芝麻渣蛋白的功能性研究

本实验以芝麻渣为原料,采用碱提、等电点法分离出芝麻蛋白,并对其乳化性、发泡性、持水力、黏度、热凝集性等功能特性进行了比较系统的研究。结果表明：芝麻蛋白具有较好乳化性、发泡性,一定的持水力;pH值对热凝集性的影响较大。     

芝麻蛋白功能性质的研究

本文主要对芝麻蛋白的乳化性、湿润性、吸油性、热凝集性和黏度等功能特性进行了研究,并与大豆分离蛋白、酪蛋白和麻渣蛋白的相关性质进行比较.结果表明:芝麻蛋白具有较好湿润性、吸油性、吸水性,较弱的持水力;pH值对热凝集性和黏度的影响较大.     

血浆蛋白的功能特性及其在食品中的应用

研究了猪血浆蛋白在不同浓度和pH条件下的乳化性、发泡性、发泡稳定性和持水性等功能特性，并将血浆蛋白应用到蛋糕制品中。     

花生蛋白粉功能特性影响因素的研究

研究了花生蛋白粉的功能特性，探讨了不同蛋白浓度、ｐＨ、温度对其溶解性、发泡性、持水性的影响。当ｐＨ在４．２～５．３范围内，为其等电点，此时，花生蛋白粉的溶解性、发泡性、持水性最低，在其两侧随ｐＨ增加或降低，这些特性逐渐增强；当温度超过６０℃时，为花生蛋白溶液大幅度变性的临界温度，其溶解度、持水性下降；随温度升高，发泡性增加，在蛋白浓度为３％时，起泡性最高     

反相微乳法与碱法、酶法制备的茶蛋白功能性质比较研究

本文以绿茶茶渣为原料,采用新兴的反相微乳法提取制备茶渣蛋白,以开发利用茶渣蛋白为目标,对茶渣蛋白的功能特性展开研究,并与碱溶酸沉法、酶法茶蛋白功能性质比较分析。对CTAB-Tween80反相微乳提取制备的茶渣蛋白的功能性质进行研究,结果表明:茶渣蛋白在p H4.0时溶解度最低,溶解度随p H的增加呈现先降低后升高的趋势,其吸油性为2.54 g/g,持水力为1.78 g/g,乳化性为60.27%、乳化稳定性为84.56%,发泡性为68.69%、泡沫稳定性为59.30%。表明反相微乳法制备的茶渣蛋白除了在吸油性、持水力及泡沫稳定性方面与碱溶酸沉法和酶法稍有差异外,乳化性、乳化稳定性及发泡性等均优于碱溶酸沉法和酶法,因而反相微乳法可较好的保持茶渣蛋白的功能特性。     

芝麻蛋白提取液超滤浓缩工艺及其功能特性研究

研究超滤法浓缩芝麻蛋白提取液的工艺条件及芝麻蛋白的主要功能特性。以膜通量为评价指标,通过单因素实验,探讨了超滤压力、温度、p H和时间对芝麻蛋白提取液膜通量的影响,在此基础上通过正交实验确定超滤浓缩的最佳工艺参数。结果表明,超滤浓缩芝麻蛋白提取液的最佳工艺条件为:超滤压力为0.25MPa,提取液p H为10.0,超滤时间为15min。在此条件下获得的芝麻蛋白具有良好的功能特性,其中乳化性和乳化稳定性及发泡性能显著高于等电点沉淀法制备的芝麻蛋白(p0.05)。本研究为芝麻蛋白的深入研究和开发利用提供一定的参考。     

转谷氨酰胺酶聚合改性大豆分离蛋白的功能特性研究

研究了转谷氨酰胺酶(MTGase)聚合改性大豆分离蛋白的持水性、吸油性、溶解性、乳化性、发泡性及凝胶强度等功能特性。结果显示,与大豆分离蛋白相比,MTGase改性的大豆分离蛋白(MSPI)具有更高的凝胶性和乳化稳定性,但其溶解性、持水性、吸油性、起泡性与泡沫稳定性和乳化性明显减弱。     

玉米醇溶蛋白提取工艺及功能性质研究

阐述了玉米醇溶蛋白的提取工艺，并对玉米醇溶蛋白的吸水性、持水力、湿润性、吸油性、乳化性、乳化稳定性、凝胶性和粘度等功能特性进行了测定，并与大豆分离蛋白和酪蛋白的相关性质进行比较，结果表明：玉米醇溶蛋白的吸水性低于大豆分离蛋白，但高于酪蛋白；玉米醇溶蛋白具有较好湿润性、吸油性、凝胶性，较弱的持水力和乳化性，一定的乳化稳定性．粘度随时间增加而增大。     

不同提取方法对茶渣蛋白功能特性的影响

以单枞茶叶为实验材料,研究了单一碱法提取、挤压膨化预处理碱法提取、挤压膨化预处理酶法提取对茶渣蛋白功能特性的影响。结果表明,与单一碱法提取的茶渣蛋白相比较,挤压膨化预处理碱法提取的茶渣蛋白吸水性、持水力、起泡性和乳化性分别提高了25%、43.43%、8.79%、5.57%,吸油性降低了8.67%;挤压膨化预处理酶法提取茶渣蛋白吸水性、持水力、起泡性和乳化性分别提高了34.73%、86.87%、18.01%、12.46%,吸油性降低了18.50%;挤压膨化预处理对茶渣蛋白功能特性有一定的改善作用。     

金属离子和pH值对芝麻饼分离蛋白功能性的影响

研究以压榨芝麻饼为原料,采用碱溶酸沉法制备了芝麻饼分离蛋白,并考察了金属离子和溶液的pH值对芝麻饼分离蛋白功能性的影响.结果表明,芝麻饼蛋白、芝麻蛋白的等电点均在pH 4～6范围内;金属离子和溶液pH值时它们的溶解性、乳化性和持水性均有较大影响;在相同条件下,芝麻饼蛋白的溶解性、乳化性、持水性均弱于芝麻蛋白.     

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。     

pH值碱性偏移结合热处理对米糠蛋白结构和功能性质的影响

研究pH值碱性偏移（pH 11）结合热处理（50、60 ℃）对米糠蛋白结构和功能性质的影响。结果表明,pH值碱性偏移促使米糠蛋白二级结构由有序向无序转化,pH值碱性偏移结合热处理使得米糠蛋白二级结构呈现折叠-去折叠-复折叠的复杂变化,并伴随巯基氧化。pH值碱性偏移促使米糠蛋白展开,随着处理时间的延长,米糠蛋白重新聚集,热处理会加剧聚集程度。pH值碱性偏移使得米糠蛋白持水性、起泡性、泡沫稳定性、乳化性和乳化稳定性显著下降,仅持油性显著改善;随着处理时间的延长,米糠蛋白持水性、起泡性、乳化性和乳化稳定性逐渐上升,其中乳化性上升幅度最大。pH值碱性偏移结合热处理可显著改善米糠蛋白的持水性、起泡性、泡沫稳定性和乳化稳定性,同时也会降低米糠蛋白的持油性和乳化性。     

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。     

High pressure effect on foaming properties of β‐lactoglobulin and dextran sulfate mixture

The foaming behaviour of the β‐lactoglobulin + dextran sulfate (DS) mixture was investigated by recording the small pressure changes in the head space above the collapsing foam in a closed container. The foaming ability was based on the highest pressure obtained from the complete decay of foam. The foam stability was based on the foam decay rate constant of the first‐order kinetic law calculated from the pressure change as a function of time. The foamability and foam stability were also assessed in terms of visual measurements of foam half‐life and initial foam volume. A good correlation was found between foam stability results based on visual measurements and those based on the differential pressure monitoring technique. Foaming was studied at a β‐lactoglobulin/DS weight ratio of 3 with the protein concentration of 0.15 wt.‐% at pH 7.0. The surface tension measurements showed no change in the activity of protein upon addition of DS. Pressure treatment (0–800 MPa) of pure protein solution indicated no change in the foamability and foam stability. Pressure‐treated solutions of β‐lactoglobulin + DS showed an improvement in the foaming ability and a reduction in foam stability suggesting that polysaccharide molecules prevent protein molecules against aggregation.     

High pressure effect on foaming properties of beta-lactoglobulin and dextran sulfate mixture.

The foaming behaviour of the beta-lactoglobulin + dextran sulfate (DS) mixture was investigated by recording the small pressure changes in the head space above the collapsing foam in a closed container. The foaming ability was based on the highest pressure obtained from the complete decay of foam. The foam stability was based on the foam decay rate constant of the first-order kinetic law calculated from the pressure change as a function of time. The foamability and foam stability were also assessed in terms of visual measurements of foam half-life and initial foam volume. A good correlation was found between foam stability results based on visual measurements and those based on the differential pressure monitoring technique. Foaming was studied at a beta-lactoglobulin/DS weight ratio of 3 with the protein concentration of 0.15 wt.-% at pH 7.0. The surface tension measurements showed no change in the activity of protein upon addition of DS. Pressure treatment (0-800 MPa) of pure protein solution indicated no change in the foamability and foam stability. Pressure-treated solutions of beta-lactoglobulin + DS showed an improvement in the foaming ability and a reduction in foam stability suggesting that polysaccharide molecules prevent protein molecules against aggregation.     

Foaming properties of oilseed proteins

Oilseeds are important sources of edible proteins. Their varieties varied in oil and protein content; sesame and rapeseeds had the highest oil content, but soybean and glandless cottonseeds had the highest protein content. Foaming properties of oilseed proteins are important for the domestic market to be used in the preparation of various food products. Whole rapeseed had the highest foam capacity followed by soybean, sunflower, safflower, glandless cottonseed, peanut and finally sesame. The extraction of lipids from oilseeds caused a significant improvement in their foam capacity and foam stability. High positive correlation was found between soluble proteins and foam capacity of oilseeds. The foam capacity was high at pH 7, and decreased below it reaching a minimum at pH 4. The foam stability also varied with pH; being maximum at the isoelectric point and minimum at pH 7. The foam capacity of oilseed protein isolates decreased with the prolongation of heating time at 100 °C.     

Influence of pH Shift on Functional Properties of Protein Isolated of Tilapia (<Emphasis Type="Italic">Oreochromis niloticus</Emphasis>) Muscles and of Soy Protein Isolate

The physicofunctional and chemical properties of acid-aided protein isolate (AcPi), alkaline-aided protein isolate (AlPi) and soy protein isolate (SPI) prepared from tilapia muscle and defatted soy flour as a function of pH and/or NaCl concentration were investigated. Both acid- and alkali-aided processes lead to significant recoveries (P < 0.05) of proteins with substantial reduction of lipids in AlPi (0.81%) and AcPi (0.96%), the lowest for SPI (0.336%) facilitated by the processing method and sample used. There is greater lipid reduction at alkali pH, effective removal of impurities such as bones and scales, indicated by percentage ash (AcPi, 4.53%; AlPi, 3.75% and SPI, 3.51%). No major difference noted in sodium dodecyl sulphate polyacrylamide gel electrophoresis protein bands (14.4–97.4 kDa) possibly representing partial hydrolysis of myosin. Solubility was the highest at pH 3.0 and 11.0 and the lowest at isoelectric point with foam capacity showing similarity at varying pH. The addition of NaCl improved foam stability, possibly due to the increased solubility and surface activity of the soluble protein. On the whole, AcPi, AlPi and SPI manifested lower solubility and foamability at pH 4.0 and 5.0. AlPi exhibited appreciable levels of solubility, emulsion capacity, oil-holding capacity, viscosity and whiteness, whereas SPI had appreciable water-holding capacity. AcPi, AlPi and SPI have excellent relevance for product development based on their functionality.     

不同种类活性短肽的理化与功能特性比较

比较了大米肽、大豆肽、小麦肽、白蛋白肽、花生肽、山药肽、玉米肽、海洋胶原蛋白肽和乳清肽在不同p H值和钠离子强度条件下的乳化活性、乳化稳定性、溶解性、起泡性及泡沫稳定性。结果表明:碱性条件下各活性短肽的乳化活性、乳化稳定性、溶解性、起泡性均优于酸性条件下的,但其泡沫稳定性差异不明显;随着钠离子强度的增强,各活性短肽的起泡性增强,乳化活性、乳化稳定性及溶解性降低,但其泡沫稳定性变化不明显;在相同p H值条件下,乳清肽、玉米肽、大豆肽和花生肽的乳化活性、乳化稳定性、起泡性及泡沫稳定性优于大米肽、小麦肽、白蛋白肽、山药肽和海洋胶原蛋白肽;在相同的钠离子强度条件下,乳清肽、玉米肽、大豆肽、海洋胶原蛋白肽和花生肽的乳化稳定性优于大米肽、小麦肽、白蛋白肽和山药肽,乳清肽和大豆肽的乳化活性、起泡性和泡沫稳定性优于其他7种短肽。不同种类活性短肽上述理化特性差异与其氨基酸组成和分子质量大小密切相关,应根据其特性差异进行选择性应用。     

A comparison of the buttermilk solids functional properties to nonfat dried milk,soy protein isolate,dried egg white,and egg yolk powders

Physicochemical (i.e., sulfhydryl group, protein, and total solubility) as well as functional properties (i.e., water-holding and fat-absorption capacity, foaming and emulsification capacity, and stability) of commercial buttermilk solids (BMS) were compared to nonfat dried milk, soy protein isolate, and dried egg yolk and egg white powders on an equivalent protein basis. BMS showed limited functional properties in water-holding capacity (0.75 g water/g protein) and fat-absorption capacity (1.2 g of oil/g of protein), and foaming capacity (0.5 ml of foam/ml of solution) and stability. However, emulsifying capacity and stability of BMS was not significantly different from other dried protein powders. Results indicated that 0.9 g of protein (approximately 0.45%, wt/vol, concentration) from BMS was needed to emulsify a maximum oil concentration of 50% in water at temperatures up to 50 degrees C. Denaturation of protein, quantified by free sulfhydryl groups, was a critical factor affecting the functionality of BMS and all other protein powders tested. The milk fat globule membrane present in BMS did not enhance either emulsifying capacity or stability.     

Solubility and functional properties of sesame seed proteins as influenced by pH and/or salt concentration

The protein content, solubility and functional properties of a total protein isolate prepared from sesame seeds (Kenana 1 cultivar) as a function of pH and/or NaCl concentration were investigated. The protein content of the seed was found to be 47.70%. The minimum protein solubility was at pH 5 and the maximum was at pH 3. The emulsifying capacity, activity and emulsion stability as well as foaming capacity and foam stability were greatly affected by pH levels and salt concentrations. Lower values were observed at acidic pH and high salt concentration. The protein isolate was highly viscous and dispersable at pH 9 with water holding capacity of 2.10 ml H₂O/g protein, oil holding capacity of 1.50 ml oil/g protein and bulk density of 0.71 gm/ml.