Wheat Seed Proteins: Factors Influencing Their Content,Composition, and Technological Properties,and Strategies to Reduce Adverse Reactions

Wheat is the primary source of nutrition for many, especially those living in developing countries, and wheat proteins are among the most widely consumed dietary proteins in the world. However, concerns about disorders related to the consumption of wheat and/or wheat gluten proteins have increased sharply in the last 20 years. This review focuses on wheat gluten proteins and amylase trypsin inhibitors, which are considered to be responsible for eliciting most of the intestinal and extraintestinal symptoms experienced by susceptible individuals. Although several approaches have been proposed to reduce the exposure to gluten or immunogenic peptides resulting from its digestion, none have proven sufficiently effective for general use in coeliac‐safe diets. Potential approaches to manipulate the content, composition, and technological properties of wheat proteins are therefore discussed, as well as the effects of using gluten isolates in various food systems. Finally, some aspects of the use of gluten‐free commodities are discussed.     

Gluten weight in ancient and modern wheat and the reactivity of epitopes towards R5 and G12 monoclonal antibodies

Differences in the level of coeliac‐active gluten epitopes in wheat might have some significance for individuals reporting noncoeliac gluten sensitivity. The aim of this study was to compare the reactivity of epitopes towards ELISA R5 and G12 monoclonal antibodies in ancient (emmer; Khorasan wheat; spelt) and modern wheat (common bread wheat; durum), and to check whether the bread‐making process leads to the degradation of epitopes. Data from ELISA R5 and G12 did not match gluten dry weight in wheat. Bread dough fermentation and extensive baking did not change the reactivity of coeliac‐active epitopes towards monoclonal antibodies. Compared to hexaploid bread‐type wheat (spelt; common bread wheat), ancient and modern pasta‐type tetraploid wheat (emmer; Khorasan; durum) had less epitopes reactive towards ELISA R5 and G12 and might be preferable for wheat‐sensitive individuals looking for food with reduced coeliac‐active epitopes.     

Protein Characteristics that Affect the Quality of Vital Wheat Gluten to be Used in Baking: A Review

The use of vital wheat gluten in the baking industry and wheat flour mills aims to improve the rheological characteristics of flour considered unsuitable to obtain products such as sliced bread, French bread, high‐fiber breads, and other products that require strong flours. To improve characteristics such as flour strength, dough mixing tolerance, and bread volume, vital wheat gluten is added to flour at levels that can vary from 2% to 10% (flour basis), with 5% being a commonly used dosage. However, the vital wheat gluten commercialized in the market has few quality specifications, especially related to the characteristics of the proteins that constitute it and are responsible for the formation of the viscoelastic gluten network. Information on protein quality is important, because variations are observed in the technological quality of vital wheat gluten obtained from different sources, which could be associated to damage caused to proteins during the obtainment process. Several tests, either physical–chemical analyses, or rheological tests, are carried out to establish gluten quality; however, they are sometimes time‐consuming and costly. Although these tests give good answers to specify gluten quality, flour mills, and the baking industries require fast and simple tests to evaluate the uses and/or dosage of vital gluten addition to wheat flour. This review covers the concepts, uses, obtainment processes, and quality analysis of vital wheat gluten, as well as simple tests to help identify details about protein quality of commercial vital wheat gluten.     

Effects of edible plant polyphenols on gluten protein functionality and potential applications of polyphenol–gluten interactions

Expanding plant‐based protein applications is increasingly popular. Polyphenol interactions with wheat gluten proteins can be exploited to create novel functional foods and food ingredients. Polyphenols are antioxidants, thus generally decrease gluten strength by reducing disulfide cross‐linking. Monomeric polyphenols can be used to reduce dough mix time and improve flexibility of the gluten network, including to plasticize gluten films. However, high‐molecular‐weight polyphenols (tannins) cross‐link gluten proteins, thereby increasing protein network density and strength. Tannin–gluten interactions can greatly increase gluten tensile strength in dough matrices, as well as batter viscosity and stability. This could be leveraged to reduce detrimental effects of healthful inclusions, like bran and fiber, to loaf breads and other wheat‐based products. Further, the dual functions of tannins as an antioxidant and gluten cross‐linker could help restructure gluten proteins and improve the texture of plant‐based meat alternatives. Tannin–gluten interactions may also be used to reduce inflammatory effects of gluten experienced by those with gluten allergies and celiac disease. Other potential applications of tannin–gluten interactions include formation of food matrices to reduce starch digestibility; creation of novel biomaterials for edible films or medical second skin type bandages; or targeted distribution of micronutrients in the digestive tract. This review focuses on the effects of polyphenols on wheat gluten functionality and discusses emerging opportunities to employ polyphenol–gluten interactions.     

Novel Approaches in Gluten‐Free Breadmaking: Interface between Food Science,Nutrition, and Health

The evidence that celiac disease is one of the commonest food intolerances in the world is driving an increasing demand for gluten‐free foods. However, gluten is a structure‐building protein essential for formulating leavened baked goods. Therefore, obtaining high‐quality gluten‐free bread (GFB) is a technological challenge. This review focuses on contemporary approaches in gluten‐free baking that allow improvements at the structure, texture, acceptability, nutritive value, and shelf life of GFB. Gluten‐free breadmaking is a relatively new, emerging research topic that is attracting worldwide attention in order to develop different kinds of GFB, including regional varieties. Several approaches have been used to understand and improve GFB systems by evaluating different flours and starch sources, ingredients added for nutritional purposes, additives, and technologies or a combination of these elements. Some studies aimed to assess or improve GFB's technological or nutritional properties, while others had multiple objectives. Several studies used food science tools in order to improve technological and sensory quality of GFB, together with nutritional value. Some GFBs are vehicles of nutrients and bioactive compounds. Furthermore, extensive research on interfacing food science, nutrition, and health is needed so that a GFB with both good technological and nutritional properties can be prepared and made more available to those with celiac disease, which will help them adhere to a strict gluten‐free diet, increase social inclusion, and improve their quality of life.     

Adverse Reactions to Wheat or Wheat Components

Wheat is an important staple food globally, providing a significant contribution to daily energy, fiber, and micronutrient intake. Observational evidence for health impacts of consuming more whole grains, among which wheat is a major contributor, points to significant risk reduction for diabetes, cardiovascular disease, and colon cancer. However, specific wheat components may also elicit adverse physical reactions in susceptible individuals such as celiac disease (CD) and wheat allergy (WA). Recently, broad coverage in the popular and social media has suggested that wheat consumption leads to a wide range of adverse health effects. This has motivated many consumers to avoid or reduce their consumption of foods that contain wheat/gluten, despite the absence of diagnosed CD or WA, raising questions about underlying mechanisms and possible nocebo effects. However, recent studies did show that some individuals may suffer from adverse reactions in absence of CD and WA. This condition is called non‐celiac gluten sensitivity (NCGS) or non‐celiac wheat sensitivity (NCWS). In addition to gluten, wheat and derived products contain many other components which may trigger symptoms, including inhibitors of α‐amylase and trypsin (ATIs), lectins, and rapidly fermentable carbohydrates (FODMAPs). Furthermore, the way in which foods are being processed, such as the use of yeast or sourdough fermentation, fermentation time and baking conditions, may also affect the presence and bioactivity of these components. The present review systematically describes the characteristics of wheat‐related intolerances, including their etiology, prevalence, the components responsible, diagnosis, and strategies to reduce adverse reactions.     

Effects of Enzymatic Hydrolysis of Protein on the Pasting Properties of Different Types of Wheat Flour

Abstract: As one of the most effective methods to modify proteins, enzymatic hydrolysis is used widely in the preparation of wheat products in the food industry. During the same process, starch pasting occurs frequently. The effects of wheat protein hydrolysis with papain, pepsin, and trypsin on the pasting properties of 3 different kinds of flour were investigated in 5 concentrations. Results showed that the peak viscosity, trough, final, and integral area of pasting curve of these flours decreased with increasing enzymatic hydrolysis of protein, and decreased significantly with the increasing enzyme concentrations. Medium‐gluten flour was the least sensitive to enzymatic activity and weak‐gluten the most sensitive. Downtrends appeared with increasing papain and trypsin concentrations in the form of breakdown. Enzymes had no significant different effect on the peak times of strong‐ and medium‐gluten flour, but prolonged peak time slightly in weak‐gluten flour. The pasting time and temperature of strong‐ and medium‐gluten flour were significantly increased in a concentration‐dependent manner. However, there were no significant effects on the pasting times of weak‐gluten flour. These results could supply a basis for utilization of enzymatic hydrolysis of wheat protein in food industry and for further studies into the interactions between hydrolyzed protein and starch in food or processing industries. Practical Application: Illuminating the effects of enzymatic hydrolysis of protein on the pasting properties of different types of wheat flour is very important in food industry. Flour viscosity decreases after enzymatic hydrolysis of protein/gluten. Enzymes have different effects on peak time, pasting time, and pasting temperatures for different types of flour. These results could supply a basis for utilization of enzymatic hydrolysis of wheat protein in food industry and for further studies into the interactions between hydrolyzed protein and starch in food or processing industries.     

Non‐Celiac Gluten Sensitivity: How Its Gut Immune Activation and Potential Dietary Management Differ from Celiac Disease

Non‐celiac gluten sensitivity (NCGS) is a clinical entity triggered by the ingestion of gluten‐containing grains leading to intestinal and/or extraintestinal symptoms that resolve once the gluten‐containing foodstuff is eliminated from the diet, and it is diagnosed when celiac disease (CD) and wheat allergy (WA) have been ruled out. The limited knowledge about the pathophysiology of NCGS and the lack of validated biomarkers are still major limitations for clinical studies, making it difficult to differentiate NCGS from other gluten‐related disorders (GRD). In the absence of clear‐cut diagnostic criteria, NCGS is still mainly a diagnosis of exclusion. Several studies suggest that NCGS is an immune‐mediated disease that likely activates an innate immune response. Moreover, it has recently been hypothesized that in addition to gluten, other components of wheat may be responsible for the symptoms observed in individuals without CD. This review aims at discussing available evidence related to the histological and immunological features in the gut mucosa of patients with NCGS and at outlining new dietary opportunities for these patients.     

Assessment of the gluten toxicity of wheat and naan in Xinjiang Uyghur Autonomous Region,China

Xinjiang is a high-risk area for celiac disease (CD) regardless of genetic or environmental factors. However, no case has been reported yet in people living in Xinjiang. This study aims to explore the potential connection between diet and occurrence of CD in the Xinjiang population. To this end, the levels of T-cell stimulatory epitopes in 164 accessions of Xinjiang wheat were tested by using Western blot with monoclonal antibodies against α-gliadin epitopes Glia-α9 and Glia-α20. Three wheat varieties with remarkably low amounts of T-cell stimulatory epitopes were obtained. Western blot and R5 competitive ELISA were performed for the assessment of potential toxicity related to CD of naan. Results showed a reduction of gluten toxicity after wheat flour was processed into naan, suggesting it may have the potential to help to reduce the risk of CD for the genetically predisposed individuals.     

Effect of acetic acid deamidation‐induced modification on functional and nutritional properties and conformation of wheat gluten

BACKGROUND: Acids are often used for deamidating proteins, but the literature on acetic acid deamidation of proteins is sparse. Previous research on acetic acid‐induced modification of proteins has focused on peptide proteolysis by relatively high concentrations of acetic acid (>1.5 mol L^?1) rather than on the accompanying effect of deamidation. Therefore the objective of this study was to determine the deamidation effect of acetic acid with as little peptide proteolysis as possible by employing low‐concentration acetic acid (<0.05 mol L^?1) to deamidate wheat gluten. Changes in surface hydrophobicity, conformation, functional properties and nutritional characteristics of acetic acid‐modified samples were determined and compared with those of hydrochloric acid (HCl)‐modified samples. RESULTS: At similar degree of deamidation and nitrogen solubility index, samples deamidated with acetic acid showed less destruction of peptides bandings, better foaming properties and a more decompacted form (lower S? S content in protein as determined by Raman spectroscopy) than those deamidated with HCl and also exhibited improved emulsification capacity and emulsion stability compared with native wheat gluten. Acetic acid deamidation led to fewer changes in peptide molecular size and secondary structure of wheat gluten compared with HCl deamidation according to the results of sodium dodecyl sulfate polyacrylamide gel electrophoresis and Fourier transform infrared spectroscopy respectively. Amino acid analysis revealed that the nutritional characteristics of wheat gluten were well maintained after deamidation with acetic acid. CONCLUSION: The results show that low‐concentration acetic acid can modify wheat gluten mainly by deamidation, resulting in deamidated wheat gluten with good functional and nutritional properties. Copyright © 2009 Society of Chemical Industry     

A finer screening of wheat cultivars based on comparison of the baking potential of whole‐grain flour and white flour

Between 2007 and 2009, 160 wheat samples were harvested at four growing locations in Quebec (Eastern Canada) and evaluated individually for their performance in whole‐grain bread (all grain fractions) and white bread prepared with a long‐fermentation process (3 h). Combination of results from both baking tests allowed the most complete evaluation of the gas retention capacity of wheat samples. Compared to cultivar and crop year, growing location had a minor effect on the overall bread making potential of wheat samples. In whole‐grain bread, the four winter wheat lines had a poorer performance than the twenty‐one spring wheat cultivars. Little correlation was seen between dough mixing stability and gas retention properties. Determination of strong gluten content (dry gluten × gluten index) might be a useful screening tool for early‐generation wheat cultivars.     

Hearth bread baking quality of durum wheat varying in protein composition and physical dough properties

Thirty durum wheat genotypes from ten countries of origin were grown in field plots for two consecutive years. Three of the genotypes were γ‐gliadin 42 types and the remainder were γ‐gliadin 45 types. Among the γ‐gliadin 45 types, six high‐molecular‐weight glutenin subunit (HMW‐GS) patterns were identified: 6 + 8, 7 + 8, 7 + 16, 14 + 15, 20 and 2*, 20. All the γ‐gliadin 42 genotypes contained low amounts of unextractable polymeric protein (UPP) and exhibited low gluten index values and weak gluten properties. The γ‐gliadin 45 genotypes exhibited a wide range of UPP, gluten index and dough strength. HMW‐GS 20 genotypes were generally weak, whereas HMW‐GS 6 + 8 and 7 + 8 genotypes were generally strong. When baked by a lean formulation, long‐fermentation straight‐dough hearth bread process, the durum wheat genotypes exhibited a wide range of baking quality. Loaf volume and bread attributes were strongly correlated with UPP and gluten index. Some of the genotypes exhibited bread attributes and loaf volume equal or slightly superior to those of a high‐quality bread wheat flour. However, even the strongest durum wheat genotypes exhibited inferior fermentation tolerance to the bread wheat flour, as seen by a requirement for lower baking absorption during dough handling and more fragile dough properties when entering the oven. Among the HMW‐GS groups, HMW‐GS 7 + 8 and 6 + 8 exhibited the best and HMW‐GS 20 the poorest baking quality. Farinograph, alveograph and small‐scale extensigraph properties demonstrated that a combination of dough elasticity and extensibility was needed for superior durum wheat baking performance. Copyright © 2007 Society of Chemical Industry     

小麦在华南地区浅圆仓储藏过程中的品质特性变化

本文研究了小麦在华南地区浅圆仓储存过程中品质特性的变化。研究结果表明：随着储藏时间的延长,小麦水分,面筋含量、面筋吸水量和发芽率均呈下降趋势;而小麦降落数值、面团形成时间、拉伸面积、拉伸阻力及最大拉伸阻力、拉伸比例及最大拉伸比例均呈上升趋势,说明在长期的储存过程中小麦的品质发生了一定的变化。高温高湿的华南地区浅圆仓储存小麦安全储藏水分为12．5％,浅圆仓常规储存安全水分小麦,轮换周期可以适当延长至扯5年。     

Wheat gluten–based coatings and films: Preparation,properties, and applications

Effective food packaging that can protect foodstuffs from physical, chemical, and biological damage and maintain freshness and quality is essential to the food industry. Wheat gluten shows promise as food packaging materials due to its edibility, biodegradability, wide availability, low cost, film-forming potential, and high resistance to oxygen. The low mechanical properties and poor water permeability of wheat gluten coatings and films limit their wide applications; however, some inferior properties can be improved through various solutions. This work presents a comprehensive review about wheat gluten–based coatings and films, including their formulation, processing methods, properties, functions, and applications. The mechanical and water resistance properties of coatings and films can be reinforced through wheat gluten modification, combinations of different processing methods, and the incorporation of reinforcing macromolecules, antioxidants, and nanofillers. Antioxidants and antimicrobial agents added to wheat gluten can inhibit microbial growth on foodstuffs, maintain food quality, and extend shelf life. Performances of wheat gluten–based coatings and films can be further improved to expand their applications in food packaging. Current research gaps are identified. Future research is needed to examine the optimal formulation and processing of wheat gluten–based coatings and films and their performance.     

面筋蛋白粒子-黄原胶Pickering乳液的制备及其表征

制备黄原胶与面筋蛋白纳米粒协同稳的Pickering乳液,表征Pickering乳液的物理化学性能和微观结构。结果显示：通过黄原胶与面筋蛋白纳米粒协同作用,可制备出稳定性较好的Pickering乳液。低质量分数的黄原胶（0.2%）会促进乳析;当黄原胶质量分数不小于0.3%时,乳液于4 ℃贮存30 d仍无乳析现象;当黄原胶质量分数为1%时,贮存30 d乳液出现析油的现象。不同乳化顺序得到乳液的稳定性不同。乳液M-WG-XG（面筋蛋白纳米粒与玉米油乳化得粗乳液,然后加入黄原胶二次分散）的稳定性最好,同时乳液的平均粒径最小（21.4±0.314）μm。黄原胶的加入增大了乳液的净电荷,乳液的稳定性提高。共聚焦显微镜结果表明,乳液M-WG-XG液滴分布均匀,界面层呈现出多层结构。相比于其他方式制备的乳液,乳液M-WG-XG有更好的黏弹性和离子稳定性。     

苦荞粉面团流变学特性的研究

面团流变学特性对于确定焙烤食品的加工工艺及相关的工艺数据有重要的指导意义。本实验研究了苦荞粉的流变学特性,发现苦荞粉不适宜单独加工焙烤食品,必须添加适量的辅料。通过添加不同比例的谷朊粉可不同程度地改善苦荞粉面团的流变学特性,进而改变其加工特性。     

Application of Capillary Electrophoresis to Determine the Technological Properties of Wheat Flours by a Glutenin Index

ABSTRACT:  Capillary electrophoresis was used to characterize glutenin proteins from ancient varieties of Southern Italy common wheat and to determine the technological properties of wheat flours based on a glutenin index. Three zones were identified in the electropherograms, indicated as A, B, and C according to electroelution order. The three zones corresponded to the low molecular weight glutenin subunits and to the y- and x-type high molecular weight subunits, respectively. The ratio B/C was correlated to the alveographic parameter P/L. These results indicated that flours resulting in a B/C ratio lower than 2 produced elastic doughs whereas flours resulting in a B/C ratio higher than 2 produced doughs more resistant to extension. This study showed that capillary electrophoresis is useful for determining the types and quantities of gluten proteins in the evaluation of wheat-flour technological properties of a limited number of noncommercial varieties as evidenced by the x-type content which seems to strongly influence the flour technological parameters.     

小麦面筋蛋白结构及其改性研究

小麦面筋蛋白是生产小麦淀粉时副产品,具有价格低廉、产量大等特点。小麦面筋蛋白因分子量大、结构复杂、溶解性低而使其应用受限,因此在认识小麦面筋蛋白结构基础上,研究其结构及性能方面改性方法,对拓宽小麦面筋蛋白应用和缓解小麦过饱和问题都大有裨益。     

Continuous hydrolysis of modified wheat gluten in an enzymatic membrane reactor

BACKGROUND: The low solubility of wheat gluten is one of the major limitations to its use in food processing, and enzymatic hydrolysis has been found to be an effective way to prepare more soluble bioactive peptides from gluten. The aim of this study was to prepare bioactive peptides from modified wheat gluten (MWG) in a continuous enzymatic membrane reactor (EMR) that allowed rapid separation of low‐molecular‐weight peptides from hydrolysates, thus avoiding the disadvantages of batch reaction such as inefficient use of enzymes, inconsistent products due to batch‐to‐batch variation, substrate–product inhibition, low productivity and excessive hydrolysis. RESULTS: Wheat gluten was modified to decrease its lipid and starch contents in order to prevent membrane fouling. The optimal working conditions for Alcalase to hydrolyse MWG in the EMR were a substrate concentration of 20 g L^?1, an enzyme/substrate ratio of 0.03, an operating pressure of 0.04 MPa, a temperature of 40 °C and a pH of 9. The operating stability of the EMR (including residual enzyme activity, productivity and capacity) was high. The permeate fractions showed antioxidant activities that were mostly due to low‐molecular‐weight peptides. A simple theoretical kinetic model was successfully applied to the enzymatic hydrolysis of MWG in the EMR. CONCLUSION: Modification of wheat gluten made the continuous enzymatic membrane reaction more efficient and the EMR proved to be an effective means of producing peptides with particular properties and bioactivities. The permeate fractions (mainly < 1000 Da) were homogeneous and stable and also showed strong antioxidant activities. Copyright © 2011 Society of Chemical Industry     

Characterization of the Bread Made with Durum Wheat Semolina Rendered Gluten Free by Sourdough Biotechnology in Comparison with Commercial Gluten‐Free Products

Durum wheat semolina was fermented with sourdough lactic acid bacteria and fungal proteases aiming at a complete gluten hydrolysis. The gluten‐free (GF) semolina, added with naturally GF ingredients and structuring agents, was used to produce bread (rendered GF bread; rGFB) at industrial level. An integrated approach including the characterization of the main chemical, nutritional, structural, and sensory features was used to compare rGFB to a gluten‐containing bread and to 5 commercial naturally GF breads. High‐performance liquid chromatography was used for free amino acids (FAAs), organic acids, and ethanol analysis. A methanolic extract was used for determining total phenols and antioxidant activity. The bread characterization also included the analysis of dietary fibers, mycotoxins, vitamins, and heavy metals. Beyond chemical analysis, nutritional profile was evaluated considering the in vitro protein digestibility and the predicted glycemic index, while the instrumental texture profile analysis was performed to investigate the structure and the physical/mechanical properties of the baked goods. Beyond the huge potential of market expansion, the main advantages of durum wheat semolina rendered GF can be resumed in the high availability of FAAs, the high protein digestibility, the low starch hydrolysis index, and the better technological properties of bread compared to the commercial GF products currently present on the market. Vitamins, minerals, and dietary fiber profiles are comparable to those of gluten‐containing wheat bread. Also the sensory profile, determined by a panel test, can be considered the most similar to those of conventional baked goods, showing all the sourdough bread classic attributes.