Protein-Protein Interactions in the Extrusion of Soya at Various Temperatures and Moisture Contents

Soya protein isolate extruded at various temperatures and moisture contents was solubilized before and after processing in buffers containing urea, sodium disulphite, 2-mercaptoethanol, sodium dodecyl sulphate, alone or in combination to elucidate stabilizing mechanisms for their three dimensional structure. The main mechanisms were disulphide linkages, hydrophobic and electrostatic interactions. All extrudates resisted retorting in water at 120°C but complete disruption occurred in media containing reducing agents plus sodium dodecyl sulphate. Little change in amino acid occurred in extrusion except for aspartic and glutamic acids, which decreased in extrusion at 140°C. Infrared spectra showed the presence of β-sheet anti parallel structures. Peptide bonds were of negligible importance in extrusion texturization of soya protein. If formed they only contributed to an insoluble phase in the melt.     

Texturized mung bean protein as a sustainable food source: Effects of extrusion on its physical,textural and protein quality

Despite being inexpensive and a sustainable source of plant protein, mung bean remains underutilized due to its hard-to-cook characteristics. The aim of this study is to produce texturized mung bean protein (TMBP) with desirable physical properties, through optimization of extrusion parameters determined as follows: 49.33% feed moisture, 80.66 rpm screw speed and 144.57 °C barrel temperature. Under these conditions, all physical properties (expansion ratio, bulk density, rehydration ratio, water absorption capacity and degree of texturization) are desirably altered. Microstructure analysis reveals fibrous structure that is aligned along the shear flow direction in TMBP while SDS-PAGE shows partial protein unfoldment that is crucial for protein fibril formation during texturization. Amino acid profile shows high retention of amino acids after texturization. Current study successfully demonstrates the optimized production of TMBP from mung bean protein with strong potential as meat extender to serve as a healthier option compared to animal proteins.Industrial relevanceCurrent work is conducted on a pilot-scale basis, from initial protein extraction up to final extrusion step. This allows food industry to readily adapt the processing parameters, as detailed in current work, for customized production of texturized mung bean protein.     

双螺杆食品挤压蒸煮研究的进展

本文综述了双螺杆食品挤压蒸煮研究的进展,包括大豆蛋白的挤压组织化机理、流变性能、挤出理论、挤出机头和食品挤出试验的系统分析模型,主要是针对大豆蛋白质物料。     

Texturized Dairy Proteins

ABSTRACT: Dairy proteins are amenable to structural modifications induced by high temperature, shear, and moisture; in particular, whey proteins can change conformation to new unfolded states. The change in protein state is a basis for creating new foods. The dairy products, nonfat dried milk (NDM), whey protein concentrate (WPC), and whey protein isolate (WPI) were modified using a twin-screw extruder at melt temperatures of 50, 75, and 100 °C, and moistures ranging from 20 to 70 wt%. Viscoelasticity and solubility measurements showed that extrusion temperature was a more significant (P < 0.05) change factor than moisture content. The degree of texturization, or change in protein state, was characterized by solubility (R²= 0.98). The consistency of the extruded dairy protein ranged from rigid (2500 N) to soft (2.7 N). Extruding at or above 75 °C resulted in increased peak force for WPC (138 to 2500 N) and WPI (2.7 to 147.1 N). NDM was marginally texturized; the presence of lactose interfered with its texturization. WPI products extruded at 50 °C were not texturized; their solubility values ranged from 71.8% to 92.6%. A wide possibility exists for creating new foods with texturized dairy proteins due to the extensive range of states achievable. Dairy proteins can be used to boost the protein content in puffed snacks made from corn meal, but unmodified, they bind water and form doughy pastes with starch. To minimize the water binding property of dairy proteins, WPI, or WPC, or NDM were modified by extrusion processing. Extrusion temperature conditions were adjusted to 50, 75, or 100 °C, sufficient to change the structure of the dairy proteins, but not destroy them. Extrusion modified the structures of these dairy proteins for ease of use in starchy foods to boost nutrient levels. Practical Application: Dairy proteins can be used to boost the protein content in puffed snacks made from corn meal, but unmodified, they bind water and form doughy pastes with starch. To minimize the water binding property of dairy proteins, whey protein isolate, whey protein concentrate, or nonfat dried milk were modified by extrusion processing. Extrusion temperature conditions were adjusted to 50, 75, or 100 °C, sufficient to change the structure of the dairy proteins, but not destroy them. Extrusion modified the structures of these dairy proteins for ease of use in starchy foods to boost nutrient levels.     

植物蛋白高水分挤压组织化技术的现状及发展

结合国内外相关文献对高水分蛋白挤压技术的研究进行总结,并将挤压机作为生物反应器,以此为基础系统论述了大豆蛋白、小麦蛋白等植物蛋白原料的高水分挤压组织化技术.在总结过程中,对高水分挤压技术的发展历程、高水分挤压设备、挤压机理、相关的技术特点等方面进行论述,探讨了植物蛋白高水分挤压过程中蛋白质特性的变化以及相关的挤压系统参数对挤压蛋白产品组织结构的影响,并阐述了这项技术的研究动态及发展前景.     

挤压对大豆蛋白构象及其组织化结构的影响研究进展

随着挤压技术的发展,以大豆蛋白为主要原料经过挤压加工制成具有明显组织化结构的素肉制品技术以及蛋白组织化结构形成机制越来越受到学者的关注.近几年的研究表明大豆蛋白微观结构的变化对大豆素肉的宏观组织化结构具有至关重要的作用.本文对挤压过程中大豆蛋白构象及其对组织化结构影响的研究进行综述,概述大豆蛋白分子构成,并总结了挤压对...     

挤压对谷物蛋白的微观结构和功能特性影响的研究进展

谷物蛋白是丰富的蛋白质资源之一,谷物挤压加工在新型食品创制中得到大量应用.研究谷物蛋白在挤压过程中的微观结构和功能特性的影响机理,对促进谷物蛋白类产品加工的创新开发具有重要意义.本文分析挤压对谷物蛋白的微观结构的影响,综述了谷物蛋白在挤压过程中,一级结构不发生变化;二级结构未被完全破坏,构象之间存在相互转化;三级结构发...     

植物蛋白原料体系影响挤压组织化研究进展

蛋白原料是挤压生产组织化产品的基础,只有适宜的蛋白原料配以合适的挤压操作工艺,才能生产出满足要求的组织化蛋白产品。通过归纳国内外相关文献资料,从蛋白原料种类、蛋白质含量、蛋白质变性程度、蛋白质组分和结构以及蛋白原料中其他共存成分5大方面,系统分析影响植物蛋白挤压过程和产品特性的因素;指出不同类别蛋白原料的复配挤压以及原料制备工艺,蛋白质组成、蛋白质改性和添加剂等对挤压产品特性的影响,可能是植物蛋白挤压组织化领域将来的研究热点和方向。     

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％     

磷脂与食品中蛋白质相互作用机制及对蛋白质特性的影响研究进展

食品中磷脂与蛋白质的相互作用一直是食品领域研究的热点。蛋白质是食品组分中具有重要生理功能的物质,其功能特性和结构的变化对食品品质影响较大。磷脂是一种有效的天然乳化剂,是重要的两性离子表面活性剂,已广泛用于食品加工中。磷脂与蛋白质通过疏水相互作用、氢键等方式结合,进而影响蛋白质的结构和功能特性。本文对食品中大豆蛋白、酪蛋白、乳清蛋白、肌原纤维蛋白等蛋白质与磷脂相互作用机制、影响因素及其对蛋白质功能特性的影响进行综述,以期为磷脂改善蛋白质的功能特性和提高食品品质提供参考。     

Physical properties, molecular structures, and protein quality of texturized whey protein isolate: effect of extrusion moisture content

To explore the complex relationship between processing conditions and functional and nutritional properties of food products containing whey protein isolate (WPI), we investigated the effect of extrusion texturization at various temperatures (50, 75, and 100°C) and varying moisture levels of the feed (20, 30, 40, and 50%) on changes in the composition, molecular structure, and protein quality of the extrudates. Bradford assay methods were used to determine protein solubility of the extruded WPI as a function of changing level of moisture. Protein compositional changes as a function of extrusion conditions were quantitatively characterized and analyzed by sodium dodecyl sulfate-PAGE and reversed-phase-HPLC techniques. We showed that at a given temperature, increasing the extrusion moisture content resulted in a slight increase in the overall protein water solubility (at 50 and 75°C), averaging approximately 5% per 10% increase in moisture content. A reduction in β-lactoglobulin content was observed at 50°C with increasing moisture content, indicative of the sensitive nature of β-lactoglobulin to extrusion treatment, whereas the amount of α-lactalbumin remained unchanged at all moisture contents used at a set temperature. The protein quality of the extruded WPI, determined chemically by available sulfhydryl and primary and secondary amines, remained relatively unchanged as a function of moisture level. Circular dichroism and intrinsic tryptophan fluorescence spectroscopic studies revealed considerable structural changes, both at the secondary structural level and the tertiary contacts as a function of increasing temperature, and higher moisture levels can slightly preserve secondary structures but not the tertiary contacts of the protein molecules. Atomic force microscopy provided direct visualization of the fine difference of the protein particles caused by changing extrusion moisture contents, which is in close agreement with the results obtained using other techniques in this work.     

Effect of protein–starch interactions on starch retrogradation and implications for food product quality

Starch retrogradation is a consequential part of food processing that greatly impacts the texture and acceptability of products containing both starch and proteins, but the effect of proteins on starch retrogradation has only recently been explored. With the increased popularity of plant-based proteins in recent years, incorporation of proteins into starch-based products is more commonplace. These formulation changes may have unforeseen effects on ingredient functionality and sensory outcomes of starch-containing products during storage, which makes the investigation of protein–starch interactions and subsequent impact on starch retrogradation and product quality essential. Protein can inhibit or promote starch retrogradation based on its exposed residues. Charged residues promote charge–dipole interactions between starch-bound phosphate and protein, hydrophobic groups restrict amylose release and reassociation, while hydrophilic groups impact water/molecular mobility. Covalent bonds (disulfide linkages) formed between proteins may enhance starch retrogradation, while glycosidic bonds formed between starch and protein during high-temperature processing may limit starch retrogradation. With these protein–starch interactions in mind, products can be formulated with proteins that enhance or delay textural changes in starch-containing products. Future work to understand the impact of starch–protein interactions on retrogradation should focus on integrating the fields of proteomics and carbohydrate chemistry. This interdisciplinary approach should result in better methods to characterize mechanisms of interaction between starch and proteins to optimize their food applications. This review provides useful interpretations of current literature characterizing the mechanistic effect of protein on starch retrogradation.     

Interactions between plant proteins/enzymes and other food components,and their effects on food quality

Plant proteins are the main sources of dietary protein for humans, especially for vegetarians. There are a variety of components with different properties coexisting in foodstuffs, so the interactions between these components are inevitable to occur, thereby affecting food quality. Among these interactions, the interplay between plant proteins/enzymes from fruits and vegetables, cereals, and legumes and other molecules plays an important role in food quality, which recently has gained a particular scientific interest. Such interactions not only affect the appearances of fruits and vegetables and the functionality of cereal products but also the nutritive properties of plant foods. Non-covalent forces, such as hydrogen bond, hydrophobic interaction, electrostatic interaction, and van der Waals forces, are mainly responsible for these interactions. Future outlook is highlighted with aim to suggest a research line to be followed in further studies.     

Solid‐State Protein–Carbohydrate Interactions and Their Application in the Food Industry

The growing interest in food component interactions, especially the solid‐state protein–carbohydrate ones, has led to a growing body of knowledge on the effects of these interactions on the physical, chemical, and structural properties of compositionally complex food systems. The goal of the present review is to survey the critical mechanisms involved in protein–carbohydrate interactions as a key step toward the rational formulation and processing of protein‐ and carbohydrate‐rich foods to produce products with desirable properties without adverse reactions. The hypotheses proposed on the stabilizing effects of carbohydrates on proteins and the role of different types of sugars in the extent of these interactions are reviewed in this article. Another aspect of this review involves the successful drying of proteins by spray‐drying, freeze‐drying, and supercritical‐fluid‐drying using carbohydrates. Finally, applications of these interesting phenomena to produce important food products including milk powder, infant formulas, bakery products, and fruit and vegetable juice powders are investigated.     

组织化大豆蛋白生产工艺研究与应用进展

组织化大豆蛋白是大豆蛋白加工业中重要产品之一。梳理组织化大豆蛋白生产工艺及其关键技术,可提升产品质量和种类,促进大豆蛋白加工业的稳定发展。本研究整理、阐述组织化大豆蛋白生产工艺,以及涉及的关键技术、质量评价、食品应用等方面的研究进展。组织化大豆蛋白具有动物蛋白纤维状结构和咀嚼感,替代动物蛋白可以降低生产成本,改善膳食结构。蛋白质含量、纤维状结构、持水性、色泽是组织化大豆蛋白的质量要素。挤压组织化大豆蛋白产业目前仍以普通组织化蛋白产品为主,开始规模化生产纤维状结构明显的拉丝蛋白,而高水分组织化蛋白仍停留在试验阶段。     

食品中蛋白质的功能(六) 食品中蛋白质的功能性质(三)——大豆蛋白和小麦蛋白

大豆蛋白和小麦面筋蛋白都是优良的植物蛋白,具有多种独特的功能性质,对改善制品的感官和食用品质有较好作用,广泛应用于食品领域。本文分别对大豆蛋白和小麦蛋白的特性以及在各类食品中的应用进行了较为全面的综述。     

Texture and rehydration properties of texturised soy protein: analysis based on soybean 7S and 11S proteins

Soy protein, one of the most commonly used raw materials for texturised vegetable protein, has an important influence on texturised soy protein (TSP) with its 7S and 11S fractions. In this study, soy 7S and 11S proteins were extracted from soybean isolate and added back to the raw material to prepare TSP and analyse the effect of both on the physical properties of TSP. The results showed that the addition of 5% soy 7s or 11s protein increased the water-holding capacity (up to 9.04%) and rehydration rate (up to 25.71%) of TSP. Compared with adding soy 11s protein, adding soy 7s protein has a faster rehydration rate at a lower temperature (30 and 45 °C). After extrusion, the content of free sulphhydryl groups, total sulphhydryl groups, and disulphide bonds was significantly reduced (P < 0.05). The extrusion treatment caused degradation of the protein chains, and the proteins mainly formed insoluble polymers. Electrophoretic analysis revealed that the sodium dodecyl-sulphate (SDS) reducing the extractable rate of the precipitate after SDS non-reduction extraction of the TSP added with 5% soy 7S and 11S proteins were lower than that of the control. The proportion of different soybean protein components in TSP could change its texture, water-holding, and rehydration characteristics of it, which provides a new method for the characteristics design of TSP.     

海藻酸钠添加对大豆浓缩蛋白植物肉特性的影响

以大豆浓缩蛋白为原料，添加不同比例海藻酸钠并改变模头温度，利用双螺杆高水分挤压技术制备植物肉。通过组织化度、咀嚼度、颜色、扫描电子显微镜等指标表征植物肉的宏观结构和微观结构。通过比机械能、蒸煮特性、吸水率评价植物肉的结构性能。结果表明，海藻酸钠的添加可以提高植物肉的组织化度，增强咀嚼性。并且在模头温度为150 ℃时，所有挤压样品具有较好的组织化特性。比机械能和吸水率表明，海藻酸钠增强了蛋白质-蛋白质、蛋白质-水之间的相互作用，得到的植物肉持水性升高。扫描电子显微镜表明，过量的海藻酸钠会使产品形成致密的层状而非纤维状结构。因此，海藻酸钠添加量为6%时，通过高水分挤压技术可制备组织化程度高，蒸煮效果较好的大豆浓缩蛋白挤压植物肉产品。     

Rheological Properties of Extruded Milk Powders

Whey protein concentrate, whey protein isolate, and nonfat dry milk may be processed through a twin-screw extruder to produce ingredients for protein-fortified food. The products ranged from rigid to flexible to soft, and small amplitude oscillatory shear measurements showed that these properties varied with extrusion temperature and moisture content. The whey proteins showed different effects than nonfat dry milk due to the type and amount of protein present. The characteristics of extruded milk powders can be manipulated through processing parameters to obtain texturized products with the desired rheological properties.     

INFLUENCE of 7S and 11S GLOBULINS ON the EXTRUSION PERFORMANCE of SOY PROTEIN CONCENTRATES

The 7S and 11S fractions of soy protein were isolated from soy flour and recombined with soy protein concentrate at various levels to modify their ratio in different formulations. the role of each fraction on the extrusion performance and texturization behavior of soy proteins was evaluated using twin-screw extrusion. Both 11S and 7S fractions were found to have significant influence on the degree of texturization of soy protein. In particular, the 11S protein appeared to favor expansion and water holding capacity of the finished product, while an 11S/7S ratio of 1.5 in the feed formulation resulted in a product with the best textural characteristics under the selected extrusion conditions investigated.