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

Prediction of relative tissue proportions in wheat mill streams by Fourier transform mid-infrared spectroscopy

Axe 1 Fractionnement des Agro ressources : bases structurales et physicochimiques ; procédés de broyage, extraction et de séparationInternational audienceFourier-transform mid-infrared (FTIR) spectroscopy was investigated as a method to quantify the relative wheat grain tissue proportion in milling fractions. Spectra were acquired with a FTIR spectrometer equipped with an attenuated total reflectance device on ground samples, and the relative tissue proportion was determined according to the biochemical marker methodology as the reference method. Partial least-squares models were developed independently to predict the amount of outer pericarp, aleurone layer, starchy endosperm, and an intermediate layer (made up of inner pericarp plus seed coat plus nucellar epidermis). Good quality of prediction was obtained regardless of the target tissue. The standard errors of prediction obtained for the outer pericarp, intermediate layer, aleurone layer, and starchy endosperm quantification were, respectively, 3.4, 1.3, 3.4, and 4.6

FTIR and Raman signatures of wheat grain peripheral tissues

Corresponding author: [email protected] audienceHand-dissection of mature grains from three common wheat cultivars (Triticum aestivum L.: Caphorn, Crousty, and Recital) and one durum wheat (T durum Desf., Ardente) was performed to obtain pure samples of aleurone layer. hyaline layer, outer pericarp, and a composite layer made up of testa+inner pericarp. Vibrational spectral signatures were collected on both sides of the layers by ATR-FTIR and Raman spectroscopy. Spectra were compared with biochemical analysis on the same samples which allowed identification of specific composition patterns in each tissue regardless of the cultivar. Considering the low penetration depth of ATR-FTIR signal, the cuticles were evidenced on the external sides of outer pericarp, hyaline layer, and testa. Spectra from testa of red and white wheats were clearly distinguished. FTIR spectroscopy, combined with statistical analysis, was successful in identifying the specific spectral signature for each peripheral tissue of wheat grains. In the 1500-800 cm(-1) spectral region, multivariate models allowed accurate prediction of the histological origin of the pericarp, hyaline, and aleurone layers regardless of the analyzed side, and the testa but with a lower performanc

Analyse de la morphologie de particules par imagerie optique

Avant tout usage de la matière végétale, celle-ci est en règle générale broyée dans un objectif de densification, voir fractionnée pour obtenir des particules aux fonctions/propriétés ciblées. Le fractionnement de matières lignocellulosiques telles que les pailles de maïs, tiges de miscanthus, produit des particules de morphologie très poly disperse. La distribution des paramètres morphologiques est un critère important, soit pour la compréhension et le pilotage des procédés de fractionnement, soit pour l’utilisation de ces particules, par exemple dans la production de matériaux. Il est donc important d’avoir accès aux caractéristiques morphologiques des particules telles que leur taille et leur allongement.Nous nous sommes intéressés à deux systèmes de caractérisation utilisant des techniques d’acquisitions d’images optiques, mais dont la présentation de l’échantillon est différente : le système Qicpic (Sympatech) qui acquière avec une caméra rapide les images des particules qui sont dans un flux continu et le système MorphoG4 (Malvern) qui fait une acquisition d’image par transmission après dispersion sur une plaque en verre avec une faible pression. Pour les deux systèmes, l’analyse d’image se fait en système « boîte noire », mais nous avons ensuite accès à l’image de chaque particule identifiée et à des représentations de la dispersion des particules en fonction des diverses caractéristiques morphologiques.Notre démarche est de comparer les deux équipements à l’aide de deux poudres assez grossières (longueur desparticules pouvant être supérieure au mm). Compte tenu de la taille et de la forme allongée de ces particules les techniques de granulométrie laser ne sont pas les mieux adaptées. Ces deux fractions contrastées sont issues du broyage de tiges de miscanthus via deux procédés de broyage différents et leur taille de particules est dans une gamme équivalente (200μm –800μm, obtenue par tamisage). Nous utilisons les équipements dans les conditions préconisées par les fournisseurs et avec un maximum d’étapes automatisées, qui seront idéalement utilisées pour la caractérisation des fractions futures. Les distributions volumique (ou en nombre) des paramètres morphologiques ont ainsi été comparée afin d’évaluer l’influence du mode de présentation sur les résultats obtenus

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

Chemical treatment for the degradation of the mechanical properties of miscanthus stems to facilitate fragmentation

Chemical treatment for the degradation of the mechanical properties of miscanthus stems to facilitate fragmentation. 8. Plant Biomechanics International Conference PBM

Relative amounts of tissues in mature wheat (Triticum aestivum L.) grain and their carbohydrate and phenolic acid composition

Hand dissection of mature grains from two common wheats (Triticum aestivum L., cv. Caphorn and cv. Crousty) were performed to quantitatively assess their tissue composition and to obtain homogeneous samples of embryonic axis, scutellum, starchy endosperm, aleurone layer, hyaline layer, outer pericarp and a composite layer made up of testa+hyaline layer+inner pericarp. Polymeric neutral sugar and phenolic acid contents of the samples were determined and used to identify specific composition patterns in each tissue irrespective of the cultivar. The scutellum and embryonic axis showed the lowest amount of carbohydrates with similar relative amounts of arabinose and xylose (Ara+Xyl), but the scutellum differed from the embryonic axis in its high phenolic acid, in particular ferulate dehydrodimer, content. The peripheral layers of the grains were mainly composed of cell wall polysaccharides, chiefly arabinoxylans but with differing structures. The hyaline layer was mostly composed of arabinoxylan with extremely low Ara/Xyl ratio (0.1), with high amounts of ferulic acid monomers and hence very weakly crosslinked. The aleurone layer differed from the outer pericarp by its much lower Ara/Xyl ratio and lower amounts of ferulic acid dimers and trimers. High proportions of ether-linked phenolic acids (released by alkali at 170 °C) were detected specifically in the seed coat and tissues in the crease region. The possible application of biochemical markers found in the various tissues to monitor wheat grain fractionation processes is discussed

Debranning kinetics of precooked durum wheat

Debranning kinetics of precooked [i]durum wheat[/i]. 19. ICC conference ICC201

Comparaison des méthodes AOAC 985.29, 2001.03 et 2009.01 pour le dosage des fibres alimentaires dans les produits céréaliers à base de blé

Cet article est issu d'un poster présenté aux 63èmes Journées Techniques des Industries Céréalières, octobre 2012Les fibres alimentaires sont des constituants de notre alimentation dont une plus forte consommation est encouragée. Dans ce contexte, il est nécessaire de disposer de dosages fiables à la fois pour quantifier l’apport en fibres des produits céréaliers mais aussi pour guider le développement de nouveaux produits plus riches en fibres permettant de répondre aux recommandations nutritionnelles. Dans cette étude, les principales méthodes de dosage des fibres totales ont été mises en œuvre sur des produits céréaliers à base de blé (grain, farine T55, issues, pain type 55, pain complet, pâtes complètes). Les résultats obtenus confirment que les valeurs en fibres totales (TDF, Total dietary fiber) de la méthode AOAC 985.29 correspondent aux valeurs en fibres de haute masse moléculaire (HMwDF) des méthodes 2001.03 et 2009.01. La fraction HMwDF n’inclut pas les oligosaccharides non digestibles, ni l’amidon résistant qui font partie de la définition des fibres alimentaires. La méthode 2009.01 permet d’évaluer l’ensemble des fibres alimentaires avec des paramètres de fidélité comparable aux méthodes 985.29 ou 2001.03. Son utilisation pour des produits fabriqués à partir de farine de type 55 a une forte incidence sur la teneur en fibres totales, en raison de la proportion plus importante dans ces produits d’oligosaccharides non digestibles (non pris en compte par AOAC 985.29) et d’amidon résistant (non pris en compte par AOAC 985.29 et 2001.03)

Arabinoxylan content and grain tissue distribution in wheat products are good predictors for the amount and quality of dietary fiber

Epidemiological studies have shown that high dietary fibre (DF) diets and whole grain consumption are associated with diminished risk of coronary heart disease, colon cancers, inflammatory bowel disease, and metabolic syndrome (Anderson et al., 2009). Cereals foods, with wheat as the main source in Europe, could be one of the pillars of a healthy diet and might help to increase the DF intake. In that context having reliable method to quantify the DF amount is crucial to characterize food product but also monitor the development of enriched cereal based products. DF measurements are based on sequential and gravimetric analyses mimicking human digestion. Such methods made of several steps are time-consuming and results obtained are still under debate (Hell et al., 2014). Wheat grain contains about 12-14% of fibres mainly located in the outer layers (from the aleurone layer to the pericarp). Considering this specific location, the tissue composition of different mill streams has been measured (as done by Hemery et al., 2009) and compared to their total DF amount measured with the AOAC 2009-01 method. Assuming that the most peripheral tissues are mainly constituted of DF, the tissue composition could be used to estimate the total DF content in mill streams. However such approach could not be extended to food products. Therefore, knowing that arabinoxylans (AX) are the main components of cell walls in the different tissue of the wheat grain, biochemical determination of AX content has been investigated as a possible predictor of DF content. A set of different wheat products, either mill streams and food products (bread, biscuits, pasta) more or less enriched in DF fractions extracted from wheat grains, have been characterized either for DF amount (by the AOAC 2009-01 method) and the AX content by gas chromatography of alditols acetates after sulfuric acid hydrolysis. A strong correlation (r2=0.99) has been observed between the AX and TDF contents, indicating that AX could be used as a good predictor of TDF as soon as wheat is the main source of cereal in the food product. Moreover, by adding a previous step including enzymatic hydrolysis with a xylanase (Saulnier & Quemener, 2009), a functional evaluation of DF is proposed based on the amount of AX released by the enzyme. Xylanase hydrolysable AX are supposed to be also released by microbiota’s enzymes in the gut and therefore an indicator for the proportion of fermentable DF in a tissue or a wheat based food. This assay opens the door for simple characterization of qualitative attribute of cereal DF