Miscibility,morphology, structure,and properties of porous cellulose–soy protein isolate hybrid hydrogels

Porous hybrid hydrogels were fabricated by mixing cellulose (CEL) and soy protein isolate (SPI) solutions, followed by crosslinking with epichlorohydrin. Their miscibility, morphology, structure, and properties were investigated by wide‐angle X‐ray diffraction, thermogravimetric analysis, scanning electron microscopy, dynamic mechanical analysis, rheological measurement, and swelling tests. The results show that CEL performed as a “scaffold” of pore walls and contributed to the good mechanical properties, while SPI performed the role of an “extender” of pore size and was responsible for the high water absorbency. The incorporation of CEL (stiff chains) and SPI (hydrophilic groups) in the hybrid hydrogel constructed the porous structure. This work provides a method for the fabrication of hydrogels with porous structure through the combination of a stiff material as a “scaffold” and a hydrophilic material as an “extender.” © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43853.     

神府煤对大豆分离蛋白质的吸附特性研究

采用静态吸附法探讨了神府煤粉(SFC)对大豆分离蛋白质(SPI)的吸附特性。研究了SPI溶液初始质量浓度(3.0—12.0 kg/m3)、温度(20、30、40、50℃)、pH值(4.0—9.0)等条件对吸附量的影响。结果表明,吸附平衡时间为12 h,适宜的pH值为6.0。SFC对SPI吸附过程为非自发的放热过程,吸附过程符合二级动力学模型。红外光谱分析表明,蛋白质分子主要通过C O和NH与煤大分子结构中的OH和C O对应形成2个活性位点的氢键作用,吸附于煤表面。     

Preparation and characterization of soy protein isolate films modified with sorghum wax

The effect of increasing the concentration of sorghum wax paste on the characteristics of soy protein isolate (SPI) films was investigated. Water vapor permeability (WVP), tensile strength (TS), elongation at break (E), and total soluble matter (TSM) of cast SPI films were determined. Sorghum wax paste extracted with ethanol was added to film-forming solutions of SPI at 5, 10, 15, or 20% w/w of protein. As the concentration of wax paste increased, mean WVP, E, and TSM values of SPI-sorghum-wax-paste composite films decreased and were lower than those of control SPI films. Mean TS values were lower than the control upon addition of 5 and 10% wax paste; however, TS values increased at 15 and 20% was concentrations. Although no differences in components of sorghum wax were observed between paste extracted with ethanol and wax extracted with hexane, paste extracted with ethanol was miscible with the filmforming solution. SPI-sorghum wax paste films had better water barrier and physical properties compared to control films.     

Graft polymerization of styrene on soy protein isolate

The grafting of styrene on soy protein isolate (SPI) in an 8 moL/L urea aqueous solution initiated by ammonium cerous nitrate and potassium persulfate was studied. The grafted copolymers were characterized by IR spectroscopy and DSC. The results indicated that styrene was grafted on the SPI. The influence of the reaction conditions on the grafting and efficiency percentages was investigated. The grafting and efficiency percentages initially increased and then decreased with the increase of the initiator concentration, monomer concentration, and reaction temperature. With the increase of reaction time, the grafting and efficiency percentages increased. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1457–1461, 2005     

甲基丙烯酸缩水甘油酯对大豆蛋白塑料改性作用研究

用模压的方法制备了甲基丙烯酸缩水甘油酯(GMA)改性大豆分离蛋白质(SPI)塑料。表征了GMA改性SPI塑料的力学性能、耐水性,并分析了GMA与SPI之间的相互作用。结果表明GMA在模压过程中,环氧基与蛋白质分子间发生接枝和交联反应,同时自聚,在GMA含量较低时可以同时对SPI塑料起到增强和增塑作用,但是随着GMA含量增加,交联作用增强,塑料的断裂伸长率下降。     

Preparation of soy protein concentrate and isolate from extruded-expelled soybean meals

Soy protein concentrates (SPC) and soy protein isolates (SPI) were produced from hexane-defatted soy white flakes and from two extruded-expelled (EE) soy protein meals with different degrees of protein denaturation. Processing characteristics, such as yield and protein content, and the key protein functional properties of the products were investigated. Both acid-and alcohol-washed SPC from the two EE meals had higher yields but lower protein contents than that from white flakes. Generally, SPC from an acid wash had much better functional properties than those from an alcohol wash. The SPI yield was highly proportional to the protein dispersibility index (PDI) of the starting material, so the EE meal with lower PDI had lower SPI recovery. The protein content in SPI prepared from EE meals was about 80%, which was lower than from white flakes. Nevertheless, SPI from EE meals showed functional properties similar to or better than those from white flakes. The low protein contents in SPC and SPI made from EE meals were mainly due to the presence of residual oil in the final products. SPI made from EE meals had higher concentration of glycinin relative to β-conglycinin than that from white flakes.     

Effect of lipids on soy protein isolate solubility

Reduced-lipid soy protein isolate (SPI), prepared from soy flour treated so that most of the polar lipids have been removed, exhibited an increase in protein solubility of 50% over that of the control SPI prepared from hexane-defatted flour. Adding lipids from a commercial SPI during processing of reduced-lipid SPI decreased SPI solubility by 46%. The 19% decreased solubility caused by the lipids (primarily phospholipids) was largely recovered by treating the protein with a reducing agent (2-mercaptoethanol). The balance of protein insolubility, caused by the lipids, was attributed to a smaller lipid fraction (approximately 5% of the total lipids). Adding lipids during SPI processing contributed to both the formation of oxidized protein sulfhydryls, incapable of being reduced by 2-mercaptoethanol, and to oxidative deterioration of protein as determined by protein carbonyl contents.     

Phosphorus flow in production of soy protein concentrate and isolate from defatted soybean flour

Implications of excess phosphorus (P) in waste streams obtained from soy-based protein preparation processes on the environment and their potential utilization as P-source are two significant understudied areas. Soybean-based protein ingredients for food products retain comparatively enhanced functional properties and are cheaper than other plant-based proteins. Soybean protein can be extracted and utilized as a food ingredient primarily by preparing soy protein concentrates (SPC) and soy protein isolates (SPI) from soybean meal/defatted soy flour (DSF). In a typical soybean processing facility, along with the soy products and soy-protein preparations, the recovery of phosphorus as a coproduct will enhance the economic feasibility of the overall process as the recovered P can be used as fertilizer. In this study, the SPC and SPI were prepared from the DSF following widely used conventional protocols and P flow in these processes was tracked. In SPC production, ~59% of the total P was retained with SPC and ~34% was in the aqueous waste streams. For SPI process ~24% of total P was retained with SPI and ~59% went in the waste solid residue (~40%) and aqueous streams (~19%). About 80%–89% P removal from the waste aqueous streams was achieved by Ca-phytate precipitation. This work demonstrated that in the process of SPC and SPI preparation the phosphorus from the waste aqueous streams can be precipitated out to avoid subsequent eutrophication and the waste solid residue with ~40% P can be reused as a P-fertilizer as other applications of this residue are unspecified.     

Influence of sorghum wax,glycerin, and sorbitol on physical properties of soy protein isolate films

Sorghum wax, sorbitol, glycerin, and soy protein isolate (SPI) composite films were prepared. Effects of sorghum wax, sorbitol, and glycerin concentrations on various films were evaluated using response surface methodology. All independent variables significantly (P<0.05) affected film water vapor permeability (WVP), tensile strength (TS), elongation at break (E), total color difference, and total soluble matter (TSM). Increasing the sorghum wax concentration decreased WVP and E. As sorbitol content increased in the composite films, WVP and TS increased. Sorbitol had a critical point of 2–5 g/5 g SPI for low values of TSM. The addition of sorbitol contributed more to the properties of the film than did glycerin.     

Effect of xanthan gum on enhancing the foaming properties of soy protein isolate

The foaming properties of soy protein isolate (SPI) in the presence of xanthan gum (XG) were investigated. The XG solution alone did not exhibit any foaming ability. The optimal foaming properties were obtained from the SPI-XG dispersion that contained 0.1% SPI and 0.2% XG. This SPI-XG dispersion gave higher foaming capacity than that of SPI or egg white (P<0.05). The foam stability of SPI-XG dispersion was nine times higher than that of SPI and egg white (P<0.05). The SPI-XG foams were stable over wide ranges of ionic strength (0.1 to 1.0 M NaCl) and pH (4.5 to 9.0), and when heated (85°C, 1 h).     

Blends of polylactic acid and arylated soy protein isolate with triacetine as plasticiser

Abstract

Blends of polylactic acid (PLA) and arylated soy protein isolate (ASPI) were successfully prepared by the extrusion process followed by injection moulding. To improve the interfacial adhesion between PLA and ASPI powder, mandelic acid as an amphiphilic additive was incorporated. Rheological and thermal characterisations of PLA/ASPI blends were performed on rheometer, differential scanning calorimeter and thermogravimetric analyser. Thermomechanical characterisation of PLA/ASPI blends was carried out on a dynamic mechanical analyser. Tensile and flexural modulus of PLA/ASPI blends increased compared to neat PLA. Different amounts (5–15 wt-% wrt PLA/ASPI blends) of plasticiser was added to PLA/ASPI blends containing 2·5 wt-% of ASPI. Results indicated that at 10 wt-% of plasticiser, PLA/ASPI blends showed maximum tensile strength of ～8·8 MPa as well as appreciable elongation at break. Morphological studies of PLA/ASPI blends at different amounts of plasticiser were also carried out by scanning electron microscope.     

pH‐sensitive alginate/soy protein microspheres as drug transporter

The complex microspheres based on alginate (AL) and soy protein isolate (SPI) were prepared by solution blending and then Ca²⁺ crosslinking, and their function as drug carrier was explored as well. The effects of composition on the structures of microspheres were studied, and the XRD results proved the miscibility between components. Meanwhile, FTIR results suggested that such miscibility was driven by strong hydrogen bonding. Especially, the complex microsphere with equal content of AL and SPI had the best miscibility by morphological analysis, shown as a smooth and uniform surface of SEM images. The controlled release function of the complex microspheres was verified using theophylline as a drug model, that is, the swelling and drug release were affected by pH conditions and showed obvious differences under given pH of stomach, intestine, and colon. Moreover, the intestine and colon may be optimal site for prompt release of drugs. Except for the attribution of AL component to pH sensitivity, the complex microspheres also inherited the bioactivity of SPI component, which may lower irritants of drug to the tissues in body. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Foaming and emulsifying properties of soy protein isolate and hydrolysates in skin and hair care products

There is a growing market for formulating proteins into a wide variety of products including laundry detergents, bath products, shampoos, and skin cleansers. Soy protein isolate (SPI), soy protein hydrolysate A (SPHA) from papainmodified SPI, and hydrolysate B from papain- and proteasemodified SPI were used in blends with three major detergents, sodium dodecyl sulfate (SDS), sodium laureth sulfate (SLS), and disodium lauryl sulfosuccinate (DSLSS). SPHA was used to partially replace these detergents in bath soap, conditioning shampoo, and cream hand cleanser. The effectiveness of SPI, SPHA, or SPHB blends with the three detergents and their influence in prototype products on foaming and emulsifying properties were investigated. At a blending ratio of 75% detergents and 25% proteins (75∶25), the foaming capacities (FC) were the same as detergents alone without adding proteins (100∶0); at 50∶50 blending ratio, FC values were not significantly reduced for blends with SDS and SLS; and at 25∶75 ratio the FC values were significantly lower, especially for blends with DSLSS. When replacing up to 100% of the major detergents in the skin and hair care products with SPHA, FC values remained almost unchanged except for hand cleanser FC values, which were lower at higher protein content (75 and 100%). In contrast with FC performance, emulsion stability (ES) values for all products increased with increasing soy protein content. Furthermore, FC and ES values for detergents blended with SPHA or SPHB were not significantly different from each other, but these values were always higher than those for detergents blended with SPI. Products in which soy protein or soy protein hydrolysates were used to partially replace detergents not only retained excellent foaming properties but also exhibited enhanced emulsifying properties. These results indicate that modified soy proteins may be used in laundry and cosmetic products to fulfill market demand.     

PVAc乳胶/改性大豆分离蛋白共混胶黏剂的制备及性能

针对大豆蛋白胶黏剂耐水性差的缺点,用尿素初步改性大豆分离蛋白（SPI）,然后与白乳胶（PVAc）共混合成了共混改性大豆分离蛋白胶黏剂。采用正交实验方法考察了大豆蛋白胶与白乳胶质量比、共混时间、交联剂质量分数、交联时间对大豆蛋白胶黏剂剪切粘接强度的影响,确定了优化配比及制备工艺条件,并在此基础上采用正交试验优化了热压参数。结果表明：大豆蛋白胶与白乳胶质量比10∶1,共混时间1h,交联剂质量分数1.0%,交联时间1.5h,热压温度120℃,热压压强1.2MPa,热压时间2min/mm,涂胶量250g/m2时,测得胶黏剂的干态剪切粘接强度为2.01MPa,按照Ⅰ类胶合板标准测得湿态剪切粘接强度为1.04MPa,并对优化配方进行了结构与性能分析。     

Interaction of soy isolate with polysaccharide and its effect on film properties

When soy isolate was mixed with sodium alginate, the two polymers interacted to form electrostatic complexes. They also formed varying degrees of covalent bonding, depending on reaction time and the presence or absence of the reducing agent sodium cyanoborohydride. On the other hand, soy isolate and propyleneglycol alginate (PGA) formed mostly covalent complexes at alkaline pH. The interaction of soy protein with polysaccharide maintained or improved its solubility and emulsifying activity, particularly when covalent bonds were involved. The alkylated complexes also showed better film-making properties. However, protein-PGA films were more readily formed and had greater stability in water than the protein-alginate films.     

Effect of pro-oxidants on the occurrence of 2-pentyl pyridine in soy protein isolate

Levels of 2-pentyl pyridine in hexane-defatted soybean flours prepared from Burlison, Stressland, and Probst varieties and a variety null for lipoxygenase 1, 2, and 3 were determined using an internal standard of deuterium-labeled 2-pentyl pyridine. These defatted flours contained from 0.06 to 0.51 ppm 2-pentyl pyridine. The flours from lipoxygenase-null and Stressland varieties of soybeans contained the lowest levels. Control freeze-dried soy protein isolates (SPI) prepared from defatted-flours all contained from 0.16 to 0.18 ppm 2-pentyl pyridine. Adding pro-oxidants (FeCl₃, CuCl₂) or exposing the protein slurries to ultraviolet light during SPI processing increased the level of 2-pentyl pyridine in the protein isolates by up to 1256 percent above the control Burlison, Stressland, and Probst SPI. The CuCl₂ and/or UV treatment contributed the largest increase in each case. The same pro-oxidant and UV treatments contributed no significant increases in the level of 2-pentyl pyridine in the protein isolates from the lipoxygenase null SPI.     

Adhesion properties of soy protein with fiber cardboard

Adhesion properties of soy protein isolate (SPI) on fiber cardboard and effects of press conditions, pre-pressing drying time, and protein concentrations on gluing strength were investigated. Shear strength increased as press time, press pressure, and/or press temperature increased. The effect of temperature on shear strength became more significant at high press pressure. The shear strength of the SPI adhesive on fiber cardboard decreased by 12–25% after water soaking. Shear strength increased as pre-pressing drying time increased and reached its maximal value at about 10 min. An SPI/water ratio of 12∶100 (w/w) gave the highest gluing strength. The specimens showed complete cohesive failure (fiber cardboard failure) except for soaked specimens pressed at low press temperature, low pressure, and short press time. Specimens pressed at 25°C and 2 MPa for 5 min with pre-pressing drying time of 10 min and an SPI/water ratio of 12∶100 (w/w) had T-peel strength and tensile bonding strength of 1.15 N/mm and 0.62 MPa, respectively, without water soaking, and 1.11 N/mm and 0.24 MPa, respectively, with water soaking.     

Enhancement of discharged energy density of poly(ethylene oxide) by soy protein isolate

Soy protein isolate (SPI) is used to modify energy storage performances of poly(ethylene oxide) (PEO). The pure PEO membranes are highly polar, but the extremely high energy loss led to very low discharged energy density for use. The addition of SPI in both high molecular weight PEO and low molecular weight PEO lead to greatly reduced polarization and stored energy density. However, it also largely reduces the current leakage and energy loss of the resulting membranes, leading to significantly enhanced discharged energy density. It is believed that the strong interactions between PEO and SPI are responsible for the energy storage properties aforementioned. Meanwhile, such interactions also result in a more brittle fracture behavior and reduced crystallinity of the PEO/SPI membranes. The enhanced discharged energy density and low energy loss suggest PEO/SPI membranes are promising dielectric materials for high efficiency energy storage applications where soluble and transient materials are desired. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45214.     

改性大豆蛋白胶粘剂的研究进展

天然高分子大豆蛋白有着一些卓越的功能特性，可以用作胶粘剂。而改性大豆蛋白胶粘剂功能特性更优越。近几十年，作为环境友好绿色化工产品，改性大豆蛋白胶粘剂的研究与应用开发均取得了很大的进展，综述了大豆蛋白改性技术、改性大豆蛋白胶粘剂的特性及其应用。     

Properties of molded soy protein isolate plastics

Thermal property of soy protein isolates (SPI) was studied with differential scanning calorimetry and thermogravimetric analysis. The weight loss of pure SPI is about 300°C. The glass transition temperature (T_g) is above 200°C. The best molding temperature of glycerin plasticized SPI plastics were then given. It is between 125 and 140°C. Subsequently the special property of molded SPI plastics was investigated. Results show that the atmosphere humidity affects the mechanical property and thermal property of SPI plastics. With the increasing humidity, the tensile strength decreases. While the elongation at breakage and peak area of the differential scanning calorimetry curve increases. At high temperature even at 140°C the molding temperature SPI plastics still have tensile strength though it decreases with the increasing test temperature while elongation at breakage increases. Dynamic mechanic thermal analysis test show that the storage modulus decreases with the rising temperature. The mechanical loss peak appears at lower temperature with the increasing amount of glycerin content. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007