Chemical cross-linking and molecular aggregation of soybean protein during extrusion cooking at low and high moisture content

Soybean protein isolate (SPI) was extruded using a co-rotating twin-screw extruder at low (28%) and high (60%) moisture content. Dead-stop operation was employed to obtain samples from different zones of the extruder. The protein solubility of extrudate was analyzed based on 8 different combinations of chemical bond-breaking solutions, which contained only phosphate buffer (P); two reagents, i.e. sodium dodecyl sulfate (SDS) in P (P + S), urea in P (P + U) and 2-mercaptoethanol (2-ME) in P (P + M); three reagents, i.e. (P + S + U), (P + U + M) and (P + M + S); four reagents, i.e. (P + S + U + M). Based on the protein solubility in the combined extraction solutions, each specific chemical bond and their interactions responsible for supporting the extrudate structure were further analyzed. The aggregation of protein subunits in extruded sample was investigated by using SDS-PAGE electrophoresis. The results showed that hydrophobic interactions, hydrogen bonds, disulfide bonds and their interactions collectively hold the structure of extrudate; and the importance of non-covalent bonds outweighs covalent bonds. Increasing feed moisture content could increase the interactions between disulfide bonds and hydrogen bonds and between disulfide bonds and hydrophobic interactions (p < 0.05), reduce the degree of aggregation and the difference in protein-protein interactions and protein subunits among different zones within the extruder.     

System parameters and product properties response of soybean protein extruded at wide moisture range

In order to explore the effect of water during extrusion process, soybean protein isolate (SPI) was extruded using a pilot-scale twin-screw extruder at 28%, 36%, 44%, 52% and 60% moisture content and 140, 150 and 160 °C cooking temperature. The extrusion system parameters like in-line viscosity at die, mean residence time and specific mechanical energy (SME), product textural properties including tensile strength, hardness, chewiness and degree of texturization, and the molecular weight distribution characterized by SDS–PAGE were investigated. And the interrelationship between system parameters and product properties were analyzed. The results showed that moisture content was a more important factor on system parameters and product properties than cooking temperature. Higher moisture content resulted in lower viscosity of dough in the extruder, shorter residence time and lower conversion ratio of extruder mechanical energy into heat energy, finally reducing significantly the tensile strength, hardness, chewiness and the degree of aggregation. The data from extrusion system parameters and product properties correlate well and could be used to explain and control the characteristics of extrudate.     

花生蛋白挤压组织化及应用现状

该文综述花生蛋白挤压组织化原理、工艺流程、特点及组织化花生蛋白应用现状。     

大豆蛋白质原料体系对挤压组织化的影响

本文采用FTS-50型双螺杆挤压机,试验研究了复合大豆蛋白质原料体系中蛋白质含量、氮溶指数、油脂含量、淀粉含量和水分含量对挤压过程和产品组织化质量的影响研究结果表明,高蛋白质含量和高氮溶指数能促进挤压组织化作用,添加适量油脂和添加淀粉能促进挤压稳定性、组织质量和挤压产品的风味与口感,挤压产品(例如人造肉)的适当水分含量范围是60％—65％     

大豆蛋白挤压组织化加工影响因素及应用

大豆是我国重要的植物蛋白资源,而经过低温压榨取油后的豆粕是生产植物蛋白的重要原料。本文对大豆蛋白挤压组织化原理及特性、组织蛋白拉丝蛋白加工方法以及组织蛋白的种类应用进行了介绍,其中详细介绍了挤压膨化法加工组织蛋白的工艺流程及生产过程中原料、设备、工艺参数等对组织蛋白结构、弹性、吸水性的影响,最后对未来组织蛋白在仿真肉上应用的进行了展望。     

影响食品挤压膨化品质的因素及对策

通过分析影响食品挤压膨化度的因素，找出关键控制点，以提高产品膨化质量，提高制成率。     

Extrusion of food proteins.

Protein extrusion has frustrated earlier predictions regarding its impact in the development of food products. The main reason for this disappointing performance has been its failure to yield fabricated food products with textural quality close enough to that of natural products at competitive prices. Texturized soya protein by extrusion is presently the only commercial success in this area, being incorporated into several convenience products, increasing their protein content and quality and conferring them some desirable sensory properties. Technological and scientific gaps in the extrusion texturization are still to be bridged if this technique is to be applied for upgrading unconventional protein. The precise mechanisms responsible for protein texturization through extrusion are still unclear. Proteins show a very wide range of extrusion behavior that is probably related to large differences in their association properties. New peptide bonds, formed by free amino and carboxylic groups of the protein, were postulated as being responsible for the cross-linking that takes place in protein extrusion. However, disulfide bonds and electrostatic and hydrophobic interactions are regarded presently as the texturization mechanism in this process. The recently suggested suspension (or filled "melt") model for biopolymer extrusion offered a new framework for testing extrusion of novel proteins. According to this view, the large differences between the association properties of proteins produce different types of aggregates. Some of them can be insoluble under extrusion conditions and act as a dispersed phase within the melt phase. The extrusion performance of a protein will thus depend on the amount of insoluble aggregate produced inside the extruder and on protein-protein interactions that occur after the superheated molten mass leaves it.     

螺杆转速和原料含水率对糯米单螺杆挤出过程的影响

本文利用组合实验研究了糯米单螺杆挤出过程中操作参数(螺杆转速、原料含水率]对挤出设备和产品性能(生产率、功耗、度电产量、膨化指数、吸水指数、水溶性指数)的影响,建立了相互影响关系的回归方程,得出随螺杆转速的增加,生产率、功耗、水溶性指数增大,而度电产量、膨化指数、吸水指数开始上升,然后下降,存在极大值,综合各指标,该设备的最佳螺杆转速在240—260rpm;随原料含水率的增加,生产率、度电产量、吸水指数增加,而功耗、膨化指数、水溶指数减小,该设备挤出膨化糯米时的最佳原料含水率在18％～21％范围内。     

Effect of extrusion process on the antioxidant activity and total phenolics in a nutritious snack food

The effect of screw speed (220–340 rpm), moisture content of the feed (11.0–15.0%, wet base) and feed rate (22.0–26.0 kg h^?1, wet base) on the total antioxidant capacity (TAA) and concentration of total phenolics (TP) in a nutritionally balanced extruded snack were investigated. Regression equations describing the effect of each variable on the responses were obtained. Results indicated that screw speed, moisture content of the feed and feed rate had an effect on the TAA values of the samples at 95% confidence interval (CI). The interaction between the three factors was also found to be significant at 95% CI for TAA values. Extrusion conditions applied in this study did not change the TP values in the samples. The TAA value of samples decreased with an increase in screw speed and decrease in moisture content.     

纤维状仿肉制品的高湿挤压生产技术

目前，人们越来越关注利用双螺旋挤压机，在高湿度条件（水分含量40％-80％）下，把植物蛋白制成高纤维化的仿肉制品。与低湿度下生产蛋白产品不同的是，高湿条件下挤压出的蛋白有很好的纤维化结构，它类似于鸡肉或火鸡脯肉，因而提高了视觉效果和口感。这项技术大约有20年的发展历史，但只是到了近几年才开始出现商业化。为了满足消费者不断提高的对健康和美味食品的要求，这项技术已成为纤维化植物蛋白一个重要方法。     

高水分组织化花生蛋白产品干燥和复水特性研究

采用双螺杆挤压机研制的高水分组织化花生蛋白产品中(HM-TPP)蛋白质含量高,具有与动物肌肉类似的纤维状结构和口感,可作为食品原料和配料。文中主要分析了高水分组织化花生蛋白产品的干燥和复水特性。干燥试验结果表明:随干燥温度的增加制品中水分含量达到10%以下所需干燥时间明显缩短,在40、50和60℃下,分别需干燥4.5、7和13 h。其中,60℃下的干燥速率明显高于50℃和40℃下的干燥速率。干制HM- TPP产品的复水试验结果显示:在复水前期(1 h),水温40℃和60℃时的复水速率明显高于20℃的,但40℃和60℃的复水速率无明显区别。复水2.5～3.5 h后,复水产品中水分含量基本达到饱和状态。所得复水产品质地柔韧、表面光滑,富有弹性,基本可以恢复到新鲜产品的品质特性。     

稻米酶法制取超高纯度麦芽糖浆工艺研究

以稻米为原料,以耐高温α - 淀粉酶为液化酶,以真菌淀粉酶和普鲁兰酶两种糖化酶协同糖化,研究稻米高纯度麦芽糖浆制取技术。结果表明：控制液化值为14 左右,糖化时真菌淀粉酶和普鲁兰酶用量分别为0.6FAU/g 干米淀粉和0.3PUN/g 干米淀粉,糖化时间控制在18h 左右、糖化温度59℃、糖化pH5.5,可以制得麦芽糖含量85% 以上的超高麦芽糖浆。     

Effect of extrusion cooking on protein modification in wheat flour

Common soft wheat flour was extruded at three different temperatures and two different moistures. To investigate the dependence of the wheat protein modification on processing conditions, their solubilities in sodium dodecyl sulfate (SDS) were compared with those in SDS+(2-mercaptoethanol) ME. Furthermore, free sulfhydryl groups were detected with Ellmans Reagent and SDS-PAGE was performed under reducing and non-reducing conditions. The solubility values in SDS were greatly reduced after extrusion. The solubility values in SDS+ME were not affected. We therefore concluded that intermolecular cross-linking by disulfide bonding through extrusion cooking had occurred. This result was confirmed by SDS-PAGE under reducing and non-reducing conditions. At low and medium temperatures the solubilities were lower at low moisture; however, more free sulfhydryl groups were detected under these conditions, suggesting that moisture content of the flour has an influence on the way and the nature of the protein polymerization. At the highest thermal energy input at low moisture the solubilities increased again. This was accompanied by an increase of detectable free sulfhydryl groups. This led to the conclusion that disulfide bonds were cleaved at high energy input. The solubility development in 70% ethanol was nearly the same as in SDS. This is seen as a proof that gliadins are highly involved in the protein network formed under extrusion conditions. This finding was also confirmed by the results of SDS-PAGE.     

脱氟南极磷虾虾糜与大豆分离蛋白双螺杆挤压重组工艺研究

以冷冻南极磷虾为原料,制备一种平均氟含量为79.79 mg/kg干重的脱氟南极磷虾虾糜(AKS)。将脱氟虾糜与大豆分离蛋白(SPI)混合物料经双螺杆挤压作用进行蛋白质重组,以组织化度为指标,研究物料水分、机筒Ⅳ区加热温度、螺杆转速以及进料速度等工艺参数对组织化产品特性的影响,并用响应面分析优化工艺,得到虾糜-大豆分离蛋白组织化的最优工艺:混合物料水分为40%(虾糜:大豆分离蛋白=4:5),机筒一至四区的加热温度分别为70、90、120、140℃,螺杆转速为180 r/min,进料速度为30 kg/h,制备得到组织化度为2.18的暗红色条状组织化产物。     

Influences of extrusion parameters on physicochemical properties of textured vegetable proteins and its meatless burger patty

Isolated soy protein, wheat gluten, and starch at ratio 5:4:1 were texturized under different moisture contents (40 and 50%) and die temperature (130 and 150 °C) by the twin-screw extruder. Physicochemical properties were firstly studied. These textured vegetable proteins (TVPs) were used to form 100% plant-based burger patties. Cooking and textural features were secondly investigated. TVP at 50% moisture content and 130 °C die temperature represented the highest water absorption capacity and integrity index but the lowest solubility among TVPs. Cooking loss and shrinkage in diameter and thickness, cohesiveness, chewiness, hardness, and cutting strength of TVP meatless burger patties were significantly lower than that commercial meat patty, while moisture retention and springiness of TVP meatless burger patties were higher (p < 0.05). Our results found that the texture of patty made with TVP at 50% moisture content and 130 °C die temperature was the most similarity to commercial meat patty.     

高水分组织化复合蛋白的挤压制备及品质特性研究

以大豆分离蛋白、谷朊粉和豌豆蛋白为原料,采用高水分挤压技术制备组织化蛋白产品,研究了挤压参数对产品品质特性的影响,分别优化出以大豆分离蛋白和豌豆蛋白为主料的两种产品的配方及挤压参数。结果表明,水分添加量对产品品质特性影响显著;螺杆转速在280r/min,挤压温度在160℃时制备的产品具有较好的质构特性和拉丝效果;当大豆分离蛋白添加量40%,谷朊粉添加量35%,豌豆蛋白添加量25%,水分添加量14.0kg/h时,制得的组织化蛋白产品表面光滑,成型性好,可作为鸡肉仿肉制品;当豌豆蛋白添加量45%,谷朊粉添加量35%,大豆分离蛋白添加量20%,水分添加量13.5kg/h时,制得的组织化蛋白产品拉丝状态明显,质构特性指标与牛肉相似。     

大米淀粉制备麦芽糖浆的工艺研究

为降低高纯度大米蛋白的成本,采用碱提取法将大米蛋白及大米淀粉分离,大米淀粉用双酶法制备麦芽糖浆。结果表明：用大米粉联产大米蛋白和麦芽糖浆可以得到蛋白含量为90.58% 的大米分离蛋白;大米淀粉在pH5.71、温度102℃、时间15min 的α- 高温淀粉酶液化,pH5.00、温度58℃、时间10h 的真菌淀粉酶糖化条件下,得到含量为45.18% 麦芽糖的麦芽糖浆;同等条件下用大米粉制备的麦芽糖浆中的麦芽糖含量为40.83%。     

板粟深加工中淀粉的酶水解研究

试验对比了BAA中温α-淀粉酶和耐高温α-(Termamyl 120L,S型)对板栗浆液中淀粉的液化效果，选择使用耐高温α-淀粉酶(Termamyl 1120L，S型)为液化板栗淀粉的作用酶，单因素研究确定了液化工艺参数为：料水比1：5，液化温度90℃，pH6．0，酶用量7U／g果肉，液化时间60min。然后采用Novozym^TMAG糖化酶对液化后的板粟淀粉进行糖化，以淀粉水解度(DE值)和糖化液中还原糖的含量(g／100m1)为指标，正交试验表明，在糖化温度60℃，pH4．5，Novozym^TMAG使用量为80U／g果肉的条件下糖化90min，可使水解度(DE值)和糖化液中还原糖含量(g／100m1)分别达到48．9％和4．52g／100ml。     

红小豆粉液化及糖化条件研究

以红小豆为试验材料,采用单因素试验研究红小豆粉的液化糖化规律,优化液化糖化条件.结果表明,α-淀粉酶加量、糖化酶加量、液化温度、糖化温度以及pH值对红小豆液化、糖化的还原糖含量有显著影响.α-淀粉酶加量0.035％、60℃、pH值5时液化30min,还原糖含量为35.63mg,/mL.糖化酶加量0.9％、60℃、pH值4时糖化20h,还原糖含量显著提高,达到87.10mg/mL.糖化残渣电镜扫描观察结果表明红小豆淀粉己基本水解完全,为后续的发酵奠定了基础.