Aleurone Research Articles

The Wheat Aleurone Layer: Optimisation of Its Benefits and Application to Bakery Products.

The wheat aleurone layer is, according to millers, the main bran fraction. It is a source of nutritionally valuable compounds, such as dietary fibres, proteins, minerals and vitamins, that may exhibit health benefits. Despite these advantages, the aleurone layer is scarce on the market, probably due to issues related to its extraction. Many processes exist with some patents, but a choice must be made between the quality and quantity of the resulting product. Nonetheless, its potential has been studied mainly in bread and pasta. While the nutritional benefits of aleurone-rich flour addition to bread agree, opposite results have been obtained concerning its effects on end-product characteristics (namely loaf volume and sensory characteristics), thus ensuing different acceptability responses from consumers. However, the observed negative effects of aleurone-rich flour on bread dough could be reduced by subjecting it to pre- or post-extracting treatments meant to either reduce the particle size of the aleurone's fibres or to change the conformation of its components.

Barley metallothionein isoforms, MT2b2 and MT4, differentially respond to photohormones in barley aleurone layer and their recombinant forms show different affinity for binding to zinc and cadmium.

Metallothioneins (MTs) are metal-binding proteins that have important roles in the homeostasis of heavy metals. In this study, the two MT genes was studied in response to phytohormones using the barley aleurone layer as a kind of model system. The aleurone layer was isolated from barley embryo-less half grains and was incubated for 24h with different phytohormones. Based on the results the genes encoding HvMT2b2 and HvMT4 were down-regulated through gibberellic acid (GA), while they were and up-regulated through salicylic acid (SA). Despite this, these two genes were differentially expressed to other hormones. Furthermore, the proteins HvMT2b2 and HvMT4 were heterologous expressed as GST-fusion proteins in E. coli. The HvMT4 and HvMT2b2 heterologous expression in E. coli gives rise to 10- and 3-fold improvements in the accumulation capacity for Zn2+, respectively. Whereas the transgenic E. coli strain that expresses HvMT2b2 could accumulate Cd2+ three-fold higher than control. The expression of HvMT4 did not affect the accumulation of Cd2+. HvMT4 which is known as seed-specific isoform seems to be able to bind to Zn2+ with good affinity and cannot bind Cd2+. In comparison, HvMT2b2 was able to bind both Zn2+ and Cd2+. Therefore HvMT4 could serve a noteworthy role in zinc storage in barley seeds. The expression of HvMT4 is induced by SA 30-fold, concerning the untreated aleurone layer. Such results could provide good insights for the assessment of the effects of phytohormones in the molecular mechanism involved in essential metal storage in cereal seeds.

Endophytic Bacteria Associated with Origanum heracleoticum L. (Lamiaceae) Seeds

Seed-associated microbiota are believed to play a crucial role in seed germination, seedling establishment, and plant growth and fitness stimulation, due to the vertical transmission of a core microbiota from seeds to the next generations. It might be hypothesized that medicinal and aromatic plants could use the seeds as vectors to vertically transfer beneficial endophytes, providing plants with metabolic pathways that could influence phytochemicals production. Here, we investigated the localization, the structure and the composition of the bacterial endophytic population that resides in Origanum heracleoticum L. seeds. Endocellular bacteria, surrounded by a wall, were localized close to the aleurone layer when using light and transmission electron microscopy. From surface-sterilized seeds, cultivable endophytes were isolated and characterized through RAPD analysis and 16S RNA gene sequencing, which revealed the existence of a high degree of biodiversity at the strain level and the predominance of the genus Pseudomonas. Most of the isolates grew in the presence of six selected antibiotics and were able to inhibit the growth of clinical and environmental strains that belong to the Burkholderia cepacia complex. The endophytes production of antimicrobial compounds could suggest their involvement in plant secondary metabolites production and might pave the way to endophytes exploitation in the pharmaceutical field.

Development of SNP Markers from GWAS for Selecting Seed Coat and Aleurone Layers in Brown Rice (Oryza sativa L.).

Ninety-five percent of the general nutrients in rice are concentrated in the rice bran and germ, and many nutrients such as vitamins, minerals, dietary fiber, and essential fatty acids, as well as antioxidants such as tocopherol, are lost during milling. In this study, we investigated the thickness of seed coat and aleurone layers using a 294 rice core collection, and found candidate genes related to thickness of seed coat and aleurone layers, by performing a genome wide association study (GWAS) analysis using whole genome resequencing data. Two primer pairs that can be used as high-resolution melting (HRM) markers were developed. As a result of genotyping BC2F2 individuals derived from a cross between “Samgwang” and “Seolgaeng”, and using corresponding HRM markers, it was possible to finally develop HRM markers for selecting seed coat and aleurone layer thickness. This is expected to be used as basic data for the application of gene editing using CRISPR/Cas9 technology and for establishing a breeding strategy for high eating quality rice using molecular genetic technology.

Construction of a novel Wheat 55K SNP array-derived genetic map and its utilization in QTL mapping for grain yield and quality related traits.

Wheat is one of the most important staple crops for supplying nutrition and energy to people world. A new genetic map based on the Wheat 55 K SNP array was constructed using recombinant inbred lines derived from a cross between Zhongkemai138 and Kechengmai2 to explore the genetic foundation for wheat grain features. This new map covered 2,155.72 cM across the 21 wheat chromosomes with 11,455 markers. And 2,846 specific markers for this genetic map and 148 coincident markers among different maps were documented, which was helpful for improving and updating wheat genetic and genomic information. Using this map, a total of 68 additive QTLs and 82 pairs of epistatic QTLs were detected for grain features including yield, nutrient composition, and quality-related traits by QTLNetwork 2.1 and IciMapping 4.1 software. Fourteen additive QTLs and one pair of epistatic QTLs could be detected by both software programs and thus regarded as stable QTLs here, all of which explained higher phenotypic variance and thus could be utilized for wheat grain improvement. Additionally, thirteen additive QTLs were clustered into three genomic intervals (C4D.2, C5D, and C6D2), each of which had at least two stable QTLs. Among them, C4D.2 and C5D have been attributed to the famous dwarfing gene Rht2 and the hardness locus Pina, respectively, while endowed with main effects on eight grain yield/quality related traits and epistatically interacted with each other to control moisture content, indicating that the correlation of involved traits was supported by the pleotropic of individual genes but also regulated by the gene interaction networks. Additionally, the stable additive effect of C6D2 (QMc.cib-6D2 and QTw.cib-6D2) on moisture content was also highlighted, potentially affected by a novel locus, and validated by its flanking Kompetitive Allele-Specific PCR marker, and TraesCS6D02G109500, encoding aleurone layer morphogenesis protein, was deduced to be one of the candidate genes for this locus. This result observed at the QTL level the possible contribution of grain water content to the balances among yield, nutrients, and quality properties and reported a possible new locus controlling grain moisture content as well as its linked molecular marker for further grain feature improvement.

Intact aleurone cells limit the hydrolysis of endogenous lipids in wheat bran during storage

This work aimed to elucidate the effect of aleurone cell integrity on the hydrolysis of endogenous lipids in wheat bran and flour. The distribution of lipases in the bran dissected layers (aleurone layer, outer pericarp and intermediate layer) and the lipid hydrolysis in the bran fractions and flour containing the aleurone cells with different integrity were investigated. The results indicated that 80% of the lipase activities in bran layers were associated with the aleurone layer. After centrifugal impact milling, the aleurone layer in commercial bran could be detached into the monolayer cell clusters with decreasing integrities as the particle size decreased. In the oil phase, intact aleurone cells did not limit the lipase activities in the bran fractions because the oil could penetrate into aleurone cells. During storage, the hydrolysis rates of endogenous lipids in the bran fractions and their mixed flour increased as the integrity of aleurone cells decreased; while after the aleurone cells were broken, the hydrolysis rates of endogenous lipids increased to be in line with the lipase activities in bran fractions, indicating the limitation of intact aleurone cells on lipid hydrolysis. These results gave a new understanding of the effect of aleurone cell structure on the interaction between lipases and lipids in wheat bran, and will facilitate the production of stable wheat bran and whole wheat flour.

The location of iron and zinc in grain of conventional and biofortified lines of sorghum

Sorghum is an important source of dietary iron (Fe) and zinc (Zn) in parts of Africa and India, but there is a need to increase their concentrations to meet dietary requirements. Grains of a genetically biofortified sorghum line (Parbhani Shakti) had higher concentrations of Fe and Zn than a control line (M35-1). Analysis at the tissue level by histochemical staining and at the cellular level using NanoSIMS showed that both minerals are concentrated in the aleurone layer and in the scutellum of the embryo, with Zn also being concentrated in the embryonic axis. However, NanoSIMS showed that “hot spots” of 56Fe+ and 64Zn+ were also present in the sub-aleurone and starchy endosperm cells. Most of these hot spots also contained 31P16O+ indicating that the Fe and Zn are present as phytates, as in the aleurone and scutellum cells. Low concentrations of 56Fe+ and 64Zn+ were also observed in the protein matrix of these cells.

Co-expression of transcription factors ZmC1 and ZmR2 establishes an efficient and accurate haploid embryo identification system in maize.

Because of their high efficiency during chromosome doubling, immature haploid maize (Zea mays L.) embryos are useful for doubled haploid production. The R1-nj marker is commonly used in doubled haploid breeding and has improved the efficiency of haploid identification. However, its effectiveness is limited by genetic background and environmental factors. We addressed this technical challenge by developing an efficient and accurate haploid embryo identification marker through co-expression of two transcription factor genes (ZmC1 and ZmR2) driven by the embryo-aleurone-specific bidirectional promoter PZmBD1 ; these factors can activate anthocyanin biosynthesis in the embryo and aleurone layer during early seed development. We developed a new haploid inducer, Maize Anthocyanin Gene InduCer 1 (MAGIC1), by introducing the transgenes into the haploid inducer line CAU6. MAGIC1 could identify haploids at 12 days after pollination, which is nine days earlier than CAU6. Importantly, MAGIC1 increased haploid identification accuracy to 99.1%, compared with 88.3% for CAU6. In addition, MAGIC1 could effectively overcome the inhibition of anthocyanin synthesis in some germplasms. Furthermore, an upgraded anthocyanin marker was developed from ZmC1 and ZmR2 to generate MAGIC2, which could identify haploids from diploids due to differential anthocyanin accumulation in immature embryos, coleoptiles, sheaths, roots, leaves, and dry seeds. This haploid identification system is more efficient and accurate than the conventional R1-nj-based method, and it simplifies the haploid identification process. Therefore, this system provides technical support for large-scale doubled haploid line production.

Pre-gelatinization and cellulase addition improve fermentation performance and antioxidant activity of black rice wine.

Black rice contains a variety of bioactive substances that contribute to the high nutritional value of black rice wine (BRW). However, the dense bran layer of black rice retards the fermentation rate and reduces the dissolution of active components. Hence, this study aims to investigate the effects of pre-gelatinization (PG) before cooking and cellulase (CE) addition during fermentation on the fermentation performance of BRW and its antioxidant activity. PG combined with CE treatments (PGCE) increases the alcohol content, free amino acid content, volatile flavor content and total antioxidant activity of BRW by 90.81%, 15.36%, 38.05% and 19.56%, respectively, compared with the control group. Scanning electron microscopy, low-field nuclear magnetic resonance and texture properties analysis indicate that PG treatment increases gelatinization degree of starch during cooking, decreases bound water content in cooked black rice and promotes unbound water release. CE destroys the aleurone layer structure, facilitates the release of unbound water and the exposure of rice starch, thus increasing the reaction area and extravasation content significantly, which is beneficial to microbial growth and fermentation. Incomplete aleurone layer also promotes the dissolution of anthocyanins, phenols and other active substances, increasing the antioxidant activities of BRW. PG and CE treatments reduce the fermentation time and improve the quality of BRW by destroying the black rice structure. © 2022 Society of Chemical Industry.

Economic valuable indicators of winter bread wheat accessions with different pigmentation of kernels

Purpose and objectives. To screen modern varieties and breeding lines of winter bread wheat with different pigmentation of grain for valuable economic and biochemical characteristics, determining the stability of their expression.
 Materials and methods. Sixty-six winter wheat accessions, including 2 white-grained accessions, 3 accessions with violet kernels, 6 accessions with a blue aleurone layer (the other accessions were red-grained), were studied. The field experiments were conducted in 2017–2020 in compliance with the methods of qualification examination of plant varieties. The total content of phenolic compounds, total antioxidant activity, as well as contents of anthocyanins and micronutrients were determined. Descriptive statistics, correlation, and analysis of variance were used to statistically process the data obtained.
 Results and discussion. The accessions with a pigmented aleurone layer formed ears 4–7 days later than the check variety and were not resistant to diseases. Plants were taller than 109 cm in Ferugineum 1239, Kharkivska 63, Germakianum 2005-87, Viridiferrugineum 2022-87, BLUExRED, Vavilovy 2004-87, Chornobrova, and Chornozerna. It was the productive stem density (which was less than 6.5 points in the accessions with atypical grain color) that determined the yield level. The accessions yielding over 9 t/ha were selected of the red-grained varieties; most of them had been bred in Ukraine. The accessions with blue and violet kernels gave significantly lower yields, but they were characterized by high total content of phenols in meal (over 800 μg/g of gallic acid equivalent), high content of anthocyanins, and high total antioxidant activity (over 500 μg/g of chlorogenic equivalent).
 Conclusions. The accessions with atypical grain color were noticeable for high contents of biologically active substances, but they were significantly inferior to the commercial varieties in terms of yield due to low adaptability to the local conditions. By involving them in hybridization, we obtained material adapted to the conditions of Ukraine; however, further breeding is needed to create a commercial variety.

Gentle debranning as a technology to reduce microbial and deoxynivalenol levels in common wheat (Triticum aestivum L.) and its application in milling industry

In order to improve the hygienic characteristics of the wheat kernels and flours, gentle debranning technology was employed in this study. The physical, chemical and microbial modifications associated with the debranning of common wheat at a peeling rate of 0–5% were examined. Results showed that 80.1% of microorganisms and 15.82% of deoxynivalenol were removed when 1.08% of the total weight of the grain was peeled. The breakage rate of wheats increased from 0.23% to 0.38%, and there was no significant difference in hardness index compared with unpeeled kernels. Microstructure analysis showed an evenly removal of majority of outer pericarp (thickness of 25–35 μm), while the middle layer and aleurone layer remained intact. A further increase of debranning level led to moderate reduction of contamination but the mechanical strength of kernels decreased sharply. Therefore, gentle debranning at a peeling rate of 1.08% was deemed appropriate for milling industry. A significant decrease in ash content was observed for the three commercial flours, which could generate economic benefits. At the same time, the microbial contents of wheat products decreased by 23.0%–41.3%, and the deoxynivalenol contents decreased by 11.78%–20.75%. This study demonstrated the possibility of employing gentle debranning for reducing contaminants in wheat without compromising the milling characteristics.

Insights into the Regulation of Rice Seed Storability by Seed Tissue-Specific Transcriptomic and Metabolic Profiling.

Non-dormant seeds are continuously aging and deteriorating during storage, leading to declining seed vigor, which is a challenge for the rice seed industry. Improving the storability of seeds is of great significance to ensure the quality of rice and national food security. Through a set of chromosome segment substitution lines population constructed using japonica rice NIP as donor parent and indica rice ZS97 as recurrent parent, we performed seed storability QTL analysis and selected four non-storable NILs to further investigate the storability regulatory mechanisms underlying it. The seeds were divided into four tissues, which were the embryo, endosperm, aleurone layer, and hull, and tissue-specific transcriptome and metabolome analyses were performed on them. By exploring the common differentially expressed genes and differentially accumulated metabolites, as well as the KEGG pathway of the four non-storable NILs, we revealed that the phenylpropanoid biosynthesis pathway and diterpenoid biosynthesis pathway played a central role in regulating seed storability. Integrated analysis pinpointed 12 candidate genes that may take part in seed storability. The comprehensive analysis disclosed the divergent and synergistic effect of different seed tissues in the regulation of rice storability.

Progress in hybrid wheat research in Sichuan and future prospects

<p indent="0mm">Sichuan Province is an important wheat-producing region in China. Breeding of hybrid wheat and research related to this topic have been conducted for more than <sc>50 years</sc> in Sichuan. Both three-line and two-line methods have been used for breeding. Three-line hybrid wheat has been developed mainly using cytoplasmic male sterility (CMS) systems derived from other wild relatives. Among them, the <italic>Triticum timopheevii</italic>-based CMS (T-type) system is considered to be the best, and has therefore attracted most attention. Fertility restoration in lines carrying the <italic>timopheevii </italic>cytoplasm is often only partial, so different crossing and selection methods have been proposed to pyramid two or more <italic>Rf</italic> genes in restorer lines. However, this can be difficult to track because there is a lack of functional markers or associated molecular markers. Various restorer lines and combinations have been developed and tested, but no new commercial varieties have been released in Sichuan. The recent cloning of <italic>Rf1</italic> and <italic>Rf2</italic> genes has laid the foundation to develop effective restorer lines that may promote hybrid wheat breeding using the T-type three-line system. Hybrid wheat breeding programs based on the two-line system have generally been more successful in Sichuan. Two systems, photoperiod and temperature-sensitive genic male sterility (PTGMS) and chemical-hybridizing agent-induced male sterility (CHAMS), have been used for two-line hybrid wheat breeding. Mianyang 32 and Mianzamai 168, two hybrid wheat varieties developed using the PTGMS system, have been approved through national yield trials, and another two, Mianzamai 512 and Mianzamai 638, have been approved through provincial yield trials. For the CHAMS system, different types of chemical agents have been screened to determine their effectiveness and suitable doses to induce male sterility, and two new hybrid wheat varieties, Chuanmai 59 and Chuanmai 69, have been approved for release. The Taigu genic dominant male sterile system has also been studied in Sichuan. A new male-sterile line was bred by adding a single rearranged chromosome carrying <italic>Ms2</italic>, <italic>Rht10</italic>, and the blue aleurone layer gene from 4E (<italic>Agropyron elongatum</italic>). When this type of male-sterile line is crossed with a restorer line, about 20% of the progeny are male-sterile lines with short plant height and blue aleurone markers. This demonstrates the low reproduction coefficient of this sterile line. Another problem is the ability to maintain the integrity of the monosomic chromosome during meiosis. Until now, this system has not been used successfully to breed new hybrid wheat varieties in Sichuan. To summarize, there have been some important achievements in hybrid wheat breeding and research in Sichuan. For the sustainable development of hybrid wheat in Sichuan, it is important to improve the existing technical systems and develop and use new hybrid wheat breeding systems. By comparing the advantages and disadvantages of various hybrid wheat systems and combining them with new wheat production practices, we can develop strategies to further improve hybrid wheat in the future from the aspects of heterosis development and utilization, persistent disease resistance, economic benefits, and high yield and quality.

Anaerobiosis modulation of two phytoglobins in barley (Hordeum vulgare L.), and their regulation by gibberellin and abscisic acid in aleurone cells

The transcript levels of the phytoglobin (Pgb) genes Pgb1 and Pgb3, and the protein content of Pgb1 were responsive to anaerobiosis in several tissues of barley (Hordeum vulgare L.). Oxygen deficiency induced the level of both Pgb transcripts and protein in aleurone layers and coleoptiles, as well as up-regulated both Pgb1 and Pgb3 in leaves, apexes and more strongly in roots of barley seedlings. In O2-depleted aleurone cells the induction of the Pgb transcript-protein pair was reversed by re-supplying O2. Based on this observation, it is suggested that Pgb1 and Pgb3 are inducible in all tissues. In aleurone cells, gibberellic acid (GA) induced Pgb1 and Pgb3 together with α-amylase, whereas abscisic acid (ABA) eliminated the GA stimulating effects on both α-amylase and Pgb1 and Pgb3 expression. While GA had no effects on alcohol dehydrogenase (Adh1, Adh2 and Adh3) transcripts, ABA induced all three Adh genes. It is concluded that Pgb and α-amylase in seeds are regulated reciprocally with the ethanolic fermentation pathway, and that Pgb induction is mediated by GA. Nitric oxide turnover and scavenging mediated by Pgb represents an important alternative to fermentation under anoxia.

Significance of seed morphology and anatomy in the systematics of Musaceae

AbstractThe paper deals with the seed morphology and anatomy of 32 wild Indian Musaceae by using light microscopy (LM) and scanning electron microscopy (SEM). This is the first comprehensive investigation into the seed micro-morphological and anatomical aspects of two genera of the family. Seed characters including shape, size, surface sculpturing (LM and SEM), seed coat thickness, layer characters and chalazal chamber column were considered. Seed characters play a significant role in the delimitation of taxa as they are more stable than vegetative (anatomical) and pollen features. Four types of seeds (oblate, ovoid, sub-globose and ellipsoid) were observed in the family, oblate seeds being the most common. LM revealed that most of the seeds have verrucate surface sculpturing, but some are smooth-verrucate or smooth. Seed size also plays an important role in the identification of the taxa to some extent. Number of layers and seed coat thickness are directly proportional to seed size. However, the thickness of endotesta, tegmen and inner endosperm layers (aleurone layers) differ in small and large seeds. The present study revealed eight types of outer sculpturing and three inner sculpturing patterns with diverse nature of anticlinal and periclinal cell walls. Based on the seed characters, a phenetic analysis was also carried out.

Localisation of iron and zinc in grain of biofortified wheat

The dietary contributions of iron (Fe) and zinc (Zn) from cereals are determined by concentrations, locations and chemical forms. A genetically biofortified wheat line showed higher concentrations of Zn and Fe than three control lines when grown over two years. The mineral distributions determined using imaging (histochemical staining and LA-ICP-MS), sequential pearling and hand dissection showed no consistent differences between the two lines. Fe was most abundant in the aleurone layer and the scutellum and Zn in the scutellar epithelium, the endosperm transfer cells and embryonic axis. Pearling fractions showed positive correlations between the concentration of P and those of Zn and Fe in all fractions except the outermost layer. This is consistent with Fe and Zn being concentrated in phytates. Developing grains showed decreasing gradients in concentration from the proximal to the distal ends. The concentrations of Fe and Zn were therefore higher in the biofortified line than the control lines but their locations did not differ.

Proteolytic activities and profiles as useful traits to select barley cultivars for beer production.

Barley malting depends on hydrolytic enzymes that degrade storage macromolecules. Identifying barley cultivars with proteolytic activity that guarantees appropriate foaming, flavor, and aroma in the beer is of great importance. In this work, the proteolytic activity and profiles of brewing malt from Mexican barley cultivars were analyzed. Data showed that Cys- (at 50°C) and Ser-proteases (at 70°C) are the major contributors to proteolytic activity during mashing. Essential amino acids, necessary for fermentation and production of good flavor and aroma in beer, were detected at the end of mashing. According to our results, Mexican cultivar HV2005-19 exhibits similar proteolytic activities as those from cultivar Metcalfe, which is one of the most utilized for the brewing industry. Moreover, we propose Cys- and Ser-proteases as biochemical markers during mashing at 50 and 70°C, respectively, to select barley cultivars for beer production. PRACTICAL APPLICATIONS: Proteolytic activity, which depends on activation and de novo synthesis of proteases in the aleurone layer of barley seeds, is crucial in beer production. Identifying new barley varieties that have optimal proteolytic activities is of great interest for genetic improvement programs. In this study, we propose the variety HV2005-19 as a genotype with Cys- and Ser-proteases activity similar to that from Metcalfe, which is a top variety in the brewing industry.

Functional and physicochemical properties of milled and microfluidized bulgur and chickpea brans

Dietary fiber plays a crucial role in human diet due to their health-promoting effects. Cereal brans are widely used for fiber enrichment of bakery products; however, their high phytic acid content, mostly localized in the aleurone layer, lowers the nutritional value of the end-product. Therefore, the functional and physicochemical properties of two aleurone-free brans, bulgur and chickpea brans, were investigated as alternative fiber sources. Furthermore, effect of particle size reduction by means of milling and the microfluidization on these properties were determined. The results indicated that these two by-products of milling industry are valuable fiber sources with high amounts of phytochemicals and low phytic acid content. The applied microfluidization process enhanced physicochemical properties along with their functional properties, altered the ratio between insoluble and soluble fiber, dramatically increased phenolic compounds content and antioxidant activity; however, more importantly, it showed that it is possible to degrade phytic acid with microfluidization process.

Correlation of microstructure, pore characteristics and hydration properties of wheat bran modified by airflow impact mill

Strategies that could modify the structure of wheat bran by micronization are of great interest to improve its industrial application. The correlation between microstructure, pore characteristics and hydration properties of plant-scale, tissue-scale and cellular-scale wheat bran modified by airflow impact mill (AFIM) was investigated. AFIM treatment mainly caused different structural disruption of micropores in pericarp and aleurone layer, which significantly increased the soluble dietary fiber content, water-soluble index, whiteness and suspension stability of AFIM-treated wheat bran, but had a negative effect on its hydration properties (including water retention capacity, swelling capacity and oil retention capacity). Pearson correlation analysis indicated that the water retention capacity of wheat bran was significantly correlated with the percentage of microporous at the cellular level (r = − 0.99) and the tissue level (r = 0.72). These results could guide the application of different scales wheat bran in food systems.

Estimating the effect of low-temperature stress on the spatial distribution patterns of protein in wheat grains

As the major component determining wheat flour quality, protein is unevenly distributed in different grain fractions. In this study, mature wheat grains were pearled into nine fractions from the outer to the inner layers. The effects of low-temperature intensity, frequency and occurrence time on the spatial distribution patterns of grain protein were analyzed. The highest and lowest protein contents were observed in the aleurone and innermost endosperm layers under different low-temperature conditions. The contents of protein in the whole grains and each fraction were enhanced by low-temperature, and the enhancement was more obvious under low temperature applied at the booting stage. Compared with low temperature applied only at the booting stage, multiple low temperatures decreased the increase in protein content in wheat grains, which indicated that low-temperature pretreatment at the jointing stage could partly offset the effects of low temperatures on grain protein. In addition, significant linear relationships were observed between the accumulated cold degree days (ACDD) and the protein content in the whole grains and most fractions, which indicated that ACDD could be used to quantify the effect of low temperature on grain protein. Furthermore, a comparison of the relationships between grain protein and two types of ACDD indicated stronger correlations between canopy temperature-based ACDD (ACDDc) and the protein content in the outer and middle layers, whereas stronger correlations were observed between air temperature-based ACDD (ACDDa) and the protein content in the inner layers, which means that we should not only use the air temperature to quantify the effect of low temperature on the protein content distribution of wheat; we also need to consider the canopy temperature that is more closely related to crop development. The results provide an effective method for evaluating the effect of low-temperature stress on grain quality and a novel view for optimizing the utilization of wheat flour under low-temperature condition.