利用转谷氨酰胺酶提高谷朊粉乳化性研究

转谷氨酰胺酶是一种催化蛋白质分子交联酶类,利用其对谷朊粉乳化性进行改良,研究酶浓度、底物浓度、pH值、反应时间、反应温度对谷朊粉乳化活性和乳化稳定性影响;在此基础上通过正交实验,探索转谷氨酰胺酶酶解谷朊粉提高乳化性最佳反应条件。分析发现五个因素对谷朊粉乳化性影响由强到弱顺序为:pH值、谷朊粉浓度、温度、时间和酶浓度。最佳酶解条件为:谷朊粉浓度为6.0%,酶浓度1.0%,反应时间为1.0h,pH值为5.0,反应温度为45℃;此时谷朊粉乳化活性为84.9%,乳化稳定性为85.7%,比酶解前谷朊粉乳化性有明显提高。     

木瓜蛋白酶改性对大豆分离蛋白乳化性能的影响

研究了木瓜蛋白酶改善大豆分离蛋白的乳化性能,分析了不同底物浓度、酶质量分数、酶解时间对其乳化活性和乳化稳定性的影响,通过正交实验优化了大豆分离蛋白的酶解条件,即:底物浓度为6%,酶质量分数为0.15%,酶解时间为0.5 h,在该条件下大豆分离蛋白溶液的乳化活性和乳化稳定性分别提高了20%和18%。其中底物浓度是最重要的影响因素,酶质量分数次之,酶解时间影响最小。     

2种蛋白酶酶解曲拉干酪素条件优化及抗氧化性比较

以曲拉干酪素为原料、水解度为指标,在酶解时间、酶解温度、pH值、曲拉干酪素质量浓度、酶添加量单因素试验基础上,采用响应面试验对碱性蛋白酶和胰蛋白酶酶解工艺条件进行优化,并对2 种酶解液的1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl,DPPH）自由基、超氧阴离子自由基、羟自由基清除率,Fe2＋、Cu2＋螯合能力和还原力等抗氧化性指标进行比较。结果表明,碱性蛋白酶和胰蛋白酶分别在酶解时间3.8、2.5 h,酶解温度49.8、47.8 ℃,曲拉干酪素质量浓度60、35 g/L,pH 8.5、7.5,酶添加量140、2 900 U/g时水解度最大,为24.25%和13.57%。碱性蛋白酶解液超氧阴离子自由基清除率、Fe2＋螯合能力显著低于胰蛋白酶解液（P＜0.01）;羟自由基清除能力高于胰蛋白酶解液（P＞0.05）;2 种蛋白酶酶解液在酶解液质量浓度1～5 mg/mL时,Cu2＋螯合能力、DPPH自由基清除率和还原力随质量浓度均呈上升趋势,Cu2＋螯合能力低于Fe2＋螯合能力（P＞0.05）,DPPH自由基清除率和还原力二者差异显著（P＜0.01）。2 种蛋白酶对酶解物抗氧化性指标影响不同,碱性蛋白酶酶解物抗氧化性相对较优。     

酶解产物浓度和油相体积分数对甘薯蛋白酶解产物乳化特性的影响

本文研究了酶解产物浓度(0.10%、0.25%、0.50%、0.75%和1.00%,m/V)和油相体积分数(5%、15%、25%、35%和45%,V/V)对超高压下酶解制得甘薯蛋白酶解产物乳化液显微结构、乳化颗粒平均粒径(d4,3)、乳化活性指数(EAI)、乳化稳定性指数(ESI)和流变学性质的影响。当酶解产物浓度较低和油相体积分数较高时,乳化液的乳化颗粒均一细小。增加甘薯蛋白酶解产物浓度会使其乳化液的d4,3、EAI和ESI均逐渐降低;相反,增加油相体积分数会使乳化液的d4,3逐渐减小,EAI逐渐增大,而ESI则先降低后增加(p0.05)。在酶解产物浓度低和油相体积分数高时,乳化液的初始表观粘度较大,且在1~100 s-1的剪切速率范围内均表现出了剪切变稀现象。酶解产物浓度和油相体积分数与乳化液的d4,3、EAI、ESI和流变学性质密切相关,是影响甘薯蛋白酶解产物乳化特性的重要因素。     

木瓜蛋白酶提高谷朊粉乳化性的研究

利用木瓜蛋白酶对谷朊粉乳化性进行改良,研究了酶浓度、底物浓度、pH值、反应时间、反应温度对谷朊粉乳化活性和乳化稳定性的影响,在此基础上通过正交实验,探索木瓜蛋白酶水解谷朊粉提高乳化性的最佳反应条件。分析发现五个因素对谷朊粉乳化性的影响由强到弱的顺序为:谷朊粉浓度、酶浓度、温度、时间和pH值。最佳水解条件为:谷朊粉质量分数11.0%,酶浓度25μl/g谷朊粉,反应时间为2.0 h,pH值7.0,反应温度55℃;此时谷朊粉的水解度3.5%,乳化活性72.4%,乳化稳定性75.5%,比水解前乳化性有明显提高。     

酶改性大豆磷脂乳化稳定性比较

大豆浓缩磷脂、酶改性大豆浓缩磷脂、酶改性大豆粉末磷脂作为乳化剂经均质制备乳化液(油/水=1∶1),调乳化液pH值分别为(3、5、7、9),常温下4h、80℃保温4h、分别添加0.1%NaCl和0.05%CaCl2,常温下放置4h后比较各乳化液的稳定性。添加大豆浓缩磷脂的乳化液受环境影响较大,在碱性或酸性较强条件下稳定性差。而添加酶改性大豆浓缩磷脂和酶改性粉末大豆磷脂乳化液在pH值5￣9下都保持良好的乳化稳定性,在pH值3时亦保持较好的乳化稳定性。在温度80℃条件下,添加酶改性大豆浓缩磷脂和酶改性粉末大豆磷脂,在不同pH值时,乳化能力和乳化稳定性明显好于浓缩大豆磷脂。添加酶改性大豆浓缩磷脂和酶改性粉末大豆磷脂的乳化液,在较高的离子强度下,保持有良好的乳化稳定性。而高离子强度对大豆浓缩磷脂的乳化性影响非常大,尤其在添加CaCl2的情况下,大豆浓缩磷脂几乎失去了乳化能力。在几种条件下,添加酶改性粉末大豆磷脂的乳化液稳定性最好。     

草鱼盐溶蛋白乳化性的研究

在鱼糜制品中,鱼盐溶蛋白(SSP)的乳化特性决定着产品的均匀性和稳定性.首先采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法(SDS-PAGE)测定了草鱼SSP主要成分的分子质量.再采用单因素和响应面实验设计研究了pH、离子强度、油水相体积比对草鱼SSP乳化特性的影响 结果表明:SSP中肌球蛋白的重链、两条轻链和肌动蛋白的分子质量分别为200、30、23、40ku.pH和离子强度是影响SSP乳化能力的极显著因素;当pH为7.94,离子强度为0.7,油水相体积比为1∶7时,乳化活性指数(EAI)达到最大值,为45.78m2/g pH是影响乳化稳定性的显著因素;当pH7.3,离子强度0.58,油水相体积比1∶5时,SSP的乳化稳定指数(ESI)达到最大值0.812综合分析乳化特性指标,得出草鱼盐溶蛋白乳化性的最佳条件为:pH7.5,离子强度0.6,油水相体积比为1∶7.     

预乳化鸡皮对鸡肉香肠品质的影响

以添加鸡皮为对照组（C0,鸡皮添加量30%（质量分数,下同））,添加预乳化鸡皮为处理组,即T1组（鸡皮20%＋预乳化鸡皮10%）、T2组（鸡皮15%＋预乳化鸡皮15%）、T3组（鸡皮10%＋预乳化鸡皮20%）和T4组（预乳化鸡皮30%）,研究预乳化鸡皮对鸡肉香肠品质特性的影响。测定的品质特性指标包括近似组成、蒸煮损失、乳化稳定性、pH值、表观黏度、色泽、质构特性和感官特性。结果表明：随着鸡皮与预乳化鸡皮添加比例的变化,鸡肉香肠的水分含量、脂肪含量、蒸煮损失、乳化稳定性、亮度、质构特性、表观黏度和整体可接受性等指标均有所改变。T2组的水分含量最高（P＜0.05）,C0和T4组的水分含量最低（P＜0.05）;C0组的脂肪含量高于各处理组（P＜0.05）;T2组的蒸煮损失、总可表达流体和脂肪分离比例、硬度、弹性和黏聚性具有最低值（P＜0.05）;各处理组的总体可接受性评分均显著高于对照组（P＜0.05）。预乳化鸡皮的添加可改善鸡肉香肠的品质特性,其中鸡皮与预乳化鸡皮的最适宜添加比例为1∶1。     

酶解大豆分离蛋白-磷脂复合乳液的制备及稳定性分析

为找到一种具有胃保护作用的天然载体,通过胃蛋白酶水解大豆分离蛋白,使大豆分离蛋白改性,建立稳定的酶解大豆分离蛋白-磷脂复合乳液体系。通过显微观察、粒径及电位测定、乳液乳化活性指数、乳化稳定性指数和乳层析指数计算,采用单因素试验、正交试验确定pH 2.0和pH 7.0时的酶解大豆分离蛋白-磷脂复合乳液的最适配比。结果表明:大豆分离蛋白酶解120 min后酶解完全;随着酶解大豆分离蛋白质量浓度的增加,酶解大豆分离蛋白-磷脂复合乳液的稳定性先增加后不变;当磷脂添加量在0.001 0 g/mL时,酶解大豆分离蛋白-磷脂复合乳液的稳定性最大;随着油相体积分数的增加,酶解大豆分离蛋白-磷脂复合乳液的稳定性先增加后不变;正交试验得到,pH 2.0条件下酶解大豆分离蛋白质量浓度0.020 0 g/mL、磷脂添加量0.000 5 g/mL、油相体积分数10%时,酶解大豆分离蛋白-磷脂复合乳液在pH 2.0时最稳定。     

变性脱脂豆粕酶解物的特性研究

为探讨变性脱脂豆粕在胰蛋白酶作用下的水解特性及酶解物的特性,选用国产胰蛋白酶为水解酶对变性豆粕进行水解。研究了变性豆粕中多肽溶出率随温度、pH值、时间、底物浓度及酶用量的变化规律。用正交实验法找出水解变性豆粕的最佳实验条件,并对脱脂豆粕酶解物的性质进行初步研究。结果表明:胰蛋白酶水解变性豆粕的最佳条件为:温度50℃、时间6h、底物质量分数5%、用酶量10000U/g、pH值8.0。在最佳酶解条件下的多肽溶出率为69.34%。脱脂豆粕蛋白酶解物的溶解度比大豆分离蛋白有很大提高,粘度明显低于大豆分离蛋白。此外脱脂豆粕蛋白酶解物有一定的乳化性和乳化稳定性。     

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.     

大豆种子萌发后油脂体乳液稳定性的研究

以大豆为原料,大豆种子经萌发处理后的油脂体乳液为研究对象,通过测量乳化稳定性、过氧化值、硫代巴比妥酸值（TBARS值）及酸价等指标,比较了大豆种子不同萌发时间油脂体乳液的稳定性,研究了不同处理条件（NaCl浓度、pH、贮藏温度）对大豆种子萌发后油脂体乳液稳定性的影响。实验结果表明,大豆种子萌发后油脂体提取率逐渐降低,20 h（12.36%±0.21%）至27 h（10.89%±0.28%）油脂体提取率呈逐渐下降趋势,且27 h后提取率下降显著（P<0.05）。室温下贮藏14 d样品出现不同程度的絮凝。不同萌发时间油脂体乳液稳定性也不同,27 h表面疏水性（99.78±0.88）最大,且乳化稳定性（23.49±0.39）最好。经不同NaCl浓度、pH、贮藏温度处理后,随NaCl浓度的增加,萌发后的大豆油脂体乳液乳化活性无显著变化（P>0.05）,乳化稳定性在NaCl浓度为0~150 mmol/L时呈下降趋势,大于150 mmol/L时无显著变化,150与200 mmol/L时分别为（4.75±0.12）和（4.74±0.14）min,但过氧化值在贮藏0~6 d时显著增加（P<0.05）;pH越高,萌发大豆油脂体乳液的ζ-电势及乳化活性越小,pH为4时乳化活性为（19.13±0.23）m2/g,过氧化值和TBARS值变化显著（P<0.05）;贮藏温度上升,萌发大豆油脂体乳液过氧化值升高,酸价无显著性变化（P>0.05）。不同萌发时间大豆种子油脂体乳液稳定性均存在差异,且萌发27 h后的大豆油脂体较其他萌发时间更稳定。NaCl浓度和pH都对萌发大豆油脂体乳液稳定性有较大影响,且贮藏温度对其影响相对较小。可为今后萌发大豆油脂体的应用提供理论基础。     

Emulsifying and foaming capacity and emulsion and foam stability of sesame protein concentrates

This study examined the effects of oil concentration and pH on the emulsifying and foaming characteristics of sesame protein concentrate (SESPC). SESPC was obtained through a simplified process, and its properties were compared with those of a commercial soybean concentrate (SOYPC). The simplified process did not affect the functional characteristics of SESPC, which were often similar or superior to those of the SOYPC. The maximum emulsifying capacity of SESPC was 38% at an acidic and alkaline pH, while the maximum emulsifying capacity of SOYPC was 44% at the same pH. Emulsifying capacity increased significantly as oil concentration increased; in SESPC, this capacity increased from 7.8 to 60.0%, while in SOYPC it increased from 7.6 to 68.2%. The emulsion stability of SESPC was greater at an acidic pH (51%) than at an alkaline pH (45%); it was also higher than the emulsion stability of SOYPC. The maximum emulsion stability of SESPC (96%) was obtained at a sample concentration greater than 55 g L^− 1 and oil concentration lees than 550 g L^− 1 oil. Minimum (118.3%) and maximum (240%) levels of SESPC foaming capacity were higher than those obtained for SOYPC (92% as maximum). These findings show that SESPC may have potential use as raw matter in the food industry. At an extreme pH, SESPC continued to have important functional characteristics like emulsion stability, oil absorption and foaming capacity.     

花生分离蛋白磷酸化改性研究

采用响应面优化法对花生分离蛋白进行磷酸化改性,以氮溶解指数(NSI)为指标得出花生分离蛋白磷酸化改性的最佳条件为三聚磷酸钠添加量7.77%、花生分离蛋白质量分数6.38%、反应温度44.85℃、反应体系pH8.24、反应时间5.68h。得到的花生改性蛋白NSI 最大值为77.74%。改性后,花生分离蛋白的吸油性、吸水性、持水性、乳化性、乳化稳定性、泡沫稳定性都有不同程度的提高。     

Physicochemical and Functional Properties of Tea Protein

Tea protein has received much attention due to its potential health functions. This article studied the molecular weight, foaming capacity, foam stability, emulsifying capacity, emulsion stability, and oil absorption of tea protein prepared from tea residue by alkali extraction. The results showed that tea protein contained two components with different molecular weights (1.26 × 10⁶ ± 1.3 × 10⁴ and 2.4 × 10⁴ ± 1.1 × 10³). The content of the lower molecular component in tea protein was higher than the higher molecular one. When the concentration of tea protein was 4 mg/mL, its sparkling ability was satisfied, while the foaming capacity and foam stability was the best, respectively, at the conditions of pH 9 and 7. The emulsifying capacity was 62 ± 2% as well as 99 ± 1% of emulsion stability, and oil absorption was 170 ± 7%.     

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。     

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。     

加工工艺对荞麦蛋白功能特性的影响

探讨了加工工艺对荞麦蛋白(BWP)功能特性的影响。pH＜5．0和 pH＞6．0时,喷雾干燥制备的荞麦蛋白(SBWP)的溶解度高于商品大豆分离蛋白(SPI)(P＜0．05)。pH＜7．0时,超声协助提取荞麦蛋白(U- BWP)的溶解度较搅拌提取荞麦蛋白(M-BWP)和脱脂、超声协助提取荞麦蛋白(DU-BWP)好；pH＞7．0时,结果相反。总体来说,BWP 持油能力较 SPI 强,且冷冻干燥制备的荞麦蛋白(F-BWP)的持水、持油能力强于 S-BWP (P＜0．05)。BWP 的乳化活性与其溶解度呈正相关。pH 4．0～5．0时,BWP 的乳化活性指数(EAI)最小而乳化稳定性(ES)最高。脱脂处理明显提高了 BWP 的 EAI 和 ES。     

三聚磷酸钠对猪肉肌原纤维蛋白功能特性的影响

以猪肉肌原纤维蛋白（myofibril protein,MP）为研究对象,探讨不同质量浓度三聚磷酸钠（sodium tripolyphosphate,STP）的添加对MP乳化性、乳化稳定性、起泡性等7 个功能特性指标的影响,并进行相关性分析。结果表明：随着STP质量浓度升高,MP的乳化性、乳化稳定性、起泡性、起泡稳定性、凝胶强度和凝胶保水性均呈上升趋势,表面疏水性呈下降趋势;MP的起泡性和凝胶强度在STP质量浓度为0.3 g/100 mL时最大,乳化性、表面疏水性和凝胶保水性在STP质量浓度为0.4 g/100 mL时效果最佳;MP的起泡性、起泡稳定性和乳化性呈极显著正相关（P＜0.01）,乳化性与乳化稳定性呈显著正相关（P＜0.05）,乳化性、乳化稳定性、起泡性、起泡稳定性与表面疏水性呈极显著负相关（P＜0.01）,与凝胶保水性呈极显著正相关（P＜0.01）,表面疏水性与凝胶保水性呈极显著负相关（P＜0.01）,表面疏水性与凝胶强度呈极显著正相关（P＜0.01）。STP可以增强MP的功能特性,其质量浓度为0.3～0.4 g/100 mL时效果最佳。改善乳化性、起泡性和表面疏水性等界面性质可以增强MP的凝胶特性。     

Effect of acetylation and succinylation on solubility profile, water absorption capacity, oil absorption capacity and emulsifying properties of mucuna bean (Mucuna pruriens) protein concentrate

Mucuna protein concentrate was acylated with succinic and acetic anhydride. The effects of acylation on solubility, water absorption capacity, oil absorption capacity and emulsifying properties were investigated. The pH-dependent solubility profile of unmodified mucuna protein concentrate (U-mpc) showed a decrease in solubility with decrease in pH and resolubilisation at pH values acidic to isoelectric pH (pH 4). Apart from pH 2, both acetylated mucuna protein concentrates (A-mpc) and succinylated mucuna protein concentrate (S-mpc) had improved solubility over the unmodified derivative. Acylation increased the water absorption capacity (WAC) at all levels of ionic strength (0.1-1.0 M). WAC of the protein samples increased with increase in ionic strength up to 0.2 M after which a decline occurred with increase in ionic strength from 0.4-1.0 M. When protein solutions were prepared in salts of various ions, increase in WAC followed the Hofmeister series in the order: NaSCN < NaClO4 < NaI < NaBr < NaCl < Na2SO. Acetylation improved the oil absorption capacity while the lipophilic tendency reduced the following succinylation. Emulsifying capacity increased with increase in concentration up to 2, 4 and 5% w/v for U-mpc, A-mpc and S-mpc, respectively, after which an increase in concentration reduced the emulsifying capacity. Both acetylation and succinylation significantly (P < 0.05) improved the emulsifying capacity at pH 4-10. Initial increase in ionic strength up to 0.4 M for U-mpc and 0.4 M for A-mpc and S-mpc increased the emulsion capacity progressively. Further increase in ionic strength reduced emulsion capacity (EC). Contrary to the effect of various salts on WAC, increase in EC generally follows the series Na2SO4 < NaCl < NaBr < NaI < NaClO4 < NaSCN. At all levels of ionic strength studied, S-mpc had a better emulsifying activity (EA) than both A-mpc and U-mpc. EA and emulsifying stability (ES) were pH-dependent. Maximum EA and ES were recorded at pH 10. ES of protein derivatives were higher than those of U-mpc in the range of pH 4-10 but lower at pH 2. Studies revealed that both A-mpc and S-mpc had better ES and EA than the unmodified derivative when protein solutions were prepared in salts of various anions.