Pulsed laser ablation: A new approach to reveal wheat outer layer properties

Wheat bran layers: composition, structure, fractionation, and potential uses in foods

Wheat bran, the main by-product of dry milling of wheat, is currently mainly used in the animal feed industry, but has attracted attention as a food ingredient owing to its high dietary fiber and phytochemical contents, providing excellent physiological effects. The bran layers (aleurone layer, outer pericarp and intermediate layer) contain different compositions, structures, and nutrients, and have different properties. Each layer, when separated and isolated, potentially could find more extensive applications in foods. This triggered interest in isolating the bran layers using milling and wet- or dry-fractionation techniques based on their chemical or physical properties. The recent progress has allowed the production of commercial products from wheat bran layers, particularly aleurone-rich products, enhancing the value of wheat bran layers and their applications in food. The present review highlights the recent advances in studying the chemical composition including distribution of chemical components, physical structure, biopolymer matrix, and physicochemical properties of each wheat bran layer. Technologies to fractionate wheat bran layers and utilization of different bran layers in foods are discussed and reviewed, providing new strategies for improving the value of wheat bran and utilization of wheat bran in foods.

Toward the Genetic Basis and Multiple QTLs of Kernel Hardness in Wheat

Kernel hardness is one of the most important single traits of wheat seed. It classifies wheat cultivars, determines milling quality and affects many end-use qualities. Starch granule surfaces, polar lipids, storage protein matrices and Puroindolines potentially form a four-way interaction that controls wheat kernel hardness. As a genetic factor, Puroindoline polymorphism explains over 60% of the variation in kernel hardness. However, genetic factors other than Puroindolines remain to be exploited. Over the past two decades, efforts using population genetics have been increasing, and numerous kernel hardness-associated quantitative trait loci (QTLs) have been identified on almost every chromosome in wheat. Here, we summarize the state of the art for mapping kernel hardness. We emphasize that these steps in progress have benefitted from (1) the standardized methods for measuring kernel hardness, (2) the use of the appropriate germplasm and mapping population, and (3) the improvements in genotyping methods. Recently, abundant genomic resources have become available in wheat and related Triticeae species, including the high-quality reference genomes and advanced genotyping technologies. Finally, we provide perspectives on future research directions that will enhance our understanding of kernel hardness through the identification of multiple QTLs and will address challenges involved in fine-tuning kernel hardness and, consequently, food properties.

Laser-induced breakdown spectroscopy and chemometrics: a novel potential method to analyze wheat grains

Laser-induced breakdown spectroscopy (LIBS) has been widely used to evaluate the elemental composition (e.g., minerals or metal accumulation) on vegetal tissues. The main objective of this work was to differentiate wheat outer tissues during the grain ablation using LIBS and univariate/multivariate analysis. A high resolution spectrometer and a Nd:YAG laser (532 nm, 5 ns) was first used in order to easily identify atomic wheat emission lines. Then a pulsed excimer laser ArF (193 nm, 15 ns) and a compact fiber optic spectrometer was used to acquire LIBS spectral data from each pulse. Univariate and multivariate analyses (MW2D, PLS-DA) were carried out to provide more in depth information from the LIBS experiment. The number of pulses needed to ablate wheat tissues was successfully predicted by the supervised pattern recognition procedure. LIBS used in conjunction with multivariate analysis could be an interesting technique for rapid structural analysis of vegetal material.