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.     

Physiopathology and Management of Gluten‐Induced Celiac Disease

Proline‐ and glutamine‐rich gluten proteins are one of the major constituents of cereal dietary proteins, which are largely resistant to complete cleavage by the human gastrointestinal (GI) digestive enzymes. Partial digestion of gluten generates approximately 35 amino acids (aa) immunomodulatory peptides which activate T‐cell–mediated immune system, followed by immunological inflammation of mucosa leading to the onset of celiac disease (CD). CD is an autoimmune disease associated with HLA–DQ2/DQ8 polymorphism and dysbiosis of gut microbiota. CD is either diagnosed using duodenal mucosal biopsis or serological testing for transglutaminase 2 (TG2) specific antibodies (IgA and IgG). Current therapy for CD management is gluten‐free diet, while other therapies like glutenase, probiotics, immunomodulation, jamming of HLA‐DQ2, inhibition of TG2, and gluten tolerance aided by gluten tolerizing vaccines are being developed.     

Gluten‐sensitive enteropathy (celiac disease)

Abstract

Gluten‐sensitive enteropathy (celiac disease—GSE) is induced by dietary wheat gliadin and related proteins in genetically susceptible individuals. Enzyme abnormalities and a lectin‐like gluten toxicity could be implicated in the pathogenesis of the disease, but most evidence suggests that the mucosal lesion of GSE represents an imraunologicaly mediated tissue injury triggered by gluten ingestion within the context of a particular assortment of major histocompatibility complex genes. The process leading to the mucosal damage is as yet still poorly understood, as well as the amino acid sequence(s) of gliadin and related proteins responsible for toxicity. Several in vitro models are available to test toxicity of gliadin amino acid sequences, pathogenesis of mucosal damage, and possible protective mechanisms, but definitive conclusions must rely on in vivo jejunal, and probably rectal, challenge studies in treated celiac patients. Animal models could contribute to the understanding of GSE pathogenesis. Symptomatic GSE affects approximately 1:1000 individuals in Europe, but this figure is likely to underestimate the real prevalence of the disease. In fact, many cases are asymptomatic, and they may be recognized only by means of large screening programs. Furthermore, it is now becoming clear that a condition of latent gluten sensitivity (preceliac disease) can exist in some apparently normal individuals, who present normal (or almost normal) jejunal histology while eating gluten. In some regions of Europe GSE is still presenting more often in the infantile age with classical gastrointestinal symptoms, but in other countries the clinical presentation is changing, coming closer to the adult type of the disease, and the age of onset of symptoms is shifting upward. Liver, joint, hematological, gynecological, and neurological symptoms are increasingly being recognized. A number of diseases have been found to be associated with GSE; among these are: IgA deficiency, IgA nephropathy, sarcoidosis, insulin‐dependent diabetes mellitus, and a range of other autoimmune diseases. The diagnosis of GSE is based on the finding of severe histological lesion of the jejunum while the patient is on a gluten‐containing diet, and on its disappearance once gluten is excluded from the diet. As far as therapy is concerned, a lifelong, strict gluten‐free diet is mandatory for GSE patients. Among other long‐term problems, an increased risk of intestinal lymphoma has been reported in those patients on a normal or even on a gluten‐poor diet.     

Inorganic and Total Arsenic Contents in Rice‐Based Foods for Children with Celiac Disease

Celiac disease is an autoimmune disease that affects the villi of the small intestine causing abdominal pain, gas, diarrhea, or bad absorption due to gluten intolerance. The only treatment for this disease consists of a lifelong gluten free diet; this is, celiac people cannot consume products containing gluten, such as wheat, barley, and rye, but they can use rice and corn. Thus, rice flour is mainly used for the manufacturing of the basic products of this population. Unfortunately, rice can contain high contents of total (t‐As) and inorganic (i‐As) arsenic. The current study demonstrated that products for celiac children with a high percentage of rice contained high concentrations of arsenic (256 and 128 μg kg^?1). The daily intake of i‐As ranged from 0.61 to 0.78 μg kg^?1 body weight (bw) in children up to 5 y of age; these values were below the maximum value established by the EFSA Panel (8.0 μg kg^?1 bw per day), but it should be considered typical of populations with a high exposure to this pollutant. Finally, legislation is needed to improve the labeling of these special rice‐based foods for celiac children; label should include information about percentage, geographical origin, and cultivar of the used rice.     

一种基于BALB/c背景由膳食麸质引起的乳糜泻小鼠模型的构建及其评价

目的：利用麸质诱导建立小鼠乳糜泻（celiac disease,CeD）模型,通过检测乳糜泻相关指标来评价该模型的可行性。方法：将连续食用无麸质饲料3 代以上的雌性BALB/c小鼠（6～8 周龄）随机分为两组（对照组（Control组）和模型组（CeD组））,CeD组于实验开始的第1天将饲料换为麸质含量2.5 g/kg的含麸质饲料,Control组则继续饲喂无麸质饲料。实验前3 周,分别给予CeD组每只小鼠腹腔注射含150 μg麦醇溶蛋白的磷酸盐缓冲溶液（0.2 mL 0.01 mol/L）,每周两次。在实验的第4周,给予CeD组每只小鼠后脚掌注射乳化有50 μg麦醇溶蛋白的弗氏完全佐剂50 μL两次（第1天和第4天各注射一次）。利用血清荧光素异硫氰酸酯-葡聚糖质量浓度表征小鼠的肠道通透性;利用实时荧光定量聚合酶链式反应检测小鼠十二指肠组织中紧密连接蛋白（ZO-1、ZO-2、Claudin-1等）、相关炎症因子白细胞介素（（interleukin,IL）-15、干扰素（interferon,IFN）γ和IL-4等）和相关免疫细胞的表面标志物基因（CD4、CD19、CD138等）的表达水平;采用酶联免疫吸附试验测定小鼠十二指肠中组织转谷氨酰胺酶（tissue transglutaminase,tTG）和连接蛋白水平。结果：相比Control组,CeD组小鼠十二指肠肠道屏障被明显破坏,小肠绒毛长度明显缩短,TGM2 mRNA相对表达量显著升高（P＜0.05）,与乳糜泻相关的炎症因子和免疫细胞的标志物基因相对表达量都显著升高。结论：该造模方法在肠道病理情况、肠道屏障以及免疫方面均能很好地模拟临床上乳糜泻的病理学特征,可用于未来乳糜泻新的潜在治疗措施研究中。     

Gluten-related disorders: Celiac disease,wheat allergy,and nonceliac gluten sensitivity

Abstract

The consumption of gluten-free products is becoming an increased alimentary habit in the general population. The scientific unfounded perception suggesting that the avoidance of gluten would improve health or that gluten could be toxic for humans are fostering medically unjustified adherences to a gluten-free diet. Currently, only patients diagnosed with celiac disease are advised to follow a strict lifelong gluten-free diet. In the same way, patients diagnosed with IgE-mediated wheat allergy must avoid exposure to wheat in any form. In that context, a third disorder, called nonceliac gluten sensitivity, characterized by distress after gluten consumption and in which neither celiac disease nor IgE-mediated allergy plays a role, has gained increased attention in the last years. Although important scientific advances have been made in the understanding of the pathologic mechanisms behind nonceliac gluten sensitivity, this disorder is still a matter of active debate in the scientific community. In the present review, the most recent advances in the immunopathology, diagnostic biomarkers and susceptibility determinants of gluten-related diseases are summarized and discussed. Furthermore, an updated overview of the new potential therapies that are currently underway for the treatment of gluten-related disorders is also provided.     

Gluten contamination of cereal foods in Canada

Persons suffering from celiac disease (CD) must avoid foods containing gluten or those contaminated with wheat, barley, or rye. This study was designed to estimate gluten contamination of cereal-based foods available in Canada, whether labelled gluten-free or not. About half of the 148 foods sampled were labelled as gluten-free. According to R5-enzyme-linked immunosorbent assay (ELISA), twenty-three cereal-based foods (or 15%) contained more than 20 mg of gluten per kg, including sixteen regular and seven gluten-free foods, the latter being the least contaminated. When used in combination with R5-ELISA, AOAC-ELISA (not detecting barley) was a simple and efficient tool to roughly estimate the nature of the gluten contamination, which was later confirmed by real-time polymerase chain reaction for barley, and wheat/barley/rice. Rice-, corn- or quinoa-based foods were the safest for celiac patients. In addition to misleading food labelling for both gluten-rich and gluten-free foods, critical issues for persons with CD included foods made with oats or buckwheat (contaminated with wheat and barley gluten) in addition to those, such as breakfast cereals, specifically enriched with barley malt ingredients.     

Celiac Disease—Background,Molecular, Bioinformatics and Analytical Aspects

This review summarizes the background of celiac disease (CD), and the available bioinformatic and analytical methods designed to evaluate the molecular aspects of celiac-toxic proteins and peptides. CD is a T-cell-mediated autoimmune disease of the small intestine that is induced by ingestion of gluten proteins from wheat, barley, rye, and, rarely, after consumption of oats. This disease is characterized by malabsorption of nutrients from the intestine. It has been demonstrated that polypeptide chains of gliadin contain repeating amino acid sequences that constitute epitopes for a respective lymphocyte receptor (TCR). It was reported that the optimal length of a polypeptide chain suitable for a TCR is 10 to 15 amino acid residues. Celiac toxic proteins and peptides were characterized by the following methods and techniques: immunochemical, electrophoretic, chromatographic, and mass spectrometric. Characterization of celiac toxic peptides may provide sufficient information to breed out these sequences from wheat, barley or rye, whilst retaining its baking properties. An improved understanding of the immune response to gluten has provided an insight into possible future advances in the treatment of celiac disease.     

A Grounded Guide to Gluten: How Modern Genotypes and Processing Impact Wheat Sensitivity

The role of wheat, and particularly of gluten protein, in our diet has recently been scrutinized. This article provides a summary of the main pathologies related to wheat in the human body, including celiac disease, wheat allergy, nonceliac wheat sensitivity, fructose malabsorption, and irritable bowel syndrome. Differences in reactivity are discussed for ancient, heritage, and modern wheats. Due to large variability among species and genotypes, it might be feasible to select wheat varieties with lower amounts and fewer types of reactive prolamins and fructans. Einkorn is promising for producing fewer immunotoxic effects in a number of celiac research studies. Additionally, the impact of wheat processing methods on wheat sensitivity is reviewed. Research indicates that germination and fermentation technologies can effectively alter certain immunoreactive components. For individuals with wheat sensitivity, less‐reactive wheat products can slow down disease development and improve quality of life. While research has not proven causation in the increase in wheat sensitivity over the last decades, modern wheat processing may have increased exposure to immunoreactive compounds. More research is necessary to understand the influence of modern wheat cultivars on epidemiological change.     

Characterization of Antibodies for Grain‐Specific Gluten Detection

Gluten ingestion causes immunoglobulin E (IgE)‐mediated allergy or celiac disease in sensitive individuals, and a strict gluten‐free diet greatly limits food choices. Immunoassays such as enzyme‐linked immunosorbent assay (ELISA) are used to quantify gluten to ensure labeling compliance of gluten‐free foods. Anti‐gluten antibodies may not exhibit equal affinity to gluten from wheat, rye, and barley. Moreover, because wheat gluten is commonly used as a calibrator in ELISA, accurate gluten quantitation from rye and barley contaminated foods may be compromised. Immunoassays utilizing grain‐specific antibodies and calibrators may help improve gluten quantitation. In this study, polyclonal antibodies raised against gluten‐containing grain‐specific peptides were characterized for their immunoreactivity to gluten from different grain sources. Strong immunoreactivity to multiple gluten polypeptides from wheat, rye, and barley was observed in the range 34 to 43 kDa with anti‐gliadin, 11 to 15 and 72 to 95 kDa with anti‐secalin, and 30 to 43 kDa with anti‐hordein peptide antibodies, respectively. Minimal or no cross‐reactivity with gluten from other grains was observed among these antibodies. The anti‐consensus peptide antibody raised against a repetitive amino acid sequence of proline and glutamine exhibited immunoreactivity to gluten from wheat, rye, barley, and oat. The antibodies exhibited similar immunoreactivity with most of the corresponding grain cultivars by ELISA. The high specificity and minimal cross‐reactivity of grain‐specific antibodies suggest their potential use in immunoassays for accurate gluten quantitation.     

How Looking for Celiac‐Safe Wheat Can Influence Its Technological Properties

Because of the continuous increase in the prevalence of gluten‐related disorders, selection of wheat with a low content of immunogenic gluten epitopes could be an innovative alternative for prevention. In this review, the focus is on literature data concerning the deallergenization tools of wheat, which are mainly related to breeding approaches (classic and advanced) and processing operations (germination and fermentation). Until now, no safe wheat genotype has been identified, whereas decreasing wheat allergenicity is possible. On the other hand, the decrease of gluten or some of its epitopes can strongly affect technological properties. Thus, obtaining celiac‐safe gluten without affecting the technological properties of wheat could be considered as a new challenge that scientists will be facing. Celiac‐safe wheat‐based product development could be a great revolution in the market of foods for special medical purposes. The present paper is aiming to: (a) review the strategies and the approaches used, or that can be used, for developing low allergenic wheat: their utilities and limits were also discussed and (b) screen the impact of gluten reduction or removal on the quality of wheat end‐use products.     

乳糜泻动物模型研究进展

乳糜泻是一种携带遗传易感基因的人群因摄入麸质蛋白而引起由T细胞介导的复杂肠道疾病。麸质蛋白是小麦、大麦、黑麦等谷物中的主要贮藏蛋白,由麦醇溶蛋白和麦谷蛋白组成,是诱发乳糜泻的主要环境因素。患者终生严格执行无麸质饮食是目前治疗乳糜泻的最佳方法。然而,在生活中,患者难以完全避免摄入麸质蛋白,且长期的无麸质饮食将影响患者的社会交往活动,加重患者的心理与经济负担。因此,有必要研究新的冶疗方法或药物以用于辅助或替代无麸质饮食疗法。为了验证新方法的有效性和安全性,构建动物模型模拟乳糜泻的病症是必须的。因此,本文着重介绍了判断乳糜泻动物模型是否成功建立应选取的检测指标、乳糜泻动物模型的致敏方式及目前已建立的动物模型特点,为进一步完善乳糜泻动物模型提供参考。     

以麸质蛋白为靶向的乳糜泻治疗方法研究进展

乳糜泻(celiac disease,CD)是携带遗传易感基因人群的自身免疫疾病,其特点是摄入含麸质蛋白的小麦或大麦和黑麦产品后,小肠会受到炎症性损伤。乳糜泻患者必须终生坚持无麸质饮食,这是目前唯一有效的治疗方法。然而,严格遵守无麸质饮食是困难的,需要新的治疗方法来补充甚至替代饮食治疗。尽管迄今为止,还没有技术允许乳糜泻患者无限制地安全食用含麸质的产品,但随着对乳糜泻发病机制认识的不断深入,在无麸质饮食替代疗法方面已经取得了有希望的进展。本文综述了以麸质蛋白为靶向的乳糜泻治疗方法研究进展,如下调麦醇溶蛋白的表达、麦醇溶蛋白的隔离、谷氨酰胺残基的转酰胺化和免疫显性肽的酶解,批判性地讨论了这些治疗方法的实用性和获得的结果。     

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.     

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.     

Next-generation therapies for celiac disease: The gluten-targeted approaches

BackgroundWheat is one of the main foods of the human diet. It contains a protein complex, gluten, which is primarily responsible for the rheological behavior of wheat flours. However, it is gluten that triggers and maintains the enteropathy in celiac disease, a common autoimmune disorder of the small intestine. Individuals who suffer from celiac disease must follow a gluten-free diet, the only effective treatment available. Compliance to the restrictive diet is demanding and new treatment strategies for celiac disease are desired by patients and clinicians.Scope and approachBased on increasing knowledge of the pathogenesis of celiac disease, some gluten-targeted approaches have been devised, such as down-regulation of gliadin expression, proteolysis of immunodominant peptides, transamidation of glutamine residues and sequestering of gliadin proteins. The present work critically discusses these experimental therapies, their usefulness, and the results obtained, in order to infer what the next generation of therapies for celiac disease will be.Key findings and conclusionsThe gluten detoxification technologies have shown promising results in clinical trials by attenuating the symptomatology associated with celiac disease. These include gluten-specific proteases, which are close to entering the market for use by patients who may have mistakenly ingested food contaminated with gluten. Although so far none of the technologies allow the safe consumption of gluten without limitations, new and promising advances have been made, thus creating positive expectations in the search for an alternative to the gluten-free diet.     

高粱食品:一种古老作物带来新的健康

高粱是一种古老的作物初次被驯化于非洲,并在公元前3000年左右推广到了世界各地.高粱是一种抗旱的谷类作物,生长在其它作物无法生存的半干旱气候条件下,在2002年世界高粱产量达到5450万公吨.美国高粱年产量可达1300～1500万公吨左右,其中30%～50%用于出口,在西方国家中用高粱喂养动物已非常普遍,大约世界高粱产量的40%被用于作为非洲和印度等国家人民的食物.在美国对于患有腹乳糜泻疾病无法适应面筋蛋白的人已经用白色食品级的杂交作物生产出运用于无小麦产品作为食用,不能食用小麦或其它谷类作物比如黑麦,大麦,他们提供了些刺激性小的面粉已成为用于制造无小麦食品的原料.当高粱缺乏面筋时,高粱粉便不能生产有黏性和弹性的生面团,因此蛋奶糊配方被用于制造高粱产品,包括面包威化饼干、面条和比萨饼皮,这些原来都是由面粉制成.研究表明,高粱系生产高质量食物,因此种植高梁将被用于改善提高食物质量,最近一些研究表明由于这种古老作物包括含有二十烷醇(policosanols)的多酚复合物和高粱蜡的高抗氧化水平,可能对健康有独特的益处,对于保护心血管的健康至关重要.尤其在把小麦作为主要食物的西方世界,对于给患有腹乳糜泻疾病的人们提供了健康稳定的主食是一个挑战.因此高粱这种古老的作物作为21世纪的主要谷类作物引来了新的兴趣和前途,这是由于(1)它对于患有腹乳糜泻疾病的人是一种富有潜力的主食.(2)保持食物的营养和健康的高抗氧化水平和蜡含量.(3)由于它的抗干旱性和有限供水量的高生产量,2030年预期人口指数增长明显.     

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.     

Is the calculation of the gluten content by multiplying the prolamin content by a factor of 2 valid?

Presently, the only essential therapy of celiac disease (CD) is the permanent strict withdrawal of gluten from the diet. With respect to gluten containing foods from wheat, rye, barley, and oats, CD patients have to consume surrogates that must be gluten-free according to the “Codex Alimentarius Standard for Gluten-Free Foods”. The recent “Draft Revised Standard” proposes a gluten threshold of 20 mg per kg gluten-free product. For gluten quantitation, the alcohol-soluble prolamins should be extracted and analyzed by an immunochemical method; the amount of gluten is calculated by multiplying the prolamin content by the factor of 2. To investigate, whether this calculation is valid in any case of contamination of gluten-free products by wheat, rye, barley, and oats, wholemeal or white flours from common wheat, spelt, durum wheat, kamut, emmer, einkorn, rye, barley and oats were analyzed for the ratio of prolamins to glutenins (PROL/GLUT) by a combination of extraction and reversed-phase HPLC procedures. Additionally, different industrial wheat starches were analyzed for their prolamin and total gluten content using different extraction and concentration steps followed by gel permeation HPLC. The results for the cereal flours revealed that the ratio PROL/GLUT was generally higher than 1.0 as proposed by the “Draft Revised Standard” and strongly influenced by cereal species and variety. Common wheat showed the lowest ratio (1.5–3.1), followed by oats and spelt (1.7–3.3), barley (1.4–5.0), durum wheat and kamut (3.1–3.4), emmer (3.5–7.6), rye (6.3–8.2), and einkorn (4.0–13.9). In any case, the gluten content of gluten-free products contaminated with CD activating cereals was generally overestimated, when the prolamin content was multiplied by the factor of 2. In extreme cases, e.g., contamination with rye, the overestimation amounted to 72–79%. Completely different PROL/GLUT ratios were found in ten commercial wheat starches ranging from 0.2 to 4.9. Obviously, the quality of wheat cultivars used for starch production and/or different process parameters, e.g., washing steps, influenced the composition of gluten proteins adherent to starch granules. For wheat starch, the calculation of the gluten content by 2 × PROL may either lead to underestimation (−71% at most) or overestimation (+66% at most). In conclusion, this calculation is invalid; therefore, a future task will be the development of immunoassays with antibodies against all types of storage proteins from wheat, rye, barley, and oats.