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Einkorn Wheat and Intestinal Microbiota

by luciano

The state and health of the intestinal microbiota is at the center of many studies aimed at studying the role of the microbiota in diseases and how to intervene for preventive or curative purposes.
The set of microorganisms that populate our digestive system (microbiota) includes good bacterial strains but harmful ones can sometimes also be present. Indigenous strains (those that characterize our microbiota) hinder the colonization of the intestine by new microbes, including pathogenic ones. Vitamin K, for example, is synthesized by good bacteria present. Indigenous bacteria digest and ferment the favonoids contained in fruits and vegetables, promoting the production of substances that have protective effects on cardiovascular health. An essential function that our bacteria perform is to produce short-chain fatty acids, especially butyric acid. These acids protect the intestine from inflammation and the onset of tumors.
La ricerca “In Vivo Effects of Einkorn Wheat (Triticum monococcum) Bread on the Intestinal Microbiota, Metabolome, and on the Glycemic and Insulinemic Response in the Pig Model” ha questo tema come focus.
Highlighted:
Abstract: “Einkorn wheat (Triticum monococcum) is characterized by high content of proteins, bioactive compounds, such as polyunsaturated fatty acids, fructans, tocols, carotenoids, alkylresorcinols, and phytosterols, and lower α-, β -amylase and lipoxygenase activities compared to polyploid wheat. These features make einkorn flour a good candidate to provide healthier foods. In the present study, we investigated the effects of einkorn bread (EB) on the intestinal physiology and metabolism of the pig model by characterizing the glycemic and insulinemic response, and the microbiota and metabolome profiles. Sixteen commercial hybrid pigs were enrolled in the study; four pigs were used to characterize postprandial glycemic and insulinemic responses and twelve pigs underwent a 30-day dietary intervention to assess microbiota and metabolome changes after EB or standard wheat bread (WB) consumption. The postprandial insulin rise after an EB meal was characterized by a lower absolute level, and, as also observed for glucose, by a biphasic shape in contrast to that in response to a WB meal. The consumption of EB led to enrichment in short-chain fatty acid producers (e.g., Blautia, Faecalibacterium, and Oscillospira) in the gut microbiota and to higher metabolic diversity with lower content of succinate, probably related to improved absorption and therefore promoting intestinal gluconeogenesis. The observed changes, at both a compositional and metabolic scale, strongly suggest that EB consumption may support a health-promoting configuration of the intestinal ecosystem.”

omissis……

“Einkorn wheat (Triticum monococcum) was one of the first crops domesticated approximately 12,000 years ago in the Near East, alongside emmer wheat (Triticum dicoccum). Typically, einkorn was cultivated on marginal agricultural land, being able to survive in harsh environments and poor soils where other types of wheat could not survive. Spelt wheat (Triticum spelta) represents a hexaploid series of the Triticum genome constitution, which is characterized by great adaptation to a wider range of environments [1]. When compared to polyploid wheats, it has a higher content of proteins and some well recognised bioactive compounds, such as polyunsaturated fatty acids, fructans, tocols, carotenoids, alkylresorcinols, phytosterols, and lower α-, β -amylase and lipoxygenase activities [2]. These compositional traits make einkorn flour a good candidate to provide healthier foods. Specifically, the presence of antioxidant compounds and the protein profile are expected to be related to reduced cardiovascular disease and hypoallergenic effects, respectively. In particular, einkorn was shown to express few T-cell stimulatory gluten peptides, with important implications for celiac disease [3]. In vitro digested einkorn breads evidenced their higher carotenoid level as compared to modern wheats and showed a greater anti-inflammatory effect than the control (wheat bread) in Caco-2 intestinal epithelial cells [4]. Given the crucial role of the gut microbiota in the metabolism of dietary compounds, including the bio-activation of plant polyphenols into health-promoting metabolites and the production of short-chain fatty acids (SCFAs, mainly acetate, propionate, and butyrate) from fiber fermentation, as major orchestrators of the host physiology [5].”

omissis….

“Specifically, for einkorn, one of the most representative ancient grains, in vitro results evidenced a good healthy potential because of its effects on blood concentrations of glucose and insulin with a view to using einkorn-based foods in metabolic diseases [7,8], but none has considered changes in the microbiota structure as well as in the intestinal repertoire of metabolites, potentially influencing multiple metabolic and immunological pathways that are relevant to host health. In an attempt to bridge this gap, here we explored the gut microbiota and metabolome of pigs fed with an einkorn versus wheat-based bread. “

omissis……

Conclusions. “In summary, through the pig model we demonstrated a beneficial impact of EB on several aspects of the host physiology, including insulin release, fecal consistency, and microbiota and metabolome profiles, both in feces and intestinal contents. According to our findings, the consumption of EB could reduce the AUC of the first insulin peak, thus prolonging the sense of satiety. Moreover, it could modulate the intestinal ecosystem, at both the compositional and metabolic scale, towards a configuration specifically enriched in health-promoting bacteria and showing distinct metabolic signatures potentially contributing to maintaining the host homeostasis. The use of the pig model allowed, unlike in clinical human trials, the sampling of the mucosa and the content of the small intestine, thus widening the knowledge on the complexity of the food-microbiota-host interaction along the gastrointestinal tracts. The observed positive effects could be driven by the synergistic interaction of many factors, including, inter alia, the fermentation process, the food matrix, and the flour components, which result in gut-mediated effects. The evaluation of the beneficial effects of a real food is far more complex than using purified compounds, as a direct cause-effect relationship can seldom be ascribed to a single component. It is indeed foods, and not the single components, which create the diet, and exploring their complexity can better reflect their overall role on health. Although further studies and clinical trials are needed, the results that are herein reported represent a first contribution to unravel the anti-inflammatory potential of einkorn-based foods.”

“In Vivo Effects of Einkorn Wheat (Triticum monococcum) Bread on the Intestinal Microbiota, Metabolome, and on the Glycemic and Insulinemic Response in the Pig Model”. Francesca Barone et al. Nutrients 2019, 11, 16; doi:10.3390/nu11010016

Note:
A – Pigs have significant anatomical and physiological similarities with humans, particularly with regard to the intestinal structure, with comparable transit time and analogous digestive and absorptive processes [9,10]. Furthermore, like humans, they are true omnivores, unlike other potential mammalian models, such as dogs, cats, ruminants, rabbits, and rodents, which have evolutionarily developed alternative digestive strategies. Finally, both pigs and humans are colon fermenters and have similar colonic microbiota composition. All of these features make the pig one of the most important models in the field of nutrition [11,12]. Through the pig model, in the present study we investigated the impact of a 30-day nutritional intervention with einkorn or wheat bread on the intestinal ecosystem, by means of next-generation sequencing of the 16S rRNA gene and metabolomics of fecal samples, as well as samples from ileal and colonic compartments. The effects of einkorn vs. wheat bread on animal physiology, blood parameters, postprandial glycemia, and insulin response were also evaluated.

B – The metabolome refers to the complete set of small-molecule chemicals found within a biological sample. The biological sample can be a cell, a cellular organelle, an organ, a tissue, a tissue extract, a biofluid or an entire organism. The small molecule chemicals found in a given metabolome may include both endogenous metabolites that are naturally produced by an organism (such as amino acids, organic acids, nucleic acids, fatty acids, amines, sugars, vitamins, co-factors, pigments, antibiotics, etc.) as well as exogenous chemicals (such as drugs, environmental contaminants, food additives, toxins and other xenobiotics) that are not naturally produced by an organism.
The metabolome refers to the complete set of small-molecule chemicals found within a biological sample. The biological sample can be a cell, a cellular organelle, an organ, a tissue, a tissue extract, a biofluid or an entire organism. The small molecule chemicals found in a given metabolome may include both endogenous metabolites that are naturally produced by an organism (such as amino acids, organic acids, nucleic acids, fatty acids, amines, sugars, vitamins, co-factors, pigments, antibiotics, etc.) as well as exogenous chemicals (such as drugs, environmental contaminants, food additives, toxins and other xenobiotics) that are not naturally produced by an organism.

Gluten and intestinal inflammation

by luciano

gluten induces intestinal inflammation not only in celiac individuals but also in healthy ones

Intestinal inflammation is a condition of the gastro-intestinal system that affects a very large and constantly increasing number of people (1). This condition represents for the individual not only a state of disconfort that affects the quality of life but can – if underestimated or neglected – promote the onset or aggravation of serious illnesses.
An important role but still to be fully explored is played by gluten as it is pro-inflammatory.
The study ” The Role of Gluten in Gastrointestinal Disorders: A Review. Sabrina Cenni. Gastrointestinal Disorders: A Review. Nutrients 2023” provides a useful overview of its effectiveness in the prevention and management of these disorderes.

“Abstract: Gluten is only partially digested by intestinal enzymes and can generate peptides that can
alter intestinal permeability, facilitating bacterial translocation, thus affecting the immune system. Few studies addressed the role of diet with gluten in the development of intestinal inflammation and in other gastrointestinal disorders. The aim of this narrative review was to analyse the role of gluten in several gastrointestinal diseases so as to give a useful overview of its effectiveness in the prevention and management of these disorders.”

“Introduction. Gluten is a protein mass made of a complex network of gliadins and glutenins, which are proteins rich in glutamines and prolines found in most grains, such as barley, wheat, and rye [1 ,2]. Due to its high-water binding capacity and its consequent malleability and elasticity, gluten induces the formation of viscoelastic membranes, thus determining the proper consistency of dough, which allows it to be processed in bread and other foods [ 3– 5]. The high content of glutamines and prolines in gliadins make them difficult to cleave, making them able to escape degradation from gastric, pancreatic, and intestinal proteolytic enzymes [3, 4]. Therefore, gluten is what remains after the removal of starch, water-soluble proteins, and albumins [1]. In Western countries, the gluten dietary intake is approximately 5 to 20 g per day [3 , 4]. In the last decades, the literature reports an increased number of reactions following a widespread exposure to gluten [ 6]. Gluten-related diseases affect up to 10% of the general population and can be classified as three different disorders: IgE-mediated wheat allergy, Celiac disease (CD), and non-celiac gluten sensitivity (NCGS) [2, 6]. However, there is increasing evidence that gluten can trigger an innate and adaptative immune response responsible for intestinal inflammation [7]. Notably, along with other dietary elements, gluten may contribute to the development of inflammatory intestinal disorders, such as inflammatory bowel disease (IBD), as well as functional gastrointestinal disorders (FGIDs) and concur in symptom exacerbation, although its exact role is still under investigation.”

Gluten and intestinal inflammation. “Inflammation is the natural response of the innate immune system to external stimuli, such as microbial pathogens and injuries [8 ]. When the trigger persists and the immune cells are constantly activated, the inflammatory response may become chronic and self-sustainable [8]. The aetiology of inflammation is clear and easily detectable in some health conditions, while in others it can be difficult to identify [ 8]. The pathogenesis of inflammation is multifactorial. Nevertheless, genetic vulnerability, psychological stress, environmental factors, and some dietary patterns have been described as potentially implicated in the development of inflammatory phenotypes [ 8]. There are at least 50 different types of gliadin epitopes that can have an immunomodulatory and cytotoxic role or that can impact the gut permeating activities [ 8 ]; in fact, some of these can stimulate a pro-inflammatory innate immune response and others can activate specific T cells [8]. Gliadins immune cells’ activation is not only observed in celiac patients, as described by Lammers et al. [9, 10]. Indeed, their study concluded that gliadin induced an inflammatory response and, in particular, an important production of pro-inflammatory cytokines (IL-6, IL- 13, and interferon-gamma) both in Celiac patients and in healthy controls, even if proinflammatory cytokine levels were higher in Celiac patients [9, 10]. Similarly, Harris et al. showed that incubated peripheral blood mononuclear cells (PMBC) obtained from healthy HLA-DQ2 positive individuals produced proinflammatory cytokines, such as IL-23, IL-1beta, and TNF-α, when exposed to gliadin peptides [ 8, 11]. These cytokines’ production was significantly higher in Celiac patients compared to healthy controls [8,11]. Accordingly, Cinova et al., in their case-control study, demonstrated that gliadin could stimulate a substantial TNF-α and IL-8 production by monocytes, principally in celiac patients, but also, to a lesser extent, in healthy control individuals [12]. Gliadin also has an important role in modifying intestinal permeability through the reorganization of actin filaments and the modified expression of junctional complex proteins [ 8,13 ]. As demonstrated by Drago et al. and Lammers et al., gliadin’s binding to the chemokine receptor CXCR3 determines a release of zonulin, an active protein, which compromises the integrity of the intestinal barrier through the rearrangements of actin filaments, ultimately leading to an altered intestinal permeability both in Celiac and non-Celiac patients [ 9, 10, 14 ]. In conclusion, Ziegler et al. and Junker et al. reported that amylase trypsin inhibitors, found in gluten-containing cereals, have the capacity to activate toll-like receptors, thus stimulating the release of inflammatory cytokines and inducing a T-cell immune response in both celiac and non-celiac patients [15,16]”.

Einkorn wheat is the exception in relation to gluten-induced intestinal inflammation

A – Einkorn bread evidenced an anti-inflammatory effect. Integrated Evaluation of the Potential Health Benefits of Einkorn-Based Breads A. Gobetti et al. 2017.

B – Protective effects of ID331 Triticum monococcum. Protective effects of ID331 Triticum monococcum gliadin on in vitro models of the intestinal epithelium. Giuseppe Iacomino et al. (PMID: 27374565 DOI: 10.1016/j.foodchem.2016.06.014 ).

Keywords: gluten; inflammatory bowel disease; functional gastrointestinal disorders; celiac disease

Note

1 – Worldwide Prevalence and Burden of Functional Gastrointestinal Disorders, Results of Rome Foundation Global Study

BACKGROUND & AIMS: Although functional gastrointestinal disorders (FGIDs), now called disorders of gut-brain interaction, have major economic effects on health care systems and adversely affect quality of life, little is known about their global prevalence and distribution. We investigated the prevalence of and factors associated with 22 FGIDs, in 33 countries on 6 continents. METHODS: Data were collected via the Internet in 24 countries, personal interviews in 7 countries, and both in 2 countries, using the Rome IV diagnostic questionnaire, Rome III irritable bowel syndrome questions, and 80 items to identify variables associated with FGIDs. Data collection methods differed for Internet and household groups, so data analyses were conducted and reported separately. RESULTS: Among the 73,076 adult respondents (49.5% women), diagnostic criteria were met for at least 1 FGID by 40.3% persons who completed the Internet surveys (95% confidence interval [CI], 39.9–40.7) and 20.7% of persons who completed the household surveys (95% CI, 20.2–21.3). FGIDs were more prevalent among women than men, based on responses to the Internet survey (odds ratio, 1.7; 95% CI, 1.6–1.7) and household survey (odds ratio, 1.3; 95% CI, 1.3–1.4). FGIDs were associated with lower quality of life and more frequent doctor visits. Proportions of subjects with irritable bowel syndrome were lower when the Rome IV criteria were used, compared with the Rome III criteria, in the Internet survey (4.1% vs 10.1%) and household survey (1.5% vs 3.5%). CONCLUSIONS: In a large-scale multinational study, we found that more than 40% of persons worldwide have FGIDs, which affect quality of life and health care use. Although the absolute prevalence was higher among Internet respondents, similar trends and relative distributions were found in people who completed Internet vs personal interviews. Worldwide Prevalence and Burden of Functional Gastrointestinal Disorders, Results of Rome Foundation Global Study. Ami D. Sperber et al. Gastroenterology 2021;160:99–114

 

Gluten from some wheat varieties: a comparative study

by luciano

Knowledge of the gluten composition of soft, durum and spelt wheat is relevant for the success of final baked products (especially salty baked product) and/or for the production of pasta. The characteristics of gluten are also fundamental if the aim is to create products suitable for people genetically predisposed to celiac disease, for those who are sensitive to gluten without celiac disease and, extensively, for those who suffer from intestinal inflammation. For all these people it is important to make products that are as digestible and tolerable as possible. Of all the known grains, einkorn wheat is the one that is considered the most suitable for this purpose.
The study “Comparative Study on Gluten Protein Composition of Ancient (Einkorn, Emmer and Spelt) and Modern Wheat Species (Durum and Common Wheat). Sabrina Geisslitz et al. Published: 12 September 2019 in Foods (MDPI)” analyzes some characteristics of the gluten of some grains (300) highlighting the differences; it also analyzes the effect on them of the use of nitrogenous fertilizers in cultivation.

The reason for the interest in the search for varieties of einkorn, emmer and spelt:
The “ancient” wheats einkorn (Triticum monococcum L., diploid), emmer (T. dicoccum L., tetraploid) and spelt (T. aestivum ssp. spelta, hexaploid) have been cultivated in very low amounts compared to the “modern” wheat species common wheat (T. aestivum L., hexaploid) and durum wheat (T. durum L., tetraploid) in the 20th century. The reasons for the low cultivation of ancient wheats are 30–60% lower grain yields, the presence of husks and poor baking properties compared to common wheat [1]. Nevertheless, ancient wheats have been rediscovered in the last 20 years, because a growing number of consumers associate their consumption with sensory and health benefits due to their comparatively higher contents of e.g., ferulic acid, vitamins, alkylresorcinols and lutein [2–8].
Common wheat is most suitable for bread making, because the flour forms a viscoelastic dough with a high gas holding capacity when it is mixed with water. In contrast, flours of ancient wheats yield softer dough with low elasticity and high extensibility because of their poor gluten quality [1,9–11].
This latter feature translates into a less “strong”[A] and therefore more digestible gluten. In addition, einkorn and emmer do not contain the gluten fraction (33mer” : Quantitation of the immunodominant 33-mer peptide from α-gliadin in wheat flours by liquid chromatography tandem mass spectrometry. Kathrin Schalk et al. 2017. Scientific Reports.) which is considered the one that most activates the immune response in celiac subjects as well as being among the least digestible. This last feature makes these grains, especially einkorn[B], the main candidates for decreasing exposure to celiac disease in genetically predisposed subjects.

Featured in the study:
The total protein content was equally influenced by location and wheat species, however, gliadin, glutenin and gluten contents were influenced more strongly by wheat species than location. Einkorn, emmer and spelt had higher protein and gluten contents than common wheat at all four locations. However, common wheat had higher glutenin contents than einkorn, emmer and spelt resulting in increasing ratios of gliadins to glutenins from common wheat (< 3.8) to spelt, emmer and einkorn (up to 12.1). With the knowledge that glutenin contents are suitable predictors for high baking volume, cultivars of einkorn, emmer and spelt with good predicted baking performance were identified. Finally, spelt, emmer and einkorn were found to have a higher nitrogen partial factor productivity than common and durum wheat making them promising crops for a more sustainable agriculture.

….omissis.
It is generally accepted that gluten proteins are one of the most important factors determining the baking quality of wheat flours. Gluten proteins are storage proteins and classified into gliadins (GLIA) soluble in aqueous alcohol and glutenins (GLUT) soluble in aqueous alcohol only after reduction of disulfide bonds. Not only the amount, but the ratio between GLIA and GLUT (GLIA/GLUT) has been shown to be responsible for good baking quality. GLIA/GLUT of common wheat is typically 1.5–3.1 [12,13], but a recent study showed that the GLIA/GLUT of ancient wheats was much higher (spelt: 2.8–4.0; emmer: 3.6–6.7; einkorn: 4.2–12.0)
Quantitation of GLIA, GLUT, Gluten and Total Protein Contents

Integrated Evaluation of the Potential Health Benefits of Einkorn-Based Breads: anti-inflammatory effect

by luciano

Einkorn-Based Breads: anti-inflammatory effect. (Fabiana Antognoni et al. Nutrients 11-11-2017)

Abstract: Nowadays the high nutritional value of whole grains is recognized, and there is an increasing interest in the ancient varieties for producing wholegrain food products with enhanced nutritional characteristics. Among ancient crops, einkorn could represent a valid alternative. In this work, einkorn flours were analyzed for their content in carotenoids and in free and bound phenolic acids, and compared to wheat flours. The most promising flours were used to produce conventional and sourdough fermented breads. Breads were in vitro digested, and characterized before and after digestion. The four breads having the best characteristics were selected, and the product of their digestion was used to evaluate their anti-inflammatory effect using Caco-2 cells. Our results confirm the higher carotenoid levels in einkorn than in modern wheats, and the effectiveness of sourdough fermentation in maintaining these levels, despite the longer exposure to atmospheric oxygen. Moreover, in cultured cells einkorn bread evidenced an anti-inflammatory effect, although masked by the effect of digestive fluid. This study represents the first integrated evaluation of the potential health benefit of einkorn-based bakery products compared to wheat-based ones, and contributes to our knowledge of ancient grains.

Several studies have shown a clear correlation between the consumption of wholegrain and a reduced risk of cardiovascular diseases [1,2], diabetes [3], and some types of cancer [4]. The beneficial properties of wholegrain are mainly ascribed to their micronutrient and phytochemical content [5–7]. Cereals are among the richest food in phenolic acids, their content being comparable with or even higher than that found in berries, fruits, and vegetables [8]. In addition, some cereals are rich in lutein and zeaxanthin [9,10]. Micronutrients and phytochemicals are chiefly concentrated in the outer layers of grains [11], and this could explain the preventive effects associated with high wholegrain consumption [12]. Nowadays, the higher nutritional value of wholegrain compared to refined ones is recognized [13], and there is an increasing interest in ancient crops as source of wholegrain flours [14].

Einkorn (Triticum monococcum L. ssp. monococcum) is an ancient crop. Compared to polyploid wheats it has a higher content of proteins, polyunsaturated fatty acids, fructans, and phytochemicals as tocols, carotenoids, alkylresorcinols, phytosterols, and a lower α-, β-amylase and lipoxygenase activities [15]. In addition, einkorn expresses very few T-cell stimulatory gluten peptides [16]. Einkorn could represent a valid alternative for producing functional baked products.
In bakery, processing could contribute to functionality [17,18]. Sourdough fermentation, involving the inter-relation between microbial metabolism and cereal enzymes, has been shown to greatly affect the functional features of leavened baked goods [19]. This type of fermentation may produce new nutritionally active molecules such as functional peptides and amino acid derivatives [20,21], deriving from either the bacterial hydrolytic activity [20] or from their own synthetic pathways [22]. To exert a positive action in the human body, bioactive compounds must be hydrolyzed from the food matrix, and be absorbed in the intestine. The bioaccessibility of bioactive compounds, i.e., the percentage released from the food matrix and made available for uptake by the intestinal mucosa, is an important parameter that can be influenced by many different factors including the food matrix and the food processing [23,24]. Fermentation by lactic acid bacteria may improve nutrient bioaccessibility and produce compounds with anti-oxidant and anti-inflammatory activity [19]. Sourdough lactic acid bacteria have been reported to release or synthesize antioxidant and anti-inflammatory peptides during fermentation of cereal flours [20].
In this work, different wheat and einkorn flours were analyzed for their content in carotenoids and phenolic acids. The richest in these functional compounds were selected, and used to bake breads with two different fermentation procedures (conventional and sourdough).
Breads were digested in vitro using a dynamic gastro-intestinal digestor, and characterized before and after digestion. Based on integrated results, four breads were selected, and the product of their intestinal digestion was supplemented to Caco-2 intestinal cells. Cells were exposed to inflammatory stress, and the effect of supplementation on different inflammation markers was assessed.
Overall, this study has evaluated how the type of flour and the type of fermentation can influence the nutritional features of bread, and the bioaccessibility and anti-inflammatory effects of its functional compounds. The combination of different results provides an integrated vision supporting the possible health benefits of einkorn-based bread.

References

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9. Abdel-Aal, E.S.M.; Young, J.C.; Wood, P.J.; Rabalski, I.; Hucl, P.; Fregeau-Reid, J. Einkorn: A potential candidate for developing high lutein wheat. Cereal Chem. 2002, 79, 455–457. [CrossRef]

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12. Poutanen, K.; Shepherd, R.; Shewry, P.R.; Delcour, J.A.; Bjorck, I.; Van Der Kamp, J.W. Beyond whole grain:

The European HEALTH GRAIN project aims at healthier cereal foods. Cereal Foods World 2008, 53, 32–35. [CrossRef]

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A review on KAMUT khorasan wheat. Int. J. Food Sci. Nutr. 2016, 28, 1–9. [CrossRef] [PubMed]

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17. Sánchez-Pardo, M.E.; Blancas-Nápoles, J.A.; Vázquez-Landaverde, P.A.; Nari, A.; Taglieri, I.; Ortiz-Moreno, A.; Mayorga-Reyes, L.; Sanmartin, C.; Bermúdez-Humarán, L.G.; Torres-Maravilla, E. The use of Mexican xaxtle as leavening agent in Italian straight dough bread making to produce pulque bread. Agrochimica 2016, 60, 329–342.

18. Venturi, F.; Sanmartin, C.; Taglieri, I.; Nari, A.; Andrich, G.; Zinnai, A. Effect of the baking process on artisanal sourdough bread-making: A technological and sensory evaluation. Agrochimica 2016, 60, 222–234.

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Natural Variation in Toxicity of Wheat

by luciano

Natural Variation in Toxicity of Wheat: Potential for Selection of Nontoxic Varieties for Celiac Disease Patients (and useful for disease prevention in individuals at risk)
Liesbeth Dekking, Harry Jonker et al. Article in Gastroenterology · October 2005. DOI: 10.1053/j.gastro.2005.06.017 · Source: PubMed

“Background & Aims: Celiac disease (CD) is an intestinal disorder caused by T-cell responses to peptides derived from the gluten proteins present in wheat. Such peptides have been found both in the gliadin and glutenin proteins in gluten. The only cure for CD is a lifelong gluten-free diet. It is unknown, however, if all wheat varieties are equally harmful for patients. We investigated whether wheat varieties exist with a nat- ural low number of T-cell–stimulatory epitopes. Methods: Gluten proteins present in public databases were analyzed for the presence of T-cell–stimulatory sequences. In addition, wheat accessions from diploid (AA, SS/BB, and DD genomes), tetraploid (AABB), and hexaploid (AABBDD) Triticum species were tested for the presence of T-cell–stimulatory epitopes in gliadins and glutenins by both T-cell and monoclonal anti-body–based assays. Results: The database analysis readily identified gluten proteins that lack 1 or more of the known T-cell–stimulatory sequences. Moreover, both the T-cell– and antibody-based assays showed that a large variation exists in the amount of T-cell– stimulatory peptides present in the wheat accessions. Conclusions: Sufficient genetic variation is present to endeavor the selection of wheat accessions that con- tain low amounts of T-cell–stimulatory sequences. Such materials may be used to select and breed wheat varieties suitable for consumption by CD patients, contributing to a well-balanced diet and an increase in their quality of life. Such varieties also may be useful for disease prevention in individuals at risk.”

The study also recalls the influence of gluten intake on early childhood nutrition:

“It is known that early exposure to gluten and a double HLA-DQ2 gene dose both promote CD development. In Sweden the addition of gluten to infant food led to a 5-fold increase in the occurrence of CD in the 1980s,and HLA-DQ2 homozygous individuals have a 5-fold increased risk for developing CD com pared with HLA-DQ2 heterozygous individuals. A large repertoire of abundant immunogenic gluten peptides in the diet, together with a high copy number of HLA-DQ2, thus favors the breaking of oral tolerance. In present-day practice, gluten is introduced into the diet of infants at 6–7 months of age. Because there is no restriction in the amount of gluten given, gluten intake at age 12 months is between 6 and 9 g/day, whereas gluten-specific T cells of CD patients are known to respond to microgram amounts. The sudden introduction of grams of gluten thus may play an important role in the breaking of oral tolerance. As we have suggested previously, the current understand- ing of the development of the disease may call for a more gradual and/or reduced intake of gluten in infants. The breeding of wheat varieties with a lower amount of T-cell–stimulatory gluten peptides potentially could aid in reaching that goal.”

….omissis “Wheat gluten is a group of proteins that can be partitioned into 2 protein families: the glutenins and the gliadins. The glutenins can be subdivided further into high molecular weight (HMW) and low molecular weight (LMW) glutenins and the gliadins can be divided into α, γ and ω gliadins. At present, many gluten- derived T-cell–stimulatory peptides are known and they originate from the α, and γ-gliadins, and the HMW and LMW glutenins. Homologue sequences are found in the secalins of rye, the hordeins of barley, and the avenins of oats. Gluten and gluten-like molecules thus contain many immunogenic peptides. Moreover, the unique food-industrial properties of gluten are in part related to a very high proline content that renders gluten relatively resistant to enzymatic degradation in the gastrointestinal tract. Hence, many of the immunogenic gluten peptides are likely to survive for extended periods in the intestine, increasing the probability of triggering a T-cell response. Thus, the unique properties of gluten are linked tightly to their disease- inducing potential in CD patients”.

Deepening
Celiac disease is a prevalent disorder characterized by a chronic intestinal inflammation driven by HLA-DQ2 or -DQ8-restricted T cells specific for ingested wheat gluten peptides. The dominant T-cell responses are to epitopes that cluster within a stable 33mer fragment formed by physiologic digestion of distinct alpha-gliadins. Celiac disease is treated by excluding all gluten proteins from the diet. Conceivably, a diet based on baking-quality gluten from a wheat species that expresses no or few T-cell stimulatory gluten peptides should be equally well tolerated by the celiac patients and, importantly, also be beneficial for disease prevention. To identify baking quality, harmless wheat, we followed the evolution of the wheat back to the species that most likely have contributed the AA, BB, and DD genomes to the bread wheat. Gluten were extracted from a large collection of these ancient wheat species and screened for T-cell stimulatory gluten peptides. Distinct differences in the intestinal T-cell responses to the diploid species were identified. Interestingly, we found that the fragments identical or equivalent to the immunodominant 33mer fragment are encoded by alpha-gliadin genes on the wheat chromosome 6D and thus absent from gluten of diploid einkorn (AA) and even certain cultivars of the tetraploid (AABB) pasta wheat. These findings have implications for celiac disease because they raise the prospect of identifying or producing by breeding wheat species with low or absent levels of harmful gluten proteins.
Mapping of Gluten T-Cell Epitopes in the Bread Wheat Ancestors: Implications for Celiac Disease. Tore Jensen et al. March 2005 Gastroenterology 128(2):393-401; DOI:10.1053/j.gastro.2004.11.003