Foaming properties of oilseed proteins

Oilseeds are important sources of edible proteins. Their varieties varied in oil and protein content; sesame and rapeseeds had the highest oil content, but soybean and glandless cottonseeds had the highest protein content. Foaming properties of oilseed proteins are important for the domestic market to be used in the preparation of various food products. Whole rapeseed had the highest foam capacity followed by soybean, sunflower, safflower, glandless cottonseed, peanut and finally sesame. The extraction of lipids from oilseeds caused a significant improvement in their foam capacity and foam stability. High positive correlation was found between soluble proteins and foam capacity of oilseeds. The foam capacity was high at pH 7, and decreased below it reaching a minimum at pH 4. The foam stability also varied with pH; being maximum at the isoelectric point and minimum at pH 7. The foam capacity of oilseed protein isolates decreased with the prolongation of heating time at 100 °C.     

棉籽蛋白功能特性的研究

考察了棉籽浓缩蛋白、沉淀蛋白和溶解蛋白3种棉籽蛋白的氮溶指数、吸水性、吸油性、起泡性与泡沫稳定性、乳化性与乳化稳定性等功能特性。结果表明,棉籽溶解蛋白的乳化性和起泡性较佳;棉籽浓缩蛋白和沉淀蛋白,除吸油、吸水能力强之外,其他的功能特性均较差。在吸水性方面,棉籽蛋白的吸水性要低于菜籽沉淀蛋白,但高于大豆沉淀蛋白。在吸油性方面,棉籽蛋白均低于菜籽蛋白和大豆蛋白。     

Physicochemical and functional properties of albumin,globulin and glutelin fractions of green lentil seed

Defatted lentil seed flour proteins were separated into their constituent albumin (ALB), globulin (GLB) and glutelin (GLT) fractions followed by determination of their structural and functional properties. The GLB fraction demonstrated superior solubility (84%–100%) at acidic and alkaline pH values when compared to the lower values for ALB and GLT. Amino acid composition analysis showed lower contents of hydrophobic and sulphur-containing residues for GLB. However, GLB had the highest in vitro protein digestibility, which may be due to lower contents of rigid secondary structure fractions like the β-sheet and β-turns. In contrast, water and oil holding capacities as well as gelling ability were better for GLT and ALB than GLB. The GLT fraction formed very poor emulsions at pH 3 and 5 but emulsification was significantly (p < 0.05) improved (smaller oil droplets) at pH 7 and 9. Foaming capacity was strongest for GLB, especially at pH 5, 7 and 9 where increase in protein concentration had a negative effect on foam formation. Overall, the protein type and pH of the environment had stronger effects on emulsion and foaming properties than the protein concentration.     

物理改性对棉籽分离蛋白功能特性影响

采用水浴加热、超声波和微波辐射三种方法对棉籽分离蛋白进行改性处理,研究不同方法对蛋白的溶解性、持水性、吸油性、乳化性、乳化稳定性和起泡性等影响。实验结果表明,不同处理方法对棉籽分离蛋白功能特性均有一定改善,其中加热方法对蛋白起泡性影响较大,提高53.2%;微波辐射方法对蛋白溶解性、持水性、吸油性、乳化性有明显改善,分别提高5.0%、70.3%、6.5%、35.8%;超声波方法对蛋白乳化稳定性及起泡稳定性有一定改善,乳化稳定性提高51.6%;三种方法以微波辐射改性方法效果最优。     

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.     

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。     

The physicochemical parameters during dry heating strongly influence the gelling properties of whey proteins

In this study we determined the composition (proportion of native proteins, soluble and insoluble aggregates) and quantified the gelling properties (gel strength and water holding capacity) of pre-texturized whey proteins by dry heating under controlled physicochemical conditions. For this purpose, a commercial whey protein isolate was dry heated at 80 °C (up to 6 days), 100 °C (up to 24 h) and 120 °C (up to 3 h) under controlled pH (2.5, 4.5 or 6.5) and water activity (0.23, 0.32, or 0.52). Gelling properties were quantified on heat-set gels prepared from reconstituted pre-texturized proteins at 10% and pH 7.0. The formation of dry-heat soluble aggregates enhanced the gelling properties of whey proteins. The maximal gelling properties was achieved earlier by increasing pH and water activity of powders subjected to dry heating. An optimized combination of the dry heating parameters will help to achieve better gelling properties for dry heated whey proteins.     

Functional properties of meal products of the nigerian ‘red skin’ groundnut (arachis hypogaea L.)

Three products were prepared from the Nigerian red skin groundnuts; undefatted flour (UGF), hexane-extracted defatted flour (DGF), and a protein concentrate made by isoelectric centrifuging (GPC). Their functional properties were examined and compared with those of egg white powder and yolk to characterise their potential use in food preparations. The GPC performed better in functional properties than DGF and UGF. Emulsification capacity was higher than that of UGF and DGF but comparable to that of egg yolk. A 5% dispersion whipped better than egg white powder and produced more stable foams over a 3-h period. Both water and fat absorption capacities were better and a 10% aqueous dispersion of the GPC was more viscous than similar dispersions of DGF and UGF respectively. Least gelation concentrations were 5, 3 and 4% for GPC, DGF and UGF. The high emulsification capacity, water and fat absorption capacities suggest that the GPC could be used in processed meat products, confections and beverages while the good whipping properties point to its potential use in products like meringue, bread and hot cakes.     

米糠蛋白酶解产物功能特性及乳液稳定性研究

目的 研究改善米糠蛋白的溶解性。方法 选用胰蛋白酶对米糠蛋白进行酶法改性,分析其在不同水解度下(1%、3%、7%)酶解产物的功能特性及不同pH、离子强度和温度对米糠蛋白酶解产物乳液的影响。结果 酶解可显著提高米糠蛋白的溶解性,在水解度7%时的溶解性最高;而酶解产物的起泡性、起泡稳定性、乳化性和乳化稳定性呈现先增加后下降的趋势,并在水解度为3%时达到最大值;经酶解后持油性显著增加,而持水性显著降低。米糠蛋白及酶解产物乳液在不同pH下平均粒径和电位呈现相似变化趋势,在等电点附近极不稳定,在pH7-8时乳液趋于稳定;低水解度(1%、3%)的酶解产物乳液对高温和盐离子的抵抗能力高于米糠蛋白。结论 水解度为3%的酶解产物,其功能特性显著提升,制备的乳液在高离子强度和加热条件下较为稳定,该结果为米糠蛋白酶解产物制备食品乳液提供理论依据。     

棉籽分离蛋白功能性质的研究

考察了棉籽各分离蛋白,包括清蛋白、球蛋白、醇溶谷蛋白及谷蛋白在棉籽蛋白中所占的比例,研究了各蛋白的功能性质,包括吸水性、吸油性、乳化性和乳化稳定性、起泡性与泡沫稳定性以及各蛋白的抗氧化活性。结果表明,谷蛋白为棉籽蛋白中的主要分离蛋白,棉籽清蛋白具有较高的吸水性、乳化性、乳化稳定性以及起泡性,吸油性相对较差,适用性相对较好,但在棉籽蛋白中含量较少,而谷蛋白的吸水性、乳化性、起泡性很差,具有一定的吸油性,适用性较差,但在棉籽蛋白中含量丰富,在抗氧化活性方面,各分离蛋白的抗氧化活性能力都较差,需要进行改性处理。     

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。     

Nutritional Evaluation of the Protein in Oilseed Products Heated with Sugars

Defatted flours and protein isolates from glandless cottonseed, peanut, and soybean were complexed with glucose or sucrose in a ratio of 1:1 by weight and heated at 100°C for 0, 2, or 6 hr. Quality changes by the heat treatment were assessed by determining the extent of browning (browning index), in-vitro protein digestibility, available lysine total amino acids, and computed protein efficiency ratio (C-PER). Whereas the sucrose-containing complexes changed very little in all the quality parameters determined, the counterparts containing glucose decreased substantially in protein quality along with the increased intensity of browning. Before heating, protein digestibility of the complex containing defatted flour of an oilseed was lower than that of the isolate counterpart. When heated, however, the isolate-glucose complexes decreased more in protein digestibility than the flour-glucose complexes. The available lysine content decreased by 76-83% for the complexes with glucose in contrast with 2-10% for those with sucrose. As to total amino acids, marked losses in arginine, lysine, tryptophan, and histidine were found in the complexes containing glucose, with the arginine loss as high as the lysine loss. Lysine-rich soy proteins lost lysine in greater percentages than lysine-poor peanut and cottonseed proteins. C-PER decreased by 63-86% in the glucose-containing complexes, with the highest decrease shown for soy flour-glucose. In-vitro protein digestibility, available lysine, and C-PER were all highly correlated (P < 0.01) with browning index. Available lysine was also highly correlated with C-PER.     

芝麻饼粕蛋白质的理化和功能性质研究

对碱溶酸沉法、超声辅助碱提法和蛋白酶法3种工艺制备的芝麻饼粕蛋白质PA、PU和PE的理化和功能性质进行了研究,结果表明3种工艺制备的芝麻饼粕蛋白质氨基酸组成无显著差异,除赖氨酸含量较低外,其他必需氨基酸组成均接近或高于FAO/WHO模式;芝麻饼粕蛋白的相对分子质量大小顺序为PAPUPE。芝麻饼粕蛋白质的溶解性、持水性、持油性、乳化性、起泡性及起泡稳定性大小顺序为:PEPUPA,且芝麻饼粕蛋白质的p H-乳化性曲线与p H-溶解性曲线相似,溶解度和乳化性在等电点(p H 4)时最低。     

大豆分离蛋白的磷酸化改性研究

采用三聚磷酸钠 (STMP)对大豆分离蛋白 (SPI)进行磷酸化改性。研究了不同改性程度下SPI功能特性的变化。结果表明 :磷酸化SPI等电点由 pH 4 4 1移至pH 3 86,溶解性、乳化能力和持水性也有明显提高     

牛血浆蛋白凝胶特性研究

研究不同加工条件如蛋白浓度、加热温度、离子强度和pH对牛血浆蛋白凝胶特性的影响。结果表明:蛋白浓度的提高有利于凝胶的形成,且形成凝胶的最低血浆蛋白浓度是4.0%;4.8%的血浆蛋白,线性升温到85℃保温20 min,能够很好形成凝胶,呈果冻状,光滑有弹性;NaCl浓度在1.0 mol/L以下时,血浆蛋白凝胶强度随离子强度的变化是先增加后减小,0.3 mol/L时取得最佳效果;在pH6.0~9.0范围内,pH为9.0时牛血浆蛋白凝胶的凝胶强度较好,保水性高,蒸煮损失低。NaCl和pH对于牛血浆蛋白的凝胶特性有极显著的互作效应。     

干燥方式对不同接枝度的大豆分离蛋白-麦芽糊精聚合物性质影响

以大豆分离蛋白(SPI)和麦芽糊精(MD)为原料制备不同接枝度的SPI-MD聚合物,研究比较喷雾干燥和冷冻干燥两种处理方式对不同接枝度下的SPI-MD聚合物性质的影响,如溶解度、疏水性、持水性、乳化性、乳化稳定性及起泡性、泡沫稳定性等的影响。实验表明,喷雾干燥样品的溶解性,表面疏水性和乳化性高于冷冻干燥样品;冷冻干燥样品则具有较好的持水性。另外,两种干燥样品的乳化稳定性非常接近。不同接枝度的两种干燥样品起泡性差异较大,且泡沫稳定性都相对较差。     

Functionality of Flours, Protein Fractions and Isolates from Field Peas and Faba Bean

Field pca and faba bean proteins are rich sources of lysine, and air classification of the pin milled flours essentially doubled the protein contents in the protein fractions. The proteins in these flours and protein fractions were highly soluble at acid pH and exhibited only a narrow range of insolubility at pH 4–5. Water holding and oil absorption capacities increased in proportion to protein contents of the flour, protein fraction, and isolate of each legume, including soybean flour and isolate, but oil emulsification properties were uniformly high among all products. The protein fractions exhibited excellent whipp-ability and foam stability compared to soybean controls, and their promising functional properties suggested potential applications in meat emulsions, beverages and bakery products.     

Effect of extraction and isolation on physicochemical and functional properties of an underutilized seed protein: Gingerbread plum (Neocarya macrophylla)

The effect of extraction and isolation on the physicochemical and functional properties of gingerbread plum seed protein isolate was studied. Gingerbread plum seed protein isolate was extracted from defatted gingerbread plum seed flour (DGPSF) by alkali solution along with isoelectric precipitation. The protein isolate was subjected to freeze or vacuum drying process. Freeze dried gingerbread plum seed protein isolate (FGPSPI) and vacuum dried gingerbread plum seed protein isolate (VGPSPI) were evaluated for their physicochemical and functional properties (protein solubility, water/oil binding capacity, emulsifying capacity, foaming capacity). Among physicochemical parameters, the proximate composition, amino acid composition, minerals, differential scanning calorimetry (DSC), SDS-PAGE and color attributes were studied. Both FGPSPI and VGPSPI contained over 90% protein versus DGPSF (56.72%) used as raw material. The method of drying had significant effect (p < 0.05) on the physicochemical characteristics of FGPSPI and VGPSPI except for amino acids composition. The functional properties were variable among samples. DGPSF had higher emulsifying, water holding and oil binding capacities compared with FGPSPI and VGPSPI. FGPSPI exhibited better emulsifying capacity and water holding capacity than VGPSPI. FGPSPI also showed comparable oil binding capacity and bulk density to commercial soy protein isolate (SPI). The results indicated that FGPSPI and VGPSPI could be a good source of protein fortification for a variety of food products for protein deficient consumers as well as a potential food ingredient.     

Evaluation of functional properties of offal proteins

Evaluation of functional properties of beef heart and lip tissue proteins was based on the data obtained in the following determinations: protein extractability, fat emulsifying capacity, emulsion stability, gel forming ability, and water holding capacity after heat treatment. Beef skeletal muscles were used as the control. It was found that extractability of proteins of the raw materials was low as well as their ability to stabilize emulsions was on a low level. Proteins soluble at high ionic strength (fraction HIS) of beef heart and lip tissue emulsified 80.7 ml and 68.9 ml of oil/100 mg of protein, respectively, as compared to 106.6 ml in the control group. Analogically, protein soluble at low ionic strength (fraction LIS) emulsified 77.9 ml, 61.2 ml and 100.4 ml of oil, respectively. Emulsion stability of offal proteins appeared to be dependent on ionic strength. Generally at higher concentrations of salt their ability to stabilize emulsions was better as well as their water holding capacity increased. Their gelation properties as compared to control were also low. In each case, the functionality of cardiac proteins proved to be better than that of beef lip tissue.     

Effects of extrusion screw speed,feed moisture content,and barrel temperature on the physical,techno-functional,and microstructural quality of texturized lentil protein

Utilizing lentil protein as a novel ingredient for producing texturized vegetable proteins (TVPs) can provide new opportunities for the production of next-generation hybrid meat products. TVPs from lentil protein isolate were manufactured using low-moisture extrusion cooking at different combinations of screw speed (SS), feed moisture content (MC), and barrel temperature (BT) profile. In total, seven different combinations of processing treatments were tested, and the resulting TVPs were characterized for their physical (rehydration ratio, texture profile analysis, color, and bulk density), techno-functional (oil and water holding capacities), and microstructural properties. The processing conditions of higher SS and lower MC resulted in increased values of several textural profile attributes (springiness, cohesiveness, and resilience), increased water holding capacity (WHC), and decreased bulk density. Compared to raw lentil protein, TVPs showed enhanced oil holding capacity, though WHC either decreased or remained constant. The extrusion response parameters (die pressure, torque, and specific mechanical energy) showed positive correlations with several physical properties (texture, WHC, and total color change), revealing their potential for serving as important TVP quality indicators. TVPs produced at SS, MC, and BT of 450 rpm, 30%, and 140°C, respectively, showed relatively better overall physical and techno-functional quality and can be used as meat extenders in hybrid meat patties. Overall, this research evidenced the viability of lentil protein as a potential ingredient for producing low-moisture TVPs.