Peanut protein concentrate: Production and functional properties as affected by processing

Peanut protein concentrate (PPC) was isolated from fermented and unfermented defatted peanut flour by isoelectric precipitation and physical separation procedures. PPC was dried by spray or vacuum drying. PPC powders from each drying technique were evaluated for proximate composition and functional properties (protein solubility, water/oil binding capacity, emulsifying capacity, foaming capacity and viscosity) along with defatted peanut flour and soy protein isolate as references. PPC contained over 85% protein versus 50% protein in the defatted peanut flour used as raw material for PPC production. PPC had a solubility profile similar to that of peanut flour, with minimum solubility observed at pH 3.5–4.5 and maximum solubility at pH 10 and higher. Roasting of peanut reduced all functional properties of defatted peanut flour while fermentation had the reverse effect. The type of drying significantly affected the functional properties of PPC. Spray dried PPCs exhibited better functional properties, particularly emulsifying capacity and foaming capacity, than vacuum oven dried PPC. Spray dried PPCs also showed comparable oil binding and foaming capacity to commercially available soy protein isolate (SPC). At equivalent concentrations and room temperature, PPC suspension exhibited lower viscosity than soy protein isolate (SPI) suspensions. However, upon heating to 90 °C for 30 min, the viscosity of PPC suspension increased sharply. Results obtained from this study suggest that the PPC could be used in food formulations requiring high emulsifying capacity, but would not be suitable for applications requiring high water retention and foaming capacity. PPC could be a good source of protein fortification for a variety of food products for protein deficient consumers in developing countries as well as a functional ingredient for the peanut industry. The production of PPC could also add value to defatted peanut flour, a low value by-product of peanut oil production.     

不同干燥方法对花生蛋白功能特性的影响

以花生蛋白为原料,分别采用热风干燥、真空干燥、微波干燥和微波结合真空干燥对花生蛋白进行干燥处理,比较不同的干燥方式对花生蛋白功能特性(吸油性、持水性、乳化性、乳化稳定性、起泡性能和起泡稳定性)的影响。实验表明,微波结合真空干燥的花生蛋白不仅干燥时间短,而且具有较好的功能特性,微波结合真空干燥是一种干燥花生蛋白的适宜方法。     

Influence of Oven-Drying Temperature on Physicochemical and Functional Properties of Date Fibre Concentrates

Agri-food by-products rich in dietary fibres may be used as feeds and health foods. Owing to its high fibre content, date flesh could be useful in human nutrition. It is interesting to study the influence of oven-drying temperatures of date fibre concentrates (DFC) on their physicochemical and functional properties for possible use as a potential fibre source in the enrichment of food. DFC from 11 Tunisian date cultivars were dried at different temperatures (40, 50 and 60 °C) and analysed regarding proximate composition (moisture, ash, protein and lipids), physicochemical (water activity (a _w), pH) and functional properties (water holding capacity (WHC), swelling capacity (SC), oil holding capacity (OHC) and emulsifying capacity (EC)). DFC dried at different temperatures showed interesting functional characteristics such as hydration properties, high OHC (2.73–4.60 g oil/g dry fibre) and EC (5.93–12.87%) values. Although drying temperatures promoted little modifications affecting the physicochemical properties of DFC, significant decreases in WHC, SC and EC of DFC were noticed at the highest temperature (60 °C) for most of the date varieties. The observed influence of drying temperature on functional DFC properties calls for the use of low temperature in order to obtain DFC as suitable food ingredient.     

干燥方式对秋葵超微粉理化特性及抗氧化活性的影响

以热风、真空冷冻两种干燥方式对4 个品种（爱木1号（爱1）、老蓝、孟1、爱木5号（爱5））的秋葵果 实进行干燥并将其超微粉碎,研究干燥方式对秋葵超微粉的理化特性及其抗氧化活性的影响。结果表明：热风干 燥与真空冷冻干燥的秋葵超微粉在物理特性（溶解性、持水力、容重）、VC含量、叶绿素含量和抗氧化活性方面 都存在显著差异（P＜0.05）。与热风干燥相比,真空冷冻干燥的秋葵超微粉溶解性大,持水力、容重小,VC含量 高,且其甲醇提取液对1,1-二苯基-2-三硝基苯肼和O2 － ·的清除能力较强。真空冷冻干燥后,4 个品种的秋葵超微粉 除持水力和容重外,其他指标存在显著差异（P＜0.05）;其中,孟1超微粉的溶解度最高,VC含量丰富,抗氧化 活性最强。本研究结果认为真空冷冻干燥的秋葵超微粉在物理特性方面优于热风干燥的,且具有较高的VC含量和 抗氧化活性,说明该干燥方式更适用于秋葵超微粉的生产,尤其是采用真空冷冻干燥方式加工孟1品种的秋葵更具 有市场价值。     

Composition and functional properties of hemp seed protein isolates from various hemp cultivars

Hemp seed protein isolates (HPI) were extracted from seven commercial hemp cultivars, a Cornell breeding line, and a commercial hemp heart product, and their composition and functional properties were investigated. HPI contained different ratios of edestin, vicilin, and albumin proteins, which affected protein solubility and functionality. Higher protein solubility was associated with cultivars that contained more vicilin and albumin, which influenced the subsequent functional properties of HPI. Significant differences in water holding capacity (0.83–1.05 g water/g protein isolate), oil holding capacity (1.28–1.81 g oil/g protein isolate), foam capacity (52.9%–84.9%), and foam stability (68.1%–89.4%) were observed across HPI. The Cornell hemp breeding line exhibited the highest protein solubility at pH 7.0 and was uniquely capable of forming an emulsion. The relationship identified between hemp seed protein composition and functionality, in conjunction with the demonstration of an on-going hemp breeding line, suggest that continued, targeted development of hemp cultivars can improve its seed protein functional properties for ingredient utilization in plant-based foods.     

Physicochemical and functional properties of lentil protein isolates prepared by different drying methods

Lentil protein isolate (LPI) extract was converted into powder by freeze drying, spray drying and vacuum drying. Differences in particle size distribution, protein subunit composition and colour and surface morphology were observed amongst the three drying methods. Spray and freeze-dried LPI powders exhibited higher solubility (81% and 78%, respectively) compared to vacuum dried powders (50%). The spray dried powders showed a low water absorption capacity (0.43 ± 0.02 g/g) compared to freeze (0.48 ± 0.02 g/g) and vacuum-dried (0.47 ± 0.01 g/g) LPI powders. Spray and freeze-dried powders displayed better gelation ability and higher gel strength, compared to vacuum-dried powder. Both spray and freeze-dried gels showed typical viscoelastic gel characteristics, with G′ dominating over G″ and very low loss tangent. The holding time required for gelation of vacuum dried powder at 90 °C was significantly longer, compared to spray and freeze dried powders. Hence, drying methods used for preparation of lentil protein isolate powders can affect physicochemical and associated functional properties.     

Physicochemical characteristics and functional properties of grape (Vitis vinifera L.) seeds protein

The amino acid composition, physicochemical and functional properties of grape (Vitis vinifera L.) seeds protein (GSP) were evaluated and compared with those of soybean protein isolate (SPI). Amino acid analyses of GSP revealed high levels of glutamic/glutamine, glycine and aspartic/asparagines. SDS‐PAGE analysis demonstrated that globulin was the major protein component in GSP, whose subunit molecular weights were mainly varied from 25.5 to 40.0 kDa. The isoelectric pH of GSP was found to be at the acidic pH of around 3.8. At all the pHs tested except pH 2.0, no significant changes of GSP secondary structure were observed. GSP exhibited beneficial functional properties such as preferable solubility and emulsifying activity, while the foaming properties and water holding capacity were relatively poor compared to SPI. It could then be employed to soup, sauce, beverage or meat product for improving nutritional and sensory quality of these foods at appropriate pHs.     

杏鲍菇分离蛋白和清蛋白的理化性质及功能分析

以杏鲍菇为原料,分别利用碱溶酸沉法提取杏鲍菇分离蛋白（Pleurotus eryngii protein isolate,PEPI）、Osborne法分离主要蛋白组分,并研究其理化性质和功能分析。结果表明,杏鲍菇的蛋白质量分数为17.57%（以干质量计）,以杏鲍菇清蛋白（Pleurotus eryngii albumin,PEA）为主,占总分离蛋白组分的81.12%。PEPI和PEA中均含18?种氨基酸,且必需氨基酸含量分别占总氨基酸含量的40.80%和40.51%。与PEPI相比,PEA的表面疏水性（265.25）显著高于PEPI（164.27）（P＜0.05）,而总巯基、二硫键含量较低,分别为61.53?μmol/g和10.39?μmol/g;热变性温度（100.98?℃）低于PEPI（108.27?℃）,且PEA持水性（1.64?mL/g）、持油性（5.59?mL/g）显著低于PEPI（3.58、8.36?mL/g）（P＜0.05）。PEPI和PEA的溶解性、起泡性、泡沫稳定性、乳化性及乳化稳定性随pH值的变化趋势均相似,在等电点时均为最低。傅里叶变换红外光谱显示PEPI和PEA的二级结构主要是β-折叠和β-转角,扫描电镜观察PEPI呈蜂巢结构。相比PEA,PEPI具有更好的理化性质和功能特性。     

不同干燥方式对金针菇菇根粉物理性质的影响

采用热风干燥、微波真空干燥、变温压差膨化干燥及真空冷冻干燥技术制备金针菇菇根粉,研究不同干燥方式对金针菇菇根粉物理性质的影响。结果表明:真空冷冻干燥粉体色泽保持最好,其次是微波真空干燥和变温压差膨化干燥;真空冷冻干燥和微波真空干燥粉体粒度和跨度较小,且粒度更均匀。热风干燥和变温压差膨化干燥粉体流动性及压片成型性较好;微波真空干燥和真空冷冻干燥粉体持水能力较强,真空冷冻干燥粉体持油力最强,达1.8 g/g;热风干燥和变温压差膨化干燥粉体水溶性较强,微波真空干燥最弱。真空冷冻干燥和微波真空干燥金针菇菇根粉适宜作为功能原料添加到食品中或吸附在食品表面。热风干燥和变温压差膨化干燥菇根粉适宜压制片剂及进行可溶性成分提取。      

Preparation of spent brewer's yeast β-glucans for potential applications in the food industry

A preparation of β‐glucan, obtained from spent brewer's yeast, was evaluated for potential food applications. This material was autolysed and the cell walls that were obtained were homogenized, extracted firstly with alkali, then with acid, and then spray dried. Effects of the homogenization on the chemical composition, rheological properties and functional properties of β‐glucan were investigated. Homogenized cell walls exhibited higher β‐glucan content and apparent viscosity than those which had not been homogenized because of fragmentation of the cell walls. When compared with commercial β‐glucan from baker's yeast, it was found that the β‐glucan obtained from this study had higher apparent viscosity, water‐holding capacity and emulsion stabilizing capacity, but very similar oil‐binding capacity. These findings suggest that β‐glucan obtained from brewer's yeast can be used in food products as a thickening, water‐holding, or oil‐binding agent and emulsifying stabilizer.     

紫苏分离蛋白功能性研究

为了开发紫苏蛋白在食品工业中的应用,以大豆分离蛋白为对照,研究紫苏分离蛋白的功能特性。结果表明：紫苏分离蛋白的溶解性与大豆分离蛋白的溶解性随pH值变化的趋势基本一致,但在等电点时紫苏分离蛋白的溶解性高于大豆分离蛋白。在pH7.0时,紫苏分离蛋白的持水性、起泡性及泡沫稳定性、乳化性和凝胶性均不及大豆分离蛋白。但紫苏分离蛋白的吸油性仅稍小于大豆分离蛋白,此外,在紫苏分离蛋白的蛋白质质量浓度为3g/100mL以后,其乳化稳定性与大豆分离蛋白的乳化稳定性基本相当。紫苏分离蛋白在食品加工中作为一种蛋白质强化剂具有一定潜力。     

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.     

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.     

喷雾干燥和冷冻干燥莲子蛋白结构及其功能特性的比较

采用碱溶酸沉的方法提取莲子湿蛋白,通过喷雾干燥和冷冻干燥两种方法制备莲子蛋白粉,并对两种蛋 白粉的结构及其功能特性进行比较分析。研究表明：与冷冻干燥莲子蛋白（freeze-dried lotus seed protein,FLSP） 相比较,喷雾干燥莲子蛋白（spray-dried lotus seed protein,SLSP）明度大,色泽较好;扫描电子显微镜结果显示 SLSP呈现不规则的向内折叠起皱的球状结构,FLSP为盘状的大片层结构;X射线衍射测定表明两种干燥方法所得 蛋白都呈现非结晶性;圆二色谱进一步表明两种干燥蛋白的二级结构无明显变化,但两者均从有规则的结构向无规 则的结构转化;SLSP除了持水性和起泡性优于FLSP（P＜0.05）,其他功能特性如溶解性、持油性、乳化特性均有 所降低。因此,不同的干燥方法会改变莲子蛋白的结构特性,并进一步影响其功能特性,预示不同干燥方法所获得 的蛋白粉可能适用于不同产品的加工。     

Physicochemical and functional properties of flour and protein isolates extracted from seinat (Cucumis melo var. tibish) seeds

The physicochemical and functional properties of seinat seed flour (SSF), defatted seinat flour (DSSF), and protein isolates were studied. Protein was extracted from DSSF using an alkali solution with isoelectric precipitation and freeze drying. Freeze dried seinat seed protein isolates (FSSPI), SSF, and DSSF were evaluated for their physicochemical and functional properties. SSF contained high levels of crude fat and fiber (31.13% and 24.75%, respectively). FSSPI contained 91.83% protein versus 28.58% for SSF. The amounts of potassium, the mineral with the highest content, were 9,548.33, 6,439.03, and 1,029 mg/100 g in SSF, DSSF, and FSSPI, respectively. The functional properties were variable among samples. The protein solubility of FSSPI was significantly higher (p<0.05) than for DSSF and SSF. FSSPI has a significantly better (p<0.05) foaming capacity, water/fat absorption capacity, and bulk density than SSF and DSSF. FSSPI also showed an emulsifying capacity comparable to commercial soy protein isolates.     

Physicochemical and functional properties of goat milk whey protein and casein obtained during different lactation stages

During lactation, goat milk contains colostrum, transitional milk, mature milk, and end milk. The protein present in goat milk during different lactation periods has different characteristics. This study aimed to characterize the protein profile of goat milk samples obtained at different lactation stages and to identify changes in the physicochemical and functional properties of whey protein and casein from goat milk collected at 1, 3, 15, 100, and 200 d after calving. The results demonstrated that the lactation period had a great influence on the physicochemical and functional properties of goat milk whey protein and casein, especially the protein properties of colostrum on the first day after delivery. The denaturation temperature, hydrophobicity, and turbidity of whey protein were significantly higher on the first day postpartum than at other lactation periods. Correspondingly, the colostrum whey protein also had better functional properties, such as emulsification, oil holding capacity, and foaming properties on the first day postpartum than at other lactation periods. For casein, the turbidity, particle size, water holding capacity, and foaming properties on the first day after delivery were significantly higher than those at other lactation periods, whereas the denaturation temperature, oil holding capacity, and emulsification followed the opposite trend. For both whey protein and casein, the 2 indicators of emulsifying properties, namely, emulsifying activity index and the emulsion stability, also followed an opposite trend relative to lactation stage, whereas the changes in foaming capacity with the lactation period were completely consistent with the change of foaming stability. These findings could provide useful information for the use of goat milk whey protein and casein obtained during different lactation stages in the dairy industry.     

不同干燥方式桑叶粉物理特性、氨基酸及挥发性成分分析

对比分析热泵干燥、微波干燥、真空冷冻干燥三种干燥方式对桑叶粉色泽、粉体特性、氨基酸组分及挥发性成分的影响;结果表明真空冷冻干燥L*、b*最大,a*最小;微波干燥润湿性、持水力和持油力最差,溶解性和堆积密度最强;真空冷冻干燥桑叶粉润湿性、吸湿性、持水力和持油力最强,堆积密度最小;微波干燥桑叶粉总氨基酸、必需氨基酸以及必需...     

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.     

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。     

厚壳贻贝分离蛋白提取、氨基酸组成及理化特性研究

以厚壳贻贝脂溶性物质提取后的副产品-贻贝粉为原料,采用等电点沉淀法,结合乙醇/水脱酚及透析分离提取厚壳贻贝蛋白并对其氨基酸组成及理化特性进行研究。最终得到分离蛋白的蛋白含量为93.8%,氨基酸组成在提取前后无显著性变化,必需氨基酸含量丰富,约为总氨基酸的36%,其中赖氨酸、亮氨酸、苯丙氨酸、苏氨酸和缬氨酸含量较高,均可达到FAO/WHO推荐值。厚壳贻贝分离蛋白具有较好的溶解性,其持水性、吸油性以及起泡性均优于大豆分离蛋白和鸡蛋蛋白,但乳化性不及大豆分离蛋白和鸡蛋蛋白。研究结果表明,厚壳贻贝蛋白可作为一种良好的蛋白质资源,通过优化提取方法及对其理化特性研究的深入,可极大提高厚壳贻贝脂溶性物质提取后的副产品-贻贝粉的综合利用。