蛋白产品。     

Functional Properties of Pork Liver Protein Fractions

The functional (emulsifying, gelling and foaming) properties of liver protein fractions as well as their molecular weight distribution and surface hydrophobicity were investigated and compared to commercial proteins. Two protein fractions were characterized: water soluble (WSLP) and WSLP combined with salt soluble liver proteins (W?+?SSLP). The effect of salt concentrations was also investigated (0, 1.8 and 3.4 % NaCl). Both WSLP and W?+?SSLP displayed good emulsifying properties and foam stability. However, their gelling properties were rather poor. An increase in salt concentration decreased the emulsifying properties of WSLP while the effect on W?+?SSLP was less pronounced. Addition of 1.8 % NaCl increased foaming ability of WSLP and W?+?SSLP while foam stability was not affected. Further increase of NaCl (3.4 %) decreased both foaming ability and foam stability and is probably attributed to refolding of the protein molecules because of the higher level of hydrophobic groups with 3.4 % NaCl. Gel forming ability of WSLP and W?+?SSLP containing 0 % was higher compared to high salt concentrations. However, higher salt concentrations shifted onset gelation temperature of WSLP and W?+?SSLP to lower temperatures probably due to partial unfolding of the proteins as indicated by an increase of the surface hydrophobicity.     

高固形物浓度对大豆分离蛋白酸性蛋白酶酶解产物功能特性的影响

本文系统研究了提高固形物浓度对酸性蛋白酶酶法改性大豆分离蛋白分子量分布、氮溶解指数、分散稳定性、持水力、乳化性、起泡性和泡沫稳定性的影响。结果表明:大豆分离蛋白经过酸性蛋白酶控制酶解制备的改性大豆分离蛋白,其产物氮溶解指数、起泡性均有明显提高,分散稳定性略有提高;但持水力、乳化性、泡沫稳定性有所降低。在相同水解度下,随着酶解体系中固形物浓度的提高,改性大豆分离蛋白的分散稳定性、持水力、乳化活性均呈上升趋势,酶解产物中分子量小于10 kDa的肽段以及氮溶解指数呈下降趋势。当水解度小于8%时,低浓度酶解产物起泡性高于高浓度酶解产物,而水解度超过8%时,高浓度酶解产物起泡性大体高于低浓度酶解产物。     

有限酶解对谷朊粉功能性质的影响

为了改善谷朊粉在水溶液中的分散特性,又保留其蛋白质大分子的功能性质,利用碱性蛋白酶对谷朊粉进行了有限水解,研究了谷朊粉的有限酶解条件对酶解物全成分的分散特性、乳化性、发泡性等功能性质以及水解度的影响。结果表明,酶解后谷朊粉在水中的分散性大大提高,而乳化能力和起泡特性则依底物浓度、酶解温度、加酶量和反应时间等因素发生不同的变化。综合评价结果可知,在谷朊粉浓度0.30 g/mL、酶解温度50℃、酶对底物的质量分数为0.75%、反应时间20 min条件下所得酶解物具有较好的功能特性,分散性为0.962,乳化能力为84.3 mL油/g蛋白,起泡性为52 mL。