Changes in the starch-protein interface depending on common wheat grain hardness revealed using atomic force microscopy

The Atomic Force Microscope tip was used to progressively abrade the surface of non-cutted starch granules embedded in the endosperm protein matrix in grain sections from wheat near-isogenic lines differing in the puroindoline b gene and thus hardness. In the hard near-isogenic wheat lines, starch granules exhibited two distinct profiles corresponding either to abrasion in the surrounding protein layer or the starch granule. An additional profile, only identified in soft lines, revealed a marked stop in the abrasion at the protein-starch transition similar to a lipid interface playing a lubricant role. It was related to the presence of both wild-type puroindolines, already suggested to act at the starch-protein interface through their association with polar lipids.This study revealed, for the first time, in situ differences in the nano-mechanical properties at the starch-protein interface in the endosperm of wheat grains depending on the puroindoline allelic status

A compositional breakage equation for wheat milling

The compositional breakage equation is derived, in which the distributions of botanical components following milling of wheat are defined in terms of compositional breakage functions and concentration functions. The forms of the underlying functions are determined using experimental data for Outer Pericarp, Intermediate Layer, Aleurone and Starchy Endosperm generated from spectroscopic analysis of milled fractions of a hard and a soft wheat milled under Sharp-to-Sharp (S-S) and Dull-to-Dull (D-D) dispositions. For the hard Mallacca wheat, the Outer Pericarp, Intermediate Layer and Aleurone compositions mostly varied with particle size in similar ways, consistent with these layers fusing together as “bran” and breaking together, although with possibly a subtle difference around the production of very fine particles under D-D milling. By contrast, for the soft Consort wheat, Outer Pericarp, Intermediate Layer and Aleurone were distributed in broken particles very differently, particularly under D-D milling, suggesting a different breakage mechanism associated with differences in the mechanical properties and adhesion of the bran layers. These new insights into the nature of wheat breakage and the contributions of the component tissues could have implications for wheat breeding and flour mill operation

Do ancient wheats contain less gluten than modern bread wheat, in favour of better health?

Popular media messaging has led to increased public perception that gluten-containing foods are bad for health. In parallel, ‘ancient grains’ have been promoted with claims that they contain less gluten. There appears to be no clear definition of ‘ancient grains’ but the term usually includes einkorn, emmer, spelt and Khorasan wheat. Gluten is present in all wheat grains and all can induce coeliac disease (CD) in genetically susceptible individuals. Analyses of ‘ancient’ and ‘modern’ wheats show that the protein content of modern bread wheat (Triticum aestivum) has decreased over time while the starch content increased. In addition, it was shown that, compared to bread wheat, ancient wheats contain more protein and gluten and greater contents of many CD-active epitopes. Consequently, no single wheat type can be recommended as better for reducing the risks of or mitigating the severity of CD. An estimated 10% of the population of Western countries suffers from gastrointestinal symptoms that lack a clear organic cause and is often referred to as irritable bowel syndrome (IBS). Many of these patients consider themselves gluten sensitive, but in most cases this is not confirmed when tested in a medical setting. Instead, it may be caused by gas formation due to fermentation of fructans present in wheat or, in some patients, effects of non-gluten proteins. A significant overlap of symptoms with those of CD, IBS and inflammatory bowel disease makes a medical diagnosis a priority. This critical narrative review examines the suggestion that ‘ancient’ wheat types are preferred for health and better tolerance

Do ancient wheats contain less gluten than modern bread wheat, in favour of better health?

Popular media messaging has led to increased public perception that gluten‐containing foods are bad for health. In parallel, ‘ancient grains’ have been promoted with claims that they contain less gluten. There appears to be no clear definition of ‘ancient grains’ but the term usually includes einkorn, emmer, spelt and Khorasan wheat. Gluten is present in all wheat grains and all can induce coeliac disease (CD) in genetically susceptible individuals. Analyses of ‘ancient’ and ‘modern’ wheats show that the protein content of modern bread wheat (Triticum aestivum) has decreased over time while the starch content increased. In addition, it was shown that, compared to bread wheat, ancient wheats contain more protein and gluten and greater contents of many CD‐active epitopes. Consequently, no single wheat type can be recommended as better for reducing the risks of or mitigating the severity of CD. An estimated 10% of the population of Western countries suffers from gastrointestinal symptoms that lack a clear organic cause and is often referred to as irritable bowel syndrome (IBS). Many of these patients consider themselves gluten sensitive, but in most cases this is not confirmed when tested in a medical setting. Instead, it may be caused by gas formation due to fermentation of fructans present in wheat or, in some patients, effects of non‐gluten proteins. A significant overlap of symptoms with those of CD, IBS and inflammatory bowel disease makes a medical diagnosis a priority. This critical narrative review examines the suggestion that ‘ancient’ wheat types are preferred for health and better tolerance

What’s new on wheat grain milling behavior knowledge in joint Research Unit IATE Montpelllier-France

What’s new on wheat grain milling behavior knowledge in joint Research Unit IATE Montpelllier-France . Invitatio

Both genetic and environmental conditions affect wheat grain texture: Consequences for grain fractionation and flour properties

International audienceThis review summarizes the results of studies on near-isogenic common wheat lines differing in the Pinb-D1 allele encoding puroindoline B or durum wheat into which both wild-type puroindoline genes were introduced. The material was grown in different environments to evaluate the respective effect of puroindoline genes or of the environmental factors on grain characteristics and milling behavior. Environmental conditions were found to impact grain porosity (=1/vitreousness) and the presence of both wild-type puroindoline genes was found to reduce the vitreousness threshold under 60%. Hardness measurements with single kernel characterization system were found to differ from near-infrared reflectance spectroscopy analysis and were linearly related to vitreousness but differently depending on the puroindoline allele carried. Puroindoline genes were found to play a major role in the grain porosity, breaking energy, size of generated particles and in the concentration of phytic acid and damaged starch into flour whereas vitreousness introduced variations in the ability to break and in the level of damaged starch. Finally, the highest flour yield is obtained from either vitreous common wheat grains carrying the wild-type puroindoline alleles or carrying mutated alleles and displaying low vitreousness. This result was confirmed using common French wheat cultivars whose puroindoline genes were identified

Le grain de blé tendre: le point des recherches sur sa transformation en farine

Le grain de blé tendre: le point des recherches sur sa transformation en farine. Congrès annuel de l’Association des Professeurs de Boulangeri

Improving wheat quality for processing and health

Improving wheat quality for processing and health. 1st Meeting of the Expert Working Group on Improving Wheat Quality for Processing and Healt

Neutral ose composition of wheat grain tissues and its use to assess tissue composition in mill streams

Conventional wheat grain milling processes aim at dissociating and isolating the starchyendosperm, recovered in flour or semolina, from the outer layers as bran fractions.Proportions of each tissue in mill streams impact their nutritional quality or their end-useproperties. Among various methodologies, measurement of biochemical markers specificallylocated in the different wheat grain tissues was successfully applied to evaluate these tissueproportions within fractions. However this method implies at least four differentmeasurements and, due to variability in marker amounts, could lead to some loss of accuracy.Considering the diversity in neutral ose composition between each grain tissue, this data,coming only from one biochemical analysis, could be useful to quantify the tissue proportion.The objective of this study was first to evaluate the specificity and variability of neutral osecomposition in durum and common wheat grain tissues and then to evaluate its ability topredict tissue composition in various mill streams based on this characterization. Pure starchyendosperm, aleurone layer, outer pericarp were dissected as well as a composite layer made ofnucellar epidermis+testa+inner pericarp. Starchy endosperm, with high amount of glucose(related to the presence of starch) was easily differentiated from peripheral tissues (richer inarabinose and xylose present in wheat cell wall polysaccharides). Based on measured tissueproportion obtained by another method, the ose composition in mill streams was predictedfrom pure tissue composition: the best results were obtained for arabinose and xylose contentbut with a global error of 13 %. On the other hand, multiple regression methods (PLS, MCR)were used to predict tissue proportion in mill streams based on ose composition. If outerpericarp and starchy endosperm could be predicted with a satisfactory error of 5%, predictionof the aleurone layer and intermediate layer containing testa was not straightforward witherror higher than 10%. The high similarity between these tissues could be part of theexplanation. Therefore even if variability in ose composition due to different cultivars was notfound significant, the specificity for each tissue appeared insufficient to envision suchanalyses to determine the tissue composition in mill streams

High-pressure as a tool to study some proteins properties: conformational modification, activity and oligomeric dissociation

101 ref.International audienceHydrostatic pressure, as temperature, constitutes an efficient physical parameter to modify equilibrium and rate of biological processes. In this review, we will not present all the implications of high-pressure, but we will focus on proteins’ structural conformational modification, unfolding, oligomeric or protein aggregates dissociation and enzymatic activity. To this aim, some optical methods that were used in association with high-pressure to study protein structures (i.e. fourth derivative absorbance spectroscopy, fluorescence spectroscopy, infrared spectroscopy) and protein activities (kinetics measurements: stopped-flow and pressure jump methods) will be described in details. Some applications of these methods will be given including effects on proteins of food interest