Enhancement of Functional Properties of Rice Bran Proteins by High Pressure Treatment and Their Correlation with Surface Hydrophobicity

Changes in functional properties of rice bran proteins as influenced by high-pressure (HP) treatment (100–500 MPa, 10 min) were studied. Properties evaluated were protein solubility, water absorption capacity, oil absorption capacity, foaming capacity, foam stability, emulsifying activity, emulsion stability, least gelation concentration, and surface hydrophobicity. HP treatment at 100 and 200 MPa significantly improved the solubility and oil absorption capacity, while water absorption and foaming capacities increased further reaching the maximum at 500 MPa. Compared with the untreated control sample, the emulsifying activity and foam stability of treated samples were significantly higher and least gelation concentration was lower, but none of them showed any specific trend with pressure level. Emulsion stability and surface hydrophobicity increased with the pressure level until 400 MPa and decreased slightly at 500 MPa. Pearson correlation coefficients clearly showed that surface hydrophobicity was positively correlated with water absorption capacity, foaming capacity, emulsifying activity index, and emulsion stability index, but negatively correlated with least gelation concentration. The pressure treated rice bran protein possessed good functional properties for use as a food ingredient in the formulations.     

不同分子量海鲈鱼胶原蛋白肽组分的功能特性比较

本文采用不同截留分子量的超滤膜对海鲈鱼胶原蛋白肽溶液进行分级分离,采用碱性蛋白酶水解海鲈鱼加工副产物中提取的胶原蛋白制得的胶原蛋白肽溶液分成三个不同分子量组分SBCP1(Mw2000 u)、SBCP2(2000 uMw3000 u)和SBCP3(Mw3000 u),比较了海鲈鱼胶原蛋白肽它们的吸水性、持水性、溶解性、吸油性、乳化性和乳化稳定性、起泡性和起泡稳定性等功能特性。结果显示:小分子量的SBCP1组分的吸水性和溶解性最好;大分子量SBCP3组分的持水性、乳化性和乳化稳定性以及起泡性和泡沫稳定性最好;中等分子量的SBCP2组分的吸油性最好,这个结果提示了海鲈鱼胶原蛋白肽不同分子量组分的理化特性存在显著差异,其功能特性和分子量分布有密切关系。本研究为海鲈鱼胶原蛋白肽产品的开发利用提供了指导。     

桃仁清蛋白与大豆分离蛋白功能特性比较研究

为提高桃仁清蛋白(PKA)在食品工业中的应用,将其与大豆分离蛋白(SPI)对照,研究了PKA的溶解性、持水性、持油性、起泡性及泡沫稳定性、乳化性及乳化稳定性和凝胶性等功能特性.结果表明:与SPI相比,PKA具有很好的溶解性、泡沫稳定性、乳化稳定性及较低的凝胶质量浓度,持油性略高于SPI,但起泡性、乳化性及持水性较差;PKA溶解性受溶解条件影响较小.PKA具有良好的功能性质,适合作为食品添加剂或配料.     

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.     

Physicochemical and functional properties of a protein isolate produced from safflower (Carthamus tinctorius L.) meal by ultrafiltration

BACKGROUND: The protein isolate obtained from safflower meal by aqueous extraction and ultrafiltration was evaluated for its physicochemical and functional properties. RESULTS: Protein, ash and moisture contents of the safflower protein isolate were 901, 51 and 45 g kg^?1 respectively. Its water and oil absorption capacities were 2.22 mL H₂O g^?1 protein and 2.77 mL oil g^?1 protein respectively. Least gelation concentration was 20 g kg^?1 at pH 2, 6, 8 and 10 but 100 g kg^?1 at pH 4. Emulsifying properties were also affected by the pH: emulsifying activity and emulsion stability at pH 6 were 82.5 and 100% respectively. The highest foaming capacity (126%) occurred at pH 2; however, it increased by 104% with the addition of 0.25 g glucose g^?1 protein to the foam system. CONCLUSION: In the light of its functional properties found in this study, safflower protein isolate produced by ultrafiltration is recommended for use as an ingredient in food products such as salad dressing, meat products, mayonnaise, cakes, ice cream and desserts. Copyright © 2010 Society of Chemical Industry     

Isolation and characterization of protein isolated from defatted cashew nut shell: Influence of pH and NaCl on solubility and functional properties

This work reports the isolation of protein from defatted cashew nut shell (CNS), with the crude protein product containing 91.07% protein. Under its natural conditions, the solubility of this protein isolate is comparable (74.02%) to that of mustard green meal protein. The solubility of the protein isolate decreases with decreasing pH, with the minimum solubility observed at its isoelectric point (pH 3). The water holding capacity, oil holding capacity, foaming capacity, foam stability, emulsifying capacity and emulsion stability were found to be 2.56 cm³ H₂O/g protein, 4.28 cm³ oil/g protein, 76.88%, 70.98%, 62.0% and 79.0%, respectively. The profiles of these functional properties were determined with varying pH values and NaCl concentrations, and improved properties were observed in the alkaline pH range and in the presence of NaCl. Electrophoretic analysis showed that the high molecular weight protein globulin was the major protein in the protein isolate.     

Effect of Partial Proteolysis and Succinylation on Functionality of Corn Germ Protein Isolate

Corn germ protein isolate (CGPI) was partially hydrolyzed with trypsin and pepsin and succinylated at three levels. Various functional and electrophoretic properties of the native and modified protein were determined. Water absorption and foaming properties of CGPI were Improved by partial hydrolysis with trypsin; emulsifying capacity and nitrogen solubility were reduced; oil absorption was increased only slightly. CGPI pepsin hydrolyzate has decreased oil absorption, nitrogen solubility and emulsifying capacity but improved foaming properties; water absorption was unchanged. Treatment of CGPI with succinic anhydride improved water and oil absorption, nitrogen solubility and foaming capacity but decreased emulsifying capacity; foam stability was unchanged. Succinylation retarded electropohoretic mobility while hydrolysis altered band intensities.     

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。     

茶渣蛋白功能特性研究

基于茶业发展现状,本着开发利用茶渣蛋白为目标,对茶渣蛋白的功能特性开展研究。结果表明:茶渣蛋白在pH 4.0附近氮溶解指数最低,其吸水性为4.13g/g,吸油性为4.86g/g,茶蛋白具有优于大豆蛋白的乳化性、乳化稳定性、起泡性和起泡稳定性,且这四个功能特性几乎不受浓度影响,其原因可能是由于提取过程中部分变性所致。综合来说,茶渣蛋白的部分功能特性虽然优于大豆蛋白,但受溶解性限制,其应用仍需进一步开发。     

Characterisation and functional properties of proteins of some Indian chickpea (Cicer arietinum) cultivars

BACKGROUND: Chickpea (Cicer arietinum L.) proteins have received attention during recent years owing to their higher biological values and better functional ingredients than oilseed proteins. In this study the composition, fractionation, electrophoretic behaviour and functional properties of five chickpea protein concentrates were determined. RESULTS: The chickpea proteins contained 15.9–54.8 g kg^?1 albumin, 48.9–154.1 g kg^?1 globulin, 39.2–76.5 g kg^?1 glutelin and traces of prolamin. Electrophoresis of the various fractions revealed that albumin and globulin were made up of sub‐units of different molecular weights ranging from 7 to 96 kDa. Water and oil absorption of the protein concentrates varied from 1.15 to 2.75 g g^?1 and from 2.60 to 5.65 g g^?1 respectively. Foaming capacity and foam stability of the protein concentrates were good and improved with the addition of salt (10 g L^?1 NaCl) or sugar (100 g L^?1 sucrose) at both isoelectric and neutral pH. Emulsifying capacity and emulsion stability of the protein concentrates were good and excellent respectively. CONCLUSION: Protein concentrates prepared from chickpeas have potential use in food formulations owing to their good emulsifying/foaming and water/oil‐binding capacities. Copyright © 2008 Society of Chemical Industry     

新鲜和陈化莲子理化特性的初步比较

莲子在贮藏过程中,其蒸煮特性及食味值会发生明显变化,导致莲子陈化变质。为了解这一变化的内在原因,本实验以新鲜和陈化的广昌通芯白莲为实验材料,对两种莲子的吸水性和吸油性、乳化性和乳化稳定性、发泡性和泡沫稳定性、胶凝性进行对比研究。研究结果表明：新鲜和陈化莲子的水分、粗脂肪和蛋白质含量及醇提取物HPLC 图谱相似度差异都不显著,但各种功能特性存在较大差异,陈化莲子在吸水性和吸油性、乳化性、发泡性、胶凝性等方面都有所降低。贮藏导致莲子淀粉、蛋白质等成分的结构发生变化,从而使其功能特性发生了相应的改变。     

绿豆萌发过程中绿豆蛋白的功能特性及其抗氧化性

本文以绿豆为材料,研究了其萌发过程中绿豆蛋白的功能特性(溶解性、持水性、持油性、乳化性、起泡性、乳化稳定性、起泡稳定性)及抗氧化性(DPPH自由基清除率、金属离子螯合率、超氧阴离子自由基清除率)的动态变化。结果表明,随着萌发时间的不断延长,绿豆蛋白的溶解性、持水性、持油性、乳化性、起泡性均呈现先增加后降低的趋势,乳化稳定性和起泡稳定性得以增强。其中,溶解性萌发24 h时达到最高,萌发96 h最低;萌发的绿豆蛋白持水性、持油性和乳化性相对于未萌发的分别提高了1.57倍、4.13倍和2.47倍;乳化稳定性、起泡性和起泡稳定性较未萌发的分别提高了43.8%、46.6%和61.3%。此外,萌发过程中的绿豆蛋白抗氧化性呈现先升高后下降的趋势,萌发促进了绿豆蛋白的抗氧化性。其中,DPPH自由基清除率和金属离子螯合率均在绿豆萌发36 h达到最大,较未萌发的分别提高了73.8%和31.0%;超氧阴离子自由基清除率萌发48 h达到最大,较未萌发的提高了81.7%。随着绿豆萌发时间的延长,绿豆蛋白的功能特性和抗氧化性呈现先升高后下降的趋势,萌发中期(24~48 h)达到最大。因此,萌发提升了绿豆蛋白的功能特性和抗氧化性,扩大了其在食品加工中的应用,提高了其利用价值。     

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。     

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。     

Proteins isolated from Ganxet common bean (Phaseolus vulgaris L.) landrace: techno-functional and antioxidant properties

Ganxet protein isolates (GPI) were assessed for antioxidant and functional properties including emulsifying and foaming capacity. The protein content and water activity (a_w) value of GPI were 91.08 ± 4.15% and 0.248 ± 0.008%, respectively. The oil- and water-holding capacities of GPI were calculated as 2.76 ± 0.33 and 1.25 ± 0.11 g g⁻¹ of GPI, respectively (P < 0.05). Foaming and emulsifying properties were found to be pH-dependent (P < 0.05). The highest foaming capacity values were observed at pH 8.0 and 10.0 and were calculated as 86.25 ± 5.30% and 78.75 ± 1.77%, respectively. In addition, the generated emulsions were found to be stable, especially at pH 8.0 and 10.0 with emulsion stability values of 94.1 ± 0.0 and 93.9 ± 0.1, respectively (P < 0.05). Results obtained in the current study demonstrate the potential applications of Ganxet-derived proteins as techno-functional ingredients for the development of novel foods.     

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。     

Functional properties of 8S globulin fractions from 15 mung bean (Vigna radiata (L.) Wilczek) cultivars

The functional properties including solubility, water absorption capacity, oil absorption capacity, foaming properties and emulsifying properties of 8S globulin fractions from 15 mung bean cultivars were investigated in this study. In addition, the effects of pH on solubility, foaming properties and emulsifying properties were studied. The functional properties of the 8S globulin fractions varied significantly among the different mung bean varieties and exhibited better performance in solubility and emulsion stability compared with soya bean 7S protein. A negative correlation was found between water absorption capacity and oil absorption capacity. Remarkable differences in polypeptides constituents were observed in 8S globulin fractions, and the ratio of 11S/8S globulins has a positive effect on water absorption capacity while a negative effect on oil absorption capacity. As a function of pH, the emulsifying activity indexes of the 8S globulin fractions were found to be distinctly dependent on the solubility, while no significant correlation was found between the emulsifying stability and solubility, nor between the foaming properties and solubility. The foaming capacity showed a strong correlation with foam stability.     

不同制备方法桑叶蛋白功能性质的比较

以广东桑大10为原料,采用水提法制备叶蛋白浓缩液,用加热法、酸沉法、酸热法、盐析法沉淀叶蛋白,分别得到蛋白样品RC、SC、SR、LC。对所得样品进行功能性质测定,与大豆分离蛋白对比,得出不同样品的功能特点。结果表明,异亮氨酸、赖氨酸分别为桑叶粉的第一、第二限制性氨基酸。不同沉淀方法对叶蛋白的功能性质有显著影响:LC的溶解性、起泡性、乳化性、吸油性最好,均优于SC、SR及RC;SR的持水性优于SC及RC,但乳化性、起泡性较差;RC、LC的胶凝性最好。与SPI相比,4个样品的吸油性均优于SPI,持水性、胶凝性则显著低于SPI(p0.05);LC的乳化稳定性(68.57%)及SC的起泡性(40%)最好,显著优于SPI(54.86%、37.67%),RC与SPI相当,SR最差,显著低于SPI(p0.05)。LC电镜扫描结果显示其具有典型的蜂巢结构。     

牛骨蛋白的酶法改性工艺优化及其结构和功能特性研究

目的 以牛骨蛋白的乳化性为指标优化其酶法改性工艺,挖掘牛骨蛋白作为乳化剂稳定乳液的潜力,提高牛骨蛋白综合利用价值及在食品乳液中的应用。方法 采用碱性蛋白酶对牛骨蛋白进行改性,探究酶添加量、酶改性温度、体系pH和酶改性时间对牛骨蛋白乳化性的影响,并通过响应面试验优化酶法改性工艺,比较改性后牛骨蛋白的功能和结构变化。结果 牛骨蛋白的酶法改性最佳工艺为酶添加量2000U/g、改性温度为55℃、pH 7.2、改性时间1.9 h,此条件下牛骨蛋白的乳化活性、乳化稳定性、溶解度、持油性、持水性、起泡性和泡沫稳定性分别提高了53.85%、37.18%、51.43%、64.29%、50.16%、112.68%、167.22%;紫外吸收光谱、荧光光谱表明改性后牛骨蛋白的内部基团暴露程度增加,扫描电镜(SEM)观察牛骨蛋白微观结构发现改性后牛骨蛋白结构从有序的片状向不规则的纤维状转变。结论 牛骨蛋白在经过酶法改性后其乳化能力得到了明显提高,为牛骨蛋白在食品乳液体系的应用提供一定参考价值和理论支持。     

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.