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。     

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。     

苦杏仁蛋白质功能特性的研究

目的研究苦杏仁蛋白加工特性,为其应用提供理论依据。方法采用单因素变量法测定p H值、温度、氯化钠浓度、蛋白质浓度等因素对杏仁蛋白加工特性的影响。结果在蛋白等电点附近时,杏仁蛋白的持水性、起泡性、乳化性及乳化稳定性均最差;在25~35℃范围内,提高温度可促进杏仁蛋白各项功能特性的提高,但超出55℃后,各项功能特性降低;低浓度的氯化钠可促进蛋白质起泡性及泡沫稳定性、乳化性及乳化稳定性的提高,高浓度氯化钠(0.8 mol/L)对蛋白功能特性提高具有抑制作用;蛋白质的起泡性及泡沫稳定性、乳化性及乳化稳定性随其浓度增加略有升高。结论 p H值、温度、氯化钠浓度、蛋白质浓度等因素对蛋白特性影响显著,在将杏仁蛋白应用于食品中时应考虑这些因素的影响。     

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。     

丝素功能性质的研究

丝素蛋白的乳化性和起泡性受浓度、pH值和氯化钠浓度的影响。当丝素蛋白的浓度、pH值在某个范围时,乳化能力和乳化稳定性最好,但随氯化钠含量的增加而降低。丝素蛋白的pH值在为某个范围时起泡性最好,且起泡性随浓度及氯化钠浓度的提高而提高。     

温度和pH对山核桃蛋白功能性质的影响研究

以山核桃粕为原料,通过碱溶酸沉法提取山核桃蛋白,探讨温度和p H对其功能性质——溶解性、持水性、吸油性、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:当p H为5.0时,山核桃蛋白在水中的溶解性最小,乳化性及乳化稳定性、起泡性及泡沫稳定性最差;当p H大于5.0时,山核桃蛋白的溶解性、乳化性及乳化稳定性、起泡性及泡沫稳定性随p H的增加而增加;当温度为50℃时,山核桃蛋白的持水性最大、吸油性最低;当温度高于50℃时,山核桃蛋白的持水性随温度升高而降低,而吸油性随温度升高而增加。     

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。     

杏鲍菇蛋白质功能特性研究

为了解杏鲍菇蛋白质的功能特性,试验选择离子强度、温度、pH和蔗糖浓度等因素,研究其对杏鲍菇蛋白质持水性、持油性、起泡性、起泡稳定性、乳化性及乳化稳定性等的影响。结果表明,离子强度对杏鲍菇蛋白的持水性、持油性、起泡性及乳化性都会随着离子强度的增加而降低,而对起泡稳定性的影响是先增加后减少再增加,对乳化稳定性的影响是先增大后减少,浓度为1 g/L时稳定性最好;温度和蔗糖浓度对持水性、持油性、起泡性及乳化性的影响是先增大后减少,而温度对起泡稳定性的影响是先增大后减少,蔗糖浓度对起泡稳定性及乳化稳定性的影响是先减少后增大,糖浓度分别为2 g/L和1.5 g/L时稳定性最差;pH值对蛋白质的持水性、持油性、起泡性及乳化性的影响都是在等电点附近最低,在等电点附近的两侧都会呈现上升的趋势,而其对起泡性稳定性和乳化性稳定性的影响则相反。说明离子强度、温度、蔗糖浓度和pH对蛋白质的功能性质具有一定的影响,因此,在加工过程中,需要根据加工产品要求控制条件。     

卵白蛋白起泡性影响因素研究

为研究影响卵白蛋白起泡性的因素,考察氯化钠、大豆分离蛋白、蔗糖、卡拉胶、温度和pH值对卵白蛋白起泡特性的影响。结果表明,在一定浓度范围内,NaCl、大豆分离蛋白均可改善卵白蛋白起泡力,蔗糖、卡拉胶均可改善卵白蛋白的泡沫稳定性。在40~50℃温度范围内可提高卵白蛋白起泡性;卵白蛋白在等电点附近起泡性差,在pH 7.0~8.0时起泡性较理想。     

春油菜菜籽蛋白的提取工艺优化及性质研究

为了提高菜籽粕的附加值和利用率,为人类提供优质的食品蛋白源。本研究以热榨春油菜菜籽粕为原料,采用碱溶酸沉法提取菜籽蛋白,并对其功能性质进行了研究。结果表明：在pH值12.0、提取时间50min、提取温度40℃、料液比1∶40、提取次数为3次的条件下菜籽蛋白的提取率达到56.35%。其中pH值对菜籽蛋白提取率的影响最大,料液比和提取次数次之,提取温度对菜籽蛋白提取率的影响最小,且pH值对菜籽蛋白提取率的影响达极显著水平;菜籽蛋白的pH值-溶解度曲线和持水性基本符合＂V＂字形,在等电点（pH值4）时最低;在中性偏碱环境中菜籽蛋白的起泡性及泡沫稳定性优良;添加蔗糖对菜籽蛋白的乳化性和乳化稳定性的影响比较小,蔗糖浓度为2%～3%时乳化性及其乳化稳定性最好。     

Comparative study on physicochemical and functional properties of egg powders from Japanese quail and white Leghorn chicken

Physicochemical and functional properties of freeze-dried egg powders (egg white, egg yolk, and whole egg) from Japanese quail and white Leghorn chicken were studied comparatively. All egg powders had protein content in the range of 91.13–97.03 g/100 g powder. The quail egg powder had higher mineral and essential amino acid contents, but lower fat content as compared to chicken egg powders (P < 0.05). Moreover, egg white powder from both quail and chicken presented higher total amino acids content than corresponding whole egg and egg yolk powders, respectively. Fourier transform infrared spectroscopic study revealed that β-sheet is the major secondary structure of all egg powders. Based on differential scanning calorimetry analysis, quail egg powders showed slightly lower denaturation temperatures than corresponding chicken egg powders (P < 0.05). Sodium dodecyl sulfate–polyacrylamide gel electrophoresis study showed the slight difference in protein patterns of corresponding quail and chicken egg powders. The quail egg powders presented higher protein solubility than corresponding chicken egg powders at all pH tested. Furthermore, quail egg powders exhibited higher emulsion activity index and emulsion stability index with higher foam expansion and stability than the corresponding chicken egg powders. Therefore, Japanese quail egg powders could be used as an alternative to white Leghorn chicken egg in the preparation of foods and diets that require high protein content with positive health benefits.     

TEMPERATURES IN EGG PRODUCT FOAMS DURING VAT PASTEURIZATION

SUMMARY– Most egg products are pasteurized in continuous-flow equipment, but small quantities are more economically processed in a vat pasteurizer. By insulating itself, the surface foam in the vat process may be below pasteurization temperature for a significant part of the holding time and salmonellae in the foam may survive. Using a 100-gal vat, we generated foams on 5 egg products and measured foam temperatures during pasteurization. Maximum jacket temperature was held to 160°F and no product burn-on was observed in the vat. All products were held above their respective pasteurization temperatures for 30 min. The minimum temperature of a 6.5-in. liquid whole egg foam was below pasteurization temperature for 11 min after start of pasteurization. The delayed heating effect of a 1-in. foam on sugared yolk (10% sucrose by weight) was 13 min. Yolk and salted yolk (10% salt by weight) foams were below liquid temperature during heating; however, in both cases liquid and foam reached pasteurization temperature simultaneously. Minimum temperature of plain egg white foam (pH 9.0) did not reach pasteurization temperature during the holding period. In vat pasteurization, the holding time begins when the liquid reaches pasteurization temperature, and the holding time should be long enough for both foam heating and pasteurization of foam. Except for egg white, about 15 min was required to heat foam to pasteurization temperature. Adding 15 min for pasteurization of the foam yielded a total holding time of 30 min, with the temperature of pasteurization established on the basis of the 15-min holding time for the foam as follows: liquid whole egg, 133°F; yolk and yolk blends, 135°F; sugared and salted yolk, 139°F. With egg white, foam heating times were in excess of 30 min, and vat pasteurization, with a holding time of 30 min, was not effective.     

芝麻蛋白发泡性、持水力的理论研究

本文比较系统地研究了芝麻蛋白的发泡性和持水力等功能特性，探讨了不同蛋白质浓度、ｐＨ值、离子强度和温度因素对芝麻蛋白发泡性和持水力的影响，进行了芝麻蛋白功能特性的变化规律的研究，从理论上解释了芝麻蛋白的发泡性以及持水力的变化特点，为芝麻蛋白在食品工业上的应用提供了依据。     

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。     

胃蛋白酶水解大米蛋白的研究

采用胃蛋白酶对大米蛋白进行水解以改善其功能性质。结果表明,酶添加量7U/g(以蛋白质干基计)、pH1.5、时间5h、温度30℃时,胃蛋白酶对大米蛋白溶解性有较好的改善作用。水解后大米蛋白的乳化稳定性与乳化性分别为33.28min、0.456,高于大豆蛋白和鸡蛋清蛋白;起泡性和起泡稳定性比未经过任何处理的大米蛋白分别提高了25.0%、82.4%;持水性和持油性为2.80、3.30g/g,是未经处理的大米蛋白的2.09、2.92 倍。     

杏鲍菇谷蛋白理化性质及功能特性研究

以杏鲍菇为原料,采用Osborne法提取出杏鲍菇谷蛋白,并对其功能特性及理化性质进行研究。结果表明:杏鲍菇谷蛋白的等电点为4.3,谷蛋白的亚基分子量分布在30.28、25.39 kDa附近,总巯基、游离巯基、二硫键含量分别为67.06、28.90、14.35μmol/g,二级结构占比为α-螺旋31.41%、β-折叠55.15%、β-转角13.45%,变性温度为73.59℃,必需氨基酸占比为40.77%。杏鲍菇谷蛋白随着离子强度的增加,溶解度(solubility,S)及乳化稳定性(emulsification stability,ES)呈先增大后减小的趋势,持水性(water holding capacity,WA)、持油性(oil holding capacity,FA)、起泡性(foam capability,FC)及起泡稳定性(foam stability,FS)、乳化性(emulsion capability,EC)则呈相反趋势;随着温度的升高,S、WA、FC及FS、EC及ES都呈先增加后减小的趋势,FA则呈相反趋势;随着pH值增大,FS和ES呈先增大后减小的趋势,S、WA、FA、FC、EC则呈相反趋势;随着蔗糖浓度的增大,S、WA、FA、FC及EC都呈先增加后降低的趋势,FS及ES则呈相反趋势。     

限制性酶解结合大孔树脂吸附对葵花籽蛋白色泽及功能特性的影响

以低温脱脂葵花籽粕为原料提取葵花籽蛋白,对其分别进行大孔树脂吸附脱色和限制性酶解结合大孔树脂吸附脱色处理,对比不同处理的葵花籽蛋白白度值、绿原酸含量及功能特性(溶解性、乳化性、乳化稳定性、起泡性、泡沫稳定性、持油性、持水性和凝胶性)的差异。结果表明:限制性酶解10 min结合大孔树脂吸附脱色的葵花籽蛋白白度值(L^*)为86.3,绿原酸含量为0.16 mg/g,溶解性为77.60%,起泡性为20.87%,乳化性为3.44 m²/g,乳化稳定性为118.51 min,均显著优于葵花籽蛋白和大孔树脂吸附脱色葵花籽蛋白(P <0.05),持水性为1.94 mL/g,显著优于葵花籽蛋白,但与大孔树脂吸附脱色葵花籽蛋白相当,持油性和泡沫稳定性分别为4.40 mL/g和69.62%,显著低于葵花籽蛋白和大孔树脂吸附脱色葵花籽蛋白,限制性酶解10 min结合大孔树脂吸附脱色葵花籽蛋白展现出较好的凝胶性。研究表明,经限制性酶解结合大孔树脂吸附脱色后,葵花籽蛋白色泽显著改善,其溶解性、乳化性、起泡性、持水性和凝胶性均显著提高。     

Impact of pH on the interactions between whey and egg white proteins as assessed by the foamability of their mixtures

The impact of protein–protein interactions on foaming properties of mixtures consisting of egg white proteins (EWP) and whey proteins (WP) with total protein content of 60 g/L was examined at pH 5, 7 and 9. The ratio between EWP and WP in the mixtures was varied between 67:33, 50:50 and 33:67 (in %; w/w). The ionic strength was adjusted to that of milk (I = 176 mM). The foamability of the protein products was characterized by the foam capacity, stability and firmness. In addition, the hydrophobicity in the protein solutions was assessed as a measure for the physical behaviour and ability of proteins to adsorb at the air–water interface.The individual egg white proteins and whey proteins each showed the best foaming properties at pH 5 and pH 9, respectively. At pH 9 a synergism was observed in the capacity and stability of the foams from EWP/WP-mixtures. This effect appears to be caused by the electrostatic interactions between egg white and whey proteins which occur in the bulk solution after the pH adjustment prior to the foaming. In contrast, at pH 5 no positive influence of foaming the components in a mixture as well as no indication of intermolecular interactions was found. At pH value near the pI of ovalbumin the protein interactions occur when the proteins have adsorbed at the air–water interface. The protein systems foamed at pH 7 showed intermediate foamability compared to the values obtained at alkaline and acidic pH.     

Use of Mucor miehei lipase to improve functional properties of yolk-contaminated egg whites

Egg yolk contamination of egg whites continues to be a serious problem in the egg industry. The ability of egg whites to form stable and voluminous foams is greatly inhibited by yolk contamination, even at very low levels, between 0.01% and 0.2% w/w yolk in white. Experiments were conducted to determine if Mucor miehei lipase could regenerate the functional properties of yolk-contaminated egg whites. Lipase from M. miehei and colipase from porcine pancreas were added to yolk-contaminated (0.2%, w/w) egg white samples to hydrolyze triglycerides originating from egg yolk. Enzymatic hydrolysis of triacylglycerols was confirmed using thin-layer chromatography. Treatment of yolk-contaminated samples with lipase and colipase yielded significant (P < 0.05) improvements in a number of the functional properties, including the final foam volume, foam capacity, and foaming power. These functional properties showed complete restoration to control levels. However, foam stability and foam drainage levels were not statistically different from yolk-contaminated samples that had not been enzymatically treated. Enzyme-treated yolk-contaminated egg whites were also tested in angel food cakes. Enzyme-treated, yolk-contaminated egg whites performed similarly to non-yolk-contaminated control, and much better than yolk-contaminated sample in angel food cakes. The results show that most negative effects of yolk contamination can be reversed by treatment with Mucor miehei lipase and colipase.     

高压脉冲电场(PEF)对蛋清蛋白功能特性的影响

蛋清蛋白不仅具有重要的营养价值,而且还具有重要的功能特性如乳化性、起泡性等,作为一种重要的蛋白原料,本实验研究了高压脉冲电场对蛋清蛋白功能性质的影响。结果表明:蛋清蛋白的溶解度在脉冲电场强度大于35kV/cm时下降;蛋清蛋白的乳化性、起泡能力、泡沫稳定性及疏水性先随脉冲电场强度增加而增大,但当脉冲电场强度大于30kV/cm后,蛋清蛋白的乳化性、起泡能力、泡沫稳定性及疏水性下降;随着脉冲电场数的增加,蛋清蛋白的溶解度、乳化性、起泡能力、泡沫稳定性及疏水性变化不显著。