NanoLC-MS/MS protein analysis on laser-microdissected wheat endosperm tissues: A comparison between aleurone, sub-aleurone and inner endosperm

Wheat kernel proteins are not homogeneously distributed throughout the endosperm. The goal of this study was to investigate the relative differences in protein composition between the aleurone, sub-aleurone and inner endosperm. Using laser microdissection followed by nanoLC-MS/MS, an innovative method combining high spatial specificity and analytical selectivity in sample-limited situations, 780 proteins were detected and classified by function. A higher proportion of gluten proteins was detected in the sub-aleurone than inner endosperm. Composition-wise, gluten from the sub-aleurone is relatively more enriched in ω-gliadins but impoverished in LMW-GS and γ-gliadins. While a basic set of albumins and globulins was detected in all three microdissected endosperm tissues, specific proteins, like puroindoline B, displayed a gradient. This study provides indications that both histological origin and relative positioning of the tissues drive the protein distribution. Knowledge of this protein distribution offers significant opportunities for the wheat manufacturing industry. Data available via ProteomeXchange, identifier PXD038743.

The Wheat Starchy Endosperm Protein Gradient as a Function of Cultivar and N-fertilization Is Reflected in Mill Stream Protein Content and Composition

Within the wheat starchy endosperm, the protein content increases biexponentially from the inner to outer endosperm. Here, we studied how this protein gradient is reflected in mill fractions using three cultivars (Claire, Apache, and Akteur) grown without and with N-fertilization (300 kg N ha-1). The increasing protein content in successive break fractions was shown to reflect the protein gradient within the starchy endosperm. The increasing protein content in successive reduction fractions was primarily due to more aleurone contamination and protein-rich material being harder to reduce in particle size. The miller's bran fractions had the highest protein content because of their high sub-aleurone and aleurone content. Additionally, the break fractions were used to deepen our understanding of the protein composition gradient. The gradient in relative gluten content, increasing from inner to outer endosperm, was more pronounced without N-fertilization than with and reached levels up to 87.3%. Regarding the gluten composition gradient, no consistent trends were observed over cultivars when N-fertilization was applied. This could, at least partly, explain why there is no consensus on the gluten composition gradient in the literature. This study aids millers in managing fluctuations in the functionality of specific flour streams, producing specialized flours, and coping with lower-quality wheat.

Investigating the Contribution of Blending on the Dough Rheology of Roller-Milled Hard Red Wheat

The flour functionality and particle size distribution of wheat flour obtained on roller milling are dependent on the type of wheat, tempering conditions, and milling conditions. In this study, the impact of the tempering conditions (moisture and time) on the chemical and rheological properties of flour from blends of hard red wheat were analyzed. The wheat blends B1-25:75 (hard red spring (HRS)/hard red winter (HRW)), B2-50:50, and B3-75:25, which were tempered to 14%, 16%, and 18% for 16, 20, and 24 h, respectively, were milled using a laboratory-scale roller mill (Buhler MLU-202). Protein, damaged starch, and particle characteristics were influenced by blending, tempering, and milling streams. For all the blends, the protein content varied significantly among the break flour streams; the damaged starch content varied greatly in the reduction streams. The increased damaged starch content of the reduction streams proportionally increased water absorption (WA). Higher proportions of HRS in the blends significantly decreased the pasting temperature of the dough, as measured using Mixolab. Principal component analysis proved that the protein content was the key determinant in particle characteristics, WA, and pasting properties of the flour, especially in blends with a higher proportion of HRS.

Influence of Wheat Flour Milling Yield on Physicochemical, Microbial, and Antioxidant Properties of Korea Wheat (Triticum aestivum L. var. Jokyoung)

The physicochemical, microbial, and antioxidant properties of a Korean wheat variety (Jokyoung) were measured according to milling yield (60–90%) by adding fractions from millstreams. As the milling yield increased, the wheat flour showed low quality on physicochemical properties in general. Significant differences in proximate analysis, color, solvent retention capacity, pasting property, and antioxidant activity were observed as the yield increased to maximize the production of wheat flour from wheat kernels. Adding clear flour and shorts did not significantly affect the quality of the wheat flour in comparison with straight flour samples. However, as brans were added to the flour portion, the wheat flour quality parameters decreased significantly in color, solvent retention capacity, and pasting properties. On the other hand, antioxidant properties increased as brans were added. Maximizing wheat flour yield is a key to minimizing the production cost of Korean wheat flour, which is approximately three times more expensive than imported wheat flour. Adding clear flour and a certain portion of shorts did not seem to significantly influence the overall quality of wheat flour from Korean domestic wheat variety.

Temperature and nitrogen supply interact to determine protein distribution gradients in the wheat grain endosperm

Gradients exist in the distribution of storage proteins in the wheat (Triticum aestivum) endosperm and determine the milling properties and protein recovery rate of the grain. A novel image analysis technique was developed to quantify both the gradients in protein concentration, and the size distribution of protein bodies within the endosperm of wheat plants grown under two different (20 or 28 °C) post-anthesis temperatures, and supplied with a nutrient solution with either high or low nitrogen content. Under all treatment combinations, protein concentration was greater in the endosperm cells closest to the aleurone layer and decreased towards the centre of the two lobes of the grain, i.e. a negative gradient. This was accompanied by a decrease in size of protein bodies from the outer to the inner endosperm layers in all but one of the treatments. Elevated post-anthesis temperature had the effect of increasing the magnitude of the negative gradients in both protein concentration and protein body size, whilst limiting nitrogen supply decreased the gradients.

Spatial patterns of gluten protein and polymer distribution in wheat grain

The starchy endosperm is the major storage tissue in the mature wheat grain and exhibits quantitative and qualitative gradients in composition, with the outermost cell layers being rich in protein, mainly gliadins, and the inner cells being low in protein but enriched in high-molecular-weight (HMW) subunits of glutenin. We have used sequential pearling to produce flour fractions enriched in particular cell layers to determine the protein gradients in four different cultivars grown at two nitrogen levels. The results show that the steepness of the protein gradient is determined by both genetic and nutritional factors, with three high-protein breadmaking cultivars being more responsive to the N treatment than a low-protein cultivar suitable for livestock feed. Nitrogen also affected the relative abundances of the three main classes of wheat prolamins: the sulfur-poor ω-gliadins showed the greatest response to nitrogen and increased evenly across the grain; the HMW subunits also increased in response to nitrogen but proportionally more in the outer layers of the starchy endosperm than near the core, while the sulfur-rich prolamins showed the opposite trend.

Marker-assisted selection of high molecular weight glutenin alleles related to bread-making quality in Iranian common wheat (Triticum aestivum L.)

Bread-making quality in hexaploid wheats is a complex trait. It has been shown that the amount and composition of protein can influence dough rheological properties. The high-molecular-weight (HMW) glutenins are encoded by a complex locus, Glu-1, on the long arm of group-1 homoeologus chromosome of the A, B and D genomes. In this work we used PCR-based DNA markers as a substitution tool to distinguish wheat bread-making quality. We detected PCR-based DNA markers for coding sequence of Glu-A1x, Glu-B1x and Glu-D1x to be 2300 bp, 2400 bp and 2500 bp respectively. DNA markers related to coding sequence of Glu-A1y, Glu-B1y and Glu-D1y were; 1800 bp, 2100 bp and 1950 bp, however, the repetitive region of their coding sequence were shown to be about 1300 bp, 1500 bp and 1600 bp. The results demonstrate that the size variation was due to different lengths of the central repetitive domain. Good or poor bread-making quality in wheat is associated with two allelic pairs of Glu-D1, designated 1Dx5-1Dy10 and 1Dx2-1Dy12. The 1Bx7 allele has moderate-to-good quality score. The specific DNA markers, of 450 bp, 576 bp, 612 bp and 2400 bp respectively were characterized for 1Dx5, 1Dy10, 1Dy12 and 1Bx7 alleles. These markers are very important in screening of wheat for bread-making quality.

Suitability of spring wheat varieties for the production of best quality pizza

The selection of appropriate wheat cultivars is an imperative issue in product development and realization. The nutritional profiling of plants and their cultivars along with their suitability for development of specific products is of considerable interests for multi-national food chains. In this project, Pizza-Hut Pakistan provided funds for the selection of suitable newly developed Pakistani spring variety for pizza production. In this regard, the recent varieties were selected and evaluated for nutritional and functional properties for pizza production. Additionally, emphasis has been paid to assess all varieties for their physico-chemical attributes, rheological parameters and mineral content. Furthermore, pizza prepared from respective flour samples were further evaluated for sensory attributes Results showed that Anmool, Abadgar, Imdad, SKD-1, Shafaq and Moomal have higher values for protein, gluten content, pelshenke value and SDS sedimentation and these were relatively better in studied parameters as compared to other varieties although which were considered best for good quality pizza production. TD-1 got significantly highest score for flavor of pizza and lowest score was observed from wheat variety Kiran. Moreover, it is concluded from current study that all wheat varieties except TJ-83 and Kiran exhibited better results for flavor.

Influence of Wheat Milling on Low-hydration Bread Quality Developed by Sheeting Rolls

It is well known that milling influences the characteristics of flour and products made from it. This article analyzed the influence of milling on the quality of low-hydration bread. In general, milling influenced the quality of these products more than the type of wheat selected. Among the various mill streams, the last break and reduction streams produced lower quality bread and must be eliminated in milling. These streams had a higher protein and ash content, showing the presence of components of the outer layers of the grain. The flour was able to absorb more water, but had less extensibility in kneading and the dough generated was weaker due the poorer quality of its proteins and the influence of elements from the outer layers. Thus, bread made from these streams had smaller volume, had a firmer texture and had both darker crumb and crust. These differences, along with the effect of the kind of flour on the flavor and aroma of the bread, made it less acceptable than flour from the rest of the streams studied.