黑龙江省小米主栽品种蛋白质功能性质分析

为了研究黑龙江省主栽小米蛋白质的功能性质,利用凯氏定氮、分光光度等方法对6种小米蛋白质的功能性质进行了分析。结果表明:朝新谷8号蛋白质的游离巯基及总巯基含量均最高,分别为40.23μmol/g和45.78μmol/g。吨谷1号蛋白质的疏水性最强,为533.25;6种小米蛋白质质量浓度为5 g/100 m L时,起泡力均最大,其中张杂谷蛋白质的起泡能力最强为20.4%。张杂谷蛋白质的乳化性及乳化稳定性最大,分别为53.49%和56.30%;当蛋白质的质量浓度增加时,6种小米蛋白的吸水和吸油能力均增加,红谷子蛋白质的吸水能力最强,为3.272%;吨谷1号蛋白质的吸油能力最强,为3.822%;6种小米蛋白质的最低凝胶点的蛋白质质量浓度在10 g/100 mL左右。此研究为黑龙江省小米品种的深加工提供了参考。     

黑龙江省主栽红小豆品种蛋白质功能性质分析

黑龙江省是红小豆的主要产区之一,为深入了解黑龙江省主栽红小豆蛋白质功能特性,本研究利用荧光及紫外分光光度法对农安红、状元红、农垦红二号、品鉴红、宝清红等五种红小豆蛋白质功能性质进行了测定分析。结果表明：五种红小豆蛋白质含量为19.32%-24.36%;在pH 4.0左右时,蛋白质溶解性最低;宝清红红小豆蛋白质游离巯基及总巯基含量均最高,分别为33.4±5.6 μmol/g和61.6±3.2 μmol/g;农垦红二号蛋白质疏水性最强,为425.5±0.5;五种红小豆蛋白质起泡性随质量浓度增大呈现先升高后降低的趋势,当质量浓度为6 g/100 mL时达到最大值;五种红小豆蛋白质起泡稳定性、乳化性、乳化稳定性、吸水性均随蛋白质浓度的增加而增大,吸油能力随着蛋白质所占比例的减小而增强;宝清红和农垦红二号凝胶点较低,在蛋白质浓度为11 g/100 mL就可以形成凝胶,当蛋白质质量浓度为13 g/100 mL时,五种红小豆蛋白质均产生凝胶现象。     

冰淇淋中蛋白质的主要功能及其理化性能

讨论了以水为溶剂和分散介质的整体连续相中鲜奶、奶粉的主要功能和重要性及其在冰淇淋中的应用，综合研究了蛋白质的水化性和水溶性，蛋白质溶液的粘度及蛋白质高分子的变性、胶凝、与风味物质的结舍、乳化性和起泡性。     

番木瓜籽蛋白质的提取工艺及其功能性质

以番木瓜籽为原料,经脱脂以酸沉碱溶法提取其中的蛋白质,并研究其乳化、起泡等功能性质。结果表明,最佳的提取工艺条件:料液比1∶40,p H为9.3,温度50℃,碱提时间120 min时最高提取率达到48.53%。番木瓜籽蛋白质的乳化性及稳定性随着蛋白质的浓度升高而升高,在p H3时最小,其乳化性在Na Cl浓度为0.2%时最大,而稳定性呈下降趋势;起泡性及稳定性随蛋白浓度升高而升高,在p H3.0,其起泡性和泡沫稳定性最小,在离子浓度(Na Cl)为0.2 mol/L时,其起泡性和泡沫稳定性最高。可见,此提取工艺效果较好,能将部分番木瓜籽蛋白质提取出来;番木瓜籽分离蛋白质乳化性和起泡性良好,这为番木瓜籽蛋白质的开发利用提供参考依据。      

豌豆蛋白质起泡、乳化功能特性研究

本试验研究了豌豆蛋白质的起泡性与乳化性。起泡性单因素试验发现,在3％蛋白质浓度、1．75mmol／LNaCl、50℃和pH值9．0时起泡性较高。运用统计学原理对起泡条件进行优化发现在3％豌豆蛋白、pH值10.0、1．00mmol／LNaCl和40℃时,起泡性最好（375％）。乳化性单因素研究发现,在3％蛋白质浓度、0．75mmol／LNaCl、45℃和pH值8．0条件下乳化性较好,正交试验表明,在2％蛋白质浓度、pH值8．0、0．75mmol／LNaa和45℃条件下乳化性最好。     

豌豆蛋白质起泡、乳化功能特性研究初探

为了更好的利用豌豆蛋白质和提高产品副加值,研究了豌豆蛋白质的起泡性与乳化性.在FAI单因素试验中发现,在3%蛋白质浓度、1.75 mmol/LNaCl、50℃和pH值9.0时FAI较高.在3%蛋白质浓度、0.75 mmol/LNaCl、45℃和pH值8.0时FAI较高.运用统计学原理对FAI条件进行优化,发现在3%豌豆蛋白、pH值10.0、1.00 mmol/L NaCl和40℃时,FAI最好(375%).EAI单因素研究发现,在3%蛋白质浓度、0.75 mmol/LNaCl、45℃和pH值8.0条件下EAI较好,正交试验表明,在2%蛋白质浓度、pH值8.0、0.75 mmol/LNaCl和45℃条件下EAI最好.     

豌豆蛋白质起泡、乳化功能特性研究初探

试验研究了豌豆蛋白质的起泡性伊AD与乳化性（EAI）。在FAI单因素试验中发现,在3％蛋白质浓度、1．75mmol／LNaCl、50℃和pH9．0时FAI较高。运用统计学原理对FAI条件进行优化,发现在3％豌豆蛋白、pH10．0、1．00mmol／LNaCl和40℃时,FAI最好（375％）。EAI单因素研究发现,在3％蛋白质浓度、0．75mmol/NaCl、45℃和pH8．0条件下EAI较好,正交试验表明,在2％蛋白质浓度、pH8．0、0．75mmol／LNaCl和45℃条件下EAI最好。     

非洲山毛豆蛋白质组成及其功能特性研究

以山毛豆种子为原料,研究其蛋白质组成及其功能特性。结果表明,脱脂山毛豆粉的总蛋白质量分数为47.11%,其中清蛋白、球蛋白、醇溶蛋白和谷蛋白的质量分数分别为64.04%、8.83%、11.06%和14.50%,另有1.57%的难溶复合蛋白。清蛋白和谷蛋白在pH4和球蛋白和醇溶蛋白在pH5溶解性、起泡性、乳化性均差,而泡沫稳定性和乳化稳定性较好。各蛋白组分的持水持油性均较好。在pH5或pH4的条件下,清蛋白和球蛋白的溶解性、起泡性和乳化性较好,其余蛋白组分相对较差。与大豆蛋白相比,山毛豆主要蛋白清蛋白有较好的溶解度、持水持油性、起泡性、泡沫稳定性、乳化性及乳化稳定性。     

茶渣碱提取物中的蛋白质性质分析

茶渣的蛋白质含量较高,可通过碱提法高效获得,然而该法获得的茶渣蛋白质可能与多酚、糖类物质等发生反应,影响其在食品工业中的应用。本研究测定绿茶渣蛋白质提取物的理化性质与生理活性,对碱提法获得的茶渣蛋白质进行分析。采用酶法改进茶渣蛋白质的乳化性、起泡性、抗氧化性。结果表明,提取物中蛋白质含量为52%,其等电点(pI)为3.6,可主要分为3个组分。茶渣蛋白质的溶解度、分散性、起泡性和乳化性与溶液pH值呈正相关性。当茶渣蛋白质质量浓度为80 mg/mL时,对嗜冷菌和假单胞菌的抑菌率分别为98%和93%。经胃蛋白酶处理后,茶渣蛋白质的起泡性为58.3 mL/g,约是未处理样品的2倍。乳化性为100.0 mL/g,约是未处理样品的4倍,抗氧化性变化较小。经碳水化合物复合酶Viscozyme~?L处理后,茶渣蛋白质的起泡性提至52.4 mL/g,乳化性降至12.0 mL/g,抗氧化性提升约0.5倍。试验证明茶渣蛋白质提取物及其酶解产物具有较好的功能性质和开发新型功能性食品的应用潜力。     

大豆蛋白质的构造和功能特性(中)

介绍了大豆蛋白质的组成、氨基酸成分、分子结构、溶解性，着重分析了大豆蛋白的食品功能特性中的乳化性、起泡性、水化性、凝胶性的相互关系以及这些特性与组成结构的关系，对大豆蛋白产品的生产提供了一定的理论依据和参考。     

大米水解蛋白的物化性质研究

研究了大米水解蛋白(HRP)在不同浓度、pH值和糖类物质存在时的乳化、发泡等应用性能。结果表明:随着pH值的增加,其溶解度、发泡能力和乳化活性等均有明显增加,但其泡沫稳定性和乳化稳定性却未呈现规律性变化。提高HRP的浓度或在HRP溶液中添加可溶性淀粉可显著改善HRP的乳化活性,但可溶性淀粉的添加量高于HRP时,其乳化稳定性呈下降趋势。葡萄糖和蔗糖对HRP溶液乳化性能也有一定影响。     

Surface functional properties of blood plasma protein fractions

The solubility, foaming and emulsifying properties of porcine blood plasma and its main protein fractions (serum, globulins and albumin) were investigated at pH 4.5, 6.0 and 7.5 in order to clarify the contribution of each fraction and encourage the optimisation of plasma-derived products. Soluble protein contents above 85% were obtained in all samples. Plasma, serum and albumin showed good foaming capacities, reasonably similar at different pH conditions, although the highest foam stability corresponded to both albumin and plasma at pH 4.5 and 6.0. All protein fractions showed good emulsifying activities, but the stability of the formed emulsions decreased with acidification, being emulsions of albumin and globulins at pH 7.5 the most stable ones. In addition, the interaction indexes calculated to investigate protein–protein interactions revealed synergistic interactions between albumin and globulins when in co-occurrence in their foaming capacity at pH 6.0 and 7.5, and in the stability of emulsions at pH 4.5 and 6.0, but slightly negative effects in the solubility of the mixture, and a great decrease in the stability of emulsions at pH 7.5. On the other hand, the elimination of fibrinogen improved the stability of emulsions and foams at acidic conditions.     

Functional properties of fish protein hydrolysates from Pacific whiting(Merluccius productus) muscle produced by a commercial protease

Pacific whiting (Merluccius productus) muscle was used to produce hydrolysates with 10%, 15% and 20% degree of hydrolysis (DH) using the commercial protease Alcalase^® and were characterized at pH 4.0, 7.0 and 10 according their solubility, emulsifying and foaming properties. Protein recovered in soluble fractions increased proportionally with the hydrolytic process, yielded 48.6 ± 1.9, 58.6 ± 4.1 and 67.8 ± 1.4 of total protein after 10%, 15% and 20% DH, respectively. Freeze-dried hydrolysates presented almost 100% solubility (p > 0.05) at the different pHs evaluated. Emulsifying properties (EC, EAI and ESI) were not affected by DH as most samples showed similar (p > 0.05) results. Higher EC (p ? 0.05) than sodium caseinate, used as control, were obtained at pH 4 for most hydrolysates. Hydrolysates showed very low foaming capacity not affected by pH; but foam stability was equal or even better (p > 0.05) than bovine serum albumin (BSA), except at pH 4.0. Results suggest that hydrolysates from Pacific whiting muscle can be produced with similar or better functional properties than the food ingredients used as standards.     

Heat-induced modifications in the functional and structural properties of vicilin-rich protein isolate from kidney (Phaseolus vulgaris L.) bean

Heat-induced changes in the physico-chemical (and/or functional) and structural properties of protein isolate from kidney beans (KPI) were characterised. The extent of protein denaturation, free sulphydryl contents, surface hydrophobicity, as well as structural characteristics of the proteins were evaluated. Analyses of size-exclusion chromatography combined with laser scattering showed that the heating at 95 °C led to transformation of 7S-form vicilin to its 11S-form, and even higher molar mass (MW) oligomers or polymers. Moderate heating (for 15–30 min) significantly improved protein solubility, emulsifying and foaming activities (at neutral pH), whilst extensive heating (for 60–120 min) on the contrary decreased these properties. Spectral analyses of fluorescence and/or Raman spectroscopy showed that tertiary and secondary conformations of protein in KPI were remarkably affected to a varying extent by the heating. The results suggested a close relationship between functional properties of the vicilin from kidney bean and its conformational characteristics.     

Improvement of functional properties of whey soy protein phosphorylated by dry-heating in the presence of pyrophosphate

The physicochemical and functional properties of a whey soyprotein (WSP), which was phosphorylated by dry heating, were investigated. The phosphorus content of WSP was 0.85 g/100 g by dry-heating at pH 4.0 for 5 days in the presence of pyrophosphate. ³¹P NMR spectral data suggested that the serine and sugar of WSP were phosphorylated. Although changes in the random coil structure of WSP measured by circular dichroism were mild, increased surface hydrophobicity and decreased tryptophan fluorescence intensity were observed following phosphorylation. Phosphorylation improved the stability against heat-induced insolubility, emulsifying properties, foaming properties, water absorption capacity, and oil absorption capacity of WSP. These results suggested that dry-heating phosphorylation is a useful method for improving the functional properties of WSP.     

Emulsifying properties of sweet potato protein: Effect of protein concentration and oil volume fraction

The effect of protein concentrations (0.1, 0.25, 0.5, 1.0, 1.5 and 2.0% w/v) and oil volume fractions (5, 15, 25, 35 and 45% v/v) on properties of stabilized emulsions of sweet potato proteins (SPPs) were investigated by use of the emulsifying activity index (EAI), emulsifying stability index (ESI), droplet size, rheological properties, interfacial properties and optical microscopy measurements at neutral pH. The protein concentration or oil volume fraction significantly affected droplet size, interfacial protein concentration, emulsion apparent viscosity, EAI and ESI. Increasing of protein concentration greatly decreased droplet size, EAI and apparent viscosity of SPP emulsions; however, there was a pronounced increase in ESI and interfacial protein concentration (P < 0.05). In contrast, increasing of oil volume fraction greatly increased droplet size, EAI and emulsion apparent viscosity of SPP emulsions, but decreased ESI and interfacial protein concentration significantly (P < 0.05). The rheological curve suggested that SPP emulsions were shear-thinning non-Newtonian fluids. Optical microscopy clearly demonstrated that droplet aggregates were formed at a lower protein concentration of <0.5% (w/v) due to low interfacial protein concentration, while at higher oil volume fractions of >25% (v/v) there was obvious coalescence. In addition, the main components of adsorbed SPP at the oil–water interface were Sporamin A, Sporamin B and some high-molecular-weight aggregates formed by disulfide linkage.     

Enzymatic hydrolysis and their effects on conformational and functional properties of peanut protein isolate

The effects of limited enzymatic hydrolysis by Alcalase on the conformational and functional properties of peanut (Arachis hypogaea L.) protein isolate (PPI) were investigated. Acid subunits of arachin were most susceptible to Alcalase hydrolysis, followed by conarachin and the basic subunits of arachin. Enzymatic hydrolysis increased the thermal stability of arachin and led to a sharp increase in the number of disulphide bonds with a decrease of the sulphydryl group in PPI hydrolysates in comparison with PPI. The analysis of intrinsic fluorescence spectra indicated a more moveable tertiary conformation of PPI hydrolysates than PPI. The limited emzymatic hydrolysis improved the functional properties of PPI, such as protein solubility and gel-forming ability, but impaired the emulsifying activity index.     

蛋白组分对米蛋白功能性质影响的研究

以不同配比米蛋白组分的样品为试材,比较各样品的功能性质变化,明确各蛋白组分对蛋白产品品质影响的差异,为今后进行分子设计和重组生产米蛋白产品提供理论支撑。通过各蛋白样品的溶解性,乳化特性,起泡特性,持水性/持油性等功能性质研究,结果表明,米糠浓缩蛋白的溶解性比大米浓缩蛋白高200%左右;米糠蛋白各功能性质显著优于大米蛋白,但大米蛋白的起泡稳定性比米糠蛋白提高近20%。米蛋白中的清蛋白提高产品的溶解性、持水性/持油性,降低起泡稳定性;醇溶蛋白提高产品的乳化特性;谷蛋白提高产品的起泡稳定性。蛋白产品的功能性质与蛋白组分的组成密切相关。