低温储藏条件对大豆分离蛋白膜理化特性的影响

以大豆分离蛋白为原料制得可食性膜,研究在不同低温储藏条件下其功能特性,包括机械性能和阻隔性能的变化。结果显示:随冷藏温度的升高,其功能特性变化较为缓慢。而随冻藏温度的降低,断裂延伸率下降尤为明显,抗拉强度和脂质阻隔能力变化趋势次之,水蒸气透过率升高缓慢。冷藏时间与断裂延伸率呈显著正相关(p<0.05)。冷藏时间与水蒸气透过率和油脂渗透系数均呈极显著正相关(p<0.01)。冻藏时间与水蒸气透过率和油脂渗透系数呈显著正相关(p<0.05)和极显著正相关(p<0.01)。     

大豆分离蛋白和油炸条件对面包虾品质的影响

以裹粉率、水分损失率、吸油量、色泽以及质构等为考察指标,研究了油炸温度、油炸时间以及在以小麦粉为主体的裹浆粉中添加大豆分离蛋白对深度油炸面包虾品质的影响。结果表明:大豆分离蛋白能显著增加面包虾的裹粉率(P<0.05),降低油炸产品的水分损失量和吸油量(P<0.01)。在相同的油炸条件下,添加10%大豆分离蛋白的处理组的面包虾的吸油量最低。油炸温度和时间对面包虾的水分损失、吸油量、色泽以及质构产生极显著的影响(P<0.01),随着油炸温度的升高和时间的延长,面包虾的水分损失和吸油量均增加。此外,在170℃条件下油炸4 min,面包虾的脆性最好。     

超声波对大豆分离蛋白物理改性的研究

研究了超声循环处理对大豆分离蛋白的乳化性、起泡性和表面疏水性的影响。结果表明,当处理1600mL浓度为1％大豆分离蛋白溶液时,与未经超声处理的蛋白相比,超声功率320W,超声时间15min,乳化能力提高了17％,乳化稳定性提高了49％;在超声时间15min、超声功率为960W、800W时,大豆分离蛋白的起泡能力和起泡稳定性分别达到最大,比未经超声处理的蛋白分别提高了70％和7％;当超声功率640W时,大豆分离蛋白的疏水性达到最大,与未经超声处理相比提高了39％。     

盐对可食性大豆分离蛋白膜亲水性影响的研究

在大豆分离蛋白(SPI)膜中添加NaCl、Na2CO3、Na2S2O3、Na3PO4、Na4P2O7、ZnCl2和FeCl3,通过研究膜的水分含量(WC)、可溶性干物质(TSM)、水蒸气透过系数(WVP)及其动态接触角(DCA)系统考察盐对SPI膜亲水性的影响。结果表明:NaCl和FeCl3使得SPI膜的WC分别增加7.4%和15.5%,Na4P2O7、Na2S2O3、Na3PO4、Na2CO3和ZnCl2分别使WC减少18.8%、18.9%、3.8%、7.6%和16.1%;NaCl和Na2S2O3使SPI膜的TSM略有增加,但Na3PO4、Na2CO3、Na4P2O7、ZnCl2和FeCl3使TSM分别降低32.3%、13.7%、7.1%、12.7%和23.9%;Na3PO4、Na4P2O7、Na2CO3和Na2S2O3及ZnCl2分别使WVP增加88.9%、51.4%、36.5%、28.7%和21.0%,NaCl不改变膜的WVP,而FeCl3使膜的WVP值略有下降;NaCl、Na2CO3、Na2S2O3和FeCl3使SPI膜在极性和非极性溶剂中的DCA均降低,而Na3PO4、Na4P2O7和ZnCl2使得SPI膜在极性和非极性溶剂中的DCA均提高。     

大豆分离蛋白对湿米粉储藏品质的影响

以湿米粉储藏过程中硬度、蒸煮损失和断条率的变化为指标,研究大豆分离蛋白对湿米粉品质的影响。结果表明,大豆分离蛋白会导致湿米粉硬度的升高,但在储藏过程中添加大豆分离蛋白的湿米粉硬度低于未添加大豆分离蛋白的湿米粉,这表明大豆分离蛋白可显著改善湿米粉在储藏过程中的硬度升高现象;当大豆分离蛋白添加量低于4%时,湿米粉的蒸煮损失和断条率均随大豆分离蛋白添加量的增加而下降;但大豆分离蛋白添加量达6%时,湿米粉的蒸煮损失和断条率上升。结果表明适量的大豆分离蛋白可改善湿米粉的食用品质,但大豆分离蛋白添加量不是越多越好。差示热量扫描和微观结构分析发现大豆分离蛋白可抑制湿米粉中淀粉的回生,赋予米粉蜂窝状多孔结构,有利于米粉在储藏过程中保持水分不发生迁移从而提高湿米粉品质。     

淀粉-聚乙烯醇-大豆蛋白改性蒙脱土复合薄膜的结构与性能研究

通过大豆蛋白对天然蒙脱土进行改性,制备淀粉-聚乙烯醇-大豆蛋白改性蒙脱土复合薄膜。利用X射线衍射(XRD),透射电子显微镜(TEM)分析其结构,并且对复合薄膜的机械性能和水蒸气阻隔性能进行了研究。结果表明,当蒙脱土经大豆蛋白改性,黏土层之间的分子间力降低;淀粉、聚乙烯醇、黏土层间的相容性增加,这导致黏土片层在聚合物基质中更好的分散,形成了剥离程度较高的纳米结构。纳米结构的形成,使淀粉/聚乙烯醇薄膜水蒸气透过性显著下降,拉伸强度增加,断裂伸长率下降。     

储藏条件对大豆分离蛋白溶解性的影响

大豆分离蛋白被广泛应用于食品工业,但在贮运过程中其功能特性可能会发生变化。本研究将包装后的大豆分离蛋白(SPI)分别在RH80%、30℃,RH65%、25℃,RH55%、4℃,冷冻条件(RH90%,-18℃)和自然环境条件下储藏3个月,研究储藏环境、时间、包装条件对SPI溶解性的影响。结果表明,高湿条件(RH=80%,30℃)会加速SPI变性,促使溶解性随储藏时间的延长而下降;氮气能够提高SPI的溶解性,但是随储藏时间的延长溶解性仍会下降;在相同储藏条件和包装材料下,充气包装内气体比例为60%N2∶40%CO2,有利于提高或保持SPI的溶解性;冷冻条件能够使SPI改性,提高SPI的溶解性。     

Effects of ultrasound on structural and physical properties of soy protein isolate (SPI) dispersions

The effects of low-frequency (20 kHz) ultrasonication at varying power (200, 400 or 600 W) and time (15 or 30 min) on functional and structural properties of reconstituted soy protein isolate (SPI) dispersions were examined. Ultrasonic treatments reduced both the storage modulus and loss modulus of SPI dispersions and formed more viscous SPI dispersions (fluid character). Moreover, ultrasound treatment significantly decreased the consistency coefficients and increased the flow behaviour index of SPI dispersions. Scanning electron microscopy of lyophilized ultrasonicated SPI showed different microstructure with larger aggregates compared to non-treated SPI. No significant change was observed in the protein electrophoretic patterns by SDS-PAGE. However, free sulfhydryl content, surface hydrophobicity and protein solubility of SPI dispersions were all increased with ultrasonic treatment. Differences in solubility profiles in the presence versus absence of denaturing (0.5% sodium dodecyl sulphate and 6 M urea) and reducing (mercaptoethanol) agents suggested a decrease in non-covalent interactions of SPI in dispersion after ultrasonic treatment. Secondary structure analysis by circular dichroism indicated lower α-helix and random coil in SPI treated at lower power, in contrast to higher α-helix and lower β-sheet in SPI treated with higher power (600 W). In conclusion, under the conditions investigated in this study, ultrasonic treatment resulted in partial unfolding and reduction of intermolecular interactions as demonstrated by increases in free sulfhydryl groups and surface hydrophobicity, leading to improved solubility and fluid character of SPI dispersions, while larger aggregates of ultrasonic-treated SPI in the dry state were formed after lyophilization.     

大豆分离蛋白与谷朊粉可食性复合膜研究

该文报道影响大豆分离蛋白与谷朊粉复合膜成膜因素,分析各种因素对复合膜性能影响,并对正交试验结果采用极差分析和综合评分法进行评定,得到制备综合性能良好的可食性膜最佳条件为:谷朊粉与大豆分离蛋白比例为1∶5,甘油量为20%,pH为11,预热处理温度和时间分别为80℃和40min;此时,膜的透光率、拉伸强度、撕裂强度、水分含量和水蒸汽透过率依次为60.5%、38.38MPa、198.02N/mm、13.87%和0.507g·mm/kPa·h·m2。     

离子强度对大豆分离蛋白结构及表面疏水性的影响

旨在采用生物化学和光谱学方法及手段,从蛋白质分子空间构象和溶液性质角度,探讨离子强度对大豆分离蛋白结构及表面疏水性的影响机制。研究表明:大豆分离蛋白表面疏水性在等电点两侧呈现显著下降趋势,而随着离子强度的增大大豆分离蛋白表现出\     

Internal quality and shelf life of eggs coated with oils from different sources

Selected internal quality and shelf life of eggs coated with oils from differences sources (mineral oil, canola oil, corn oil, grape seed oil, olive oil, soybean oil, and sunflower oil) were evaluated during 5 wk of storage at 25 °C. As the storage time increased, weight loss increased whereas Haugh unit and yolk index values decreased. Throughout the 5 wk of storage, eggs coated with oils, regardless of oil sources, possessed better albumen and yolk quality than the control noncoated eggs. Oil coating minimized weight loss of eggs (<0.8%) compared with that (7.26%) of the noncoated eggs after 5 wk of storage at 25 °C. No significant differences in internal quality (weight loss, Haugh unit, yolk index, and albumen pH) were generally observed among oil-coated eggs during 5 wk of storage. Based on the Haugh unit, the grade of noncoated eggs changed from AA at 0 wk to A at 1 wk and to B after 3 wk whereas that of oil-coated eggs from AA at 0 wk to A at 4 wk and maintained A grade until 5 wk. This study demonstrated that oil coating, irrespective of oil sources, preserved the internal quality, minimized weight loss (<0.8%), and extended the shelf life of eggs by at least 3 wk longer than observed for the noncoated eggs at 25 °C storage. Soybean oil was a more practical option as a coating material for eggs due to its low cost. PRACTICAL APPLICATION: Eggs are highly perishable and susceptible to internal quality deterioration when stored above 7 °C. Refrigeration of eggs may be seldom practiced in some developing regions of the world. Therefore, an alternative method, that is inexpensive yet effective, to preserve the internal quality of eggs and to prevent microbial contamination is needed. Oil coating has been proven to preserve the internal quality, prolong shelf life, and minimize weight loss of eggs. This study demonstrated that, compared with other vegetable oils, soybean oil was a more practical option as a coating material for eggs during 5 wk of storage at 25 °C due to its low cost.     

糖基化改性对大豆蛋白抗原性及结构特性的影响研究

本文以大豆分离蛋白和葡聚糖为原料,在干热条件下进行美拉德反应,制取不同时间下的糖基化复合物。以β-伴大豆球蛋白和大豆球蛋白抗原抑制率为指标,采用间接竞争ELISA方法测定糖基化产物的抗原性,在反应6 d时,糖基化产物中β-伴大豆球蛋白和大豆球蛋白的抗原性分别降低了31.94%和21.26%。糖基化产物颜色加深,且游离氨基含量降低,说明大豆蛋白与糖发生了不同程度的反应。红外光谱中糖链的引入,使蛋白质分子展开,β-转角和无规则卷曲结构含量的降低,影响了β-伴大豆球蛋白α亚基的抗原表位,从而可能使大豆蛋白的抗原性降低。糖基化反应影响抗原性的关键作用在于蛋白与糖结合部位对蛋白质结构的变化。     

Mechanical and barrier properties of biodegradable soy protein isolate-based films coated with polylactic acid

Polylactic acid (PLA)-coated soy protein isolate (SPI) films were prepared by dipping SPI film into PLA solution. The effects of coating on improvements in mechanical and water barrier properties of the film were tested by measuring selected film properties such as tensile strength (TS), elongation at break (E), water vapor permeability (WVP), and water solubility (WS). TS of SPI films increased from 2.8±0.3 up to 17.4±2.1 MPa, depending on the PLA concentration of the coating solution, without sacrificing the film's extensibility. In contrast, the extensibility of SPI film coated with solution containing more than 2 g PLA/100 ml solvent, increased. WVP of PLA-coated SPI films decreased from 20 to 60 fold, depending on the concentration of PLA coating solution. Water resistance of SPI films was greatly improved as demonstrated by the dramatic decrease in WS for PLA-coated films. The improvement in water barrier properties was mainly attributed to the hydrophobicity of PLA.     

Preparation and characterization of bio-nanocomposite films based on soy protein isolate and montmorillonite using melt extrusion

The non-biodegradable and non-renewable nature of plastic packaging has led to a renewed interest in packaging materials based on bio-nanocomposites (biopolymer matrix reinforced with nanoparticles such as layered silicates). Bio-nanocomposite films based on soy protein isolate (SPI) and montmorillonite (MMT) were prepared using melt extrusion. Effects of the pH of film forming solution, MMT content, and extrusion processing parameters (screw speed and barrel temperature distribution) on the structure and properties of SPI–MMT bio-nanocomposite films were investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) were used for structural characterization of the films. Properties of the films were determined by tensile testing, dynamic mechanical analysis (DMA), thermogravimetric analysis (TGA), and water vapor barrier measurement. The arrangement of MMT in the soy protein matrix ranged from exfoliated at lower MMT content (5%) to intercalated at higher MMT content (15%). There was a significant improvement in mechanical (tensile strength and percent elongation at break) and dynamic mechanical properties (glass transition temperature and storage modulus), thermal stability, and water vapor permeability of the films with the addition of MMT. The results presented in this study show the feasibility of using bio-nanocomposite technology to improve the properties of biopolymer films based on SPI.     

蛋清蛋白、大豆分离蛋白及其美拉德反应产物膜包裹对核桃仁脂质过氧化作用的比较研究

本文通过测定核桃油酸价、过氧化值、丙二醛含量、碘值和DPPH自由基清除率五个指标的变化研究比较蛋清蛋白膜、大豆分离蛋白膜及其与木糖美拉德反应产物膜包裹对核桃仁脂质过氧化的影响。结果表明,随着反应时间（0⁸d）的增加,核桃仁酸价、过氧化值和丙二醛含量均呈现上升趋势,DPPH自由基清除率均呈现下降趋势,而碘值则变化不明显。加热第8d时,四种膜包裹核桃仁的酸价、过氧化值和丙二醛含量均小于未包膜的核桃仁,DPPH自由基清除率高于未包膜的核桃仁。四种膜包裹核桃仁的酸价无显著性差异（p>0.05）;而过氧化值中以蛋清蛋白膜组较高,且其余三组的无显著性差异（p>0.05）;四种膜包裹核桃仁的丙二醛含量均明显低于未包膜组,延缓丙二醛含量上升的效果依次为:大豆分离蛋白-木糖膜>蛋清蛋白-木糖膜>大豆分离蛋白膜>蛋清蛋白膜;大豆分离蛋白-木糖膜包裹核桃仁保留的DPPH自由基清除率明显高于其它三种膜。综上所述,两种蛋白及其美拉德反应产物膜包裹均可延缓核桃仁脂质过氧化,综合各项指标其效果依次为:大豆分离蛋白-木糖膜>蛋清蛋白-木糖膜>大豆分离蛋白膜>蛋清蛋白膜。      

大豆分离蛋白及其美拉德反应产物成膜条件探究

本论文研究不同p H（10、11、12）、不同加热温度（70、80、90℃）和不同甘油浓度（0³.0 m L/100 m L）对浓度为6 g/100 m L大豆分离蛋白溶液及大豆分离蛋白-葡萄糖（w/w=1）美拉德反应溶液、大豆分离蛋白-木糖（w/w=1）美拉德反应溶液成膜条件的影响。通过测定大豆分离蛋白-葡萄糖/木糖溶液的色差值及吸光值来判断美拉德反应程度,通过肉眼和手感观察和评价膜的可揭性、颜色和表观特征。实验结果表明:当大豆分离蛋白和糖浓度均为6 g/100 m L的条件下,大豆分离蛋白的成膜条件为甘油浓度:2.5 m L/100 m L、溶液p H11、80℃加热60 min;大豆分离蛋白与木糖美拉德反应产物成膜条件为甘油浓度:0.125 m L/100 m L、溶液p H11、80℃加热60 min;而大豆分离蛋白与葡萄糖在此条件下美拉德反应程度不明显,因此未对其进行膜的制备。      

环氧基交联剂对可食性大豆分离蛋白膜性能的影响

为了提高可食性大豆分离蛋白膜的性能,加入环氧基交联剂,考察了环氧基交联剂不同添加量对蛋白膜性能的影响。结果表明,环氧基交联剂的加入,可使大豆分离蛋白膜的机械性能增加显著,蛋白膜机械性能与交联剂的加入量显著关联。3种溶剂(甲苯、四氯化碳、四氢呋喃)溶胀实验表明,在实验条件下交联剂加入量在0.4~0.5 g时,蛋白膜交联程度较为理想。     

Glycation of soy protein isolate with two ketoses: d-Allulose and fructose

Modification of food proteins to have improved functional properties is of great importance. In this study, modification of soy protein isolate (SPI) was achieved through glycation. SPI was glycated in a spray dryer (SD) and an incubator followed by freeze drying (FD). d -Allulose, an important rare sugar, was used in SPI glycation as the carbohydrate source, and results were compared with fructose. In addition to the sugar type, two different SPI powder: sugar ratios (1:1 and 5:1) were investigated. For the glycated samples, emulsification activity, free amino groups, protein solubility, Fourier-transform infrared spectroscopy analysis, antioxidant activity experiments and time-domain NMR relaxometry measurements for hydration were conducted. According to the results, the solubility of SPI that is limited in native form has shown a significant improvement after glycation through both FD and SD methods. Besides, glycation through the FD method was found to be more favourable due to its milder conditions than the SD method. Considering the physicochemical properties, the best combination for the highest glycation degree was found to be the samples prepared at the 1:1 ratio with d -Allulose in the FD method. Overall, it was concluded that glycation of SPI enhanced its functional properties such as antioxidant and emulsification activities.     

pH和AOT添加物对大豆分离蛋白基可降解膜机械性能影响

运用响应面分析法分析pH和AOT(琥珀酸二异辛酯磺酸钠)添加物对大豆分离蛋白(SPI)基生物可降解膜机械性质影响,确定影响该种膜机械性能最优工艺参数;测试膜机械性质,包括抗拉强度、穿刺强度、断裂伸长率;分析结果表明,在pH为8.95,AOT添加量为13.00%(w/w)时,膜综合机械性能达到最优。     

十二烷基磺酸钠(SDS)在大豆分离蛋白基可食性膜中应用

该文报道研究十二烷基磺酸钠应用于以甘油作为增塑剂的大豆蛋白基可食性膜后对其物理性质影响。研究结果表明:当SDS添加量为40%(十二烷基磺酸钠质量/大豆分离蛋白质量)时,薄膜抗拉强度(TS)值显著(p<0.05)减少43%,最大断裂伸长率(E)值显著(p<0.05)增加至少5%,水分含量(MC)值显著减少(p<0.05),总可溶性物质含量(TSM)值显著增加(p<0.05);当SDS添加量>10%时,WVP值下降50%;SDS添加量为20%、30%、40%时,膜颜色值为显著+b (p<0.05),即黄色值增加。