Bran Fractions Research Articles

Characterising the effect of commercial wheat grain milling methods on wheat bran characteristics

SummaryTo assess the effect of wheat milling or bran separation method, five wheat bran fractions, one from stone milling (SB), two from roller flour milling (coarse: RB1, fine: RB2), and two from grain pearling (0–3%: PB1, 3–6%: PB2) were analysed. Physiological properties provided good physical and flow characteristics of SB fraction; however, it was the darkest. Particle size was in the order of RB1 > SB > RB2 > PB1 > PB2. The fibre analysis showed the highest insoluble fibre components for RB1, PB1, and exceptionally higher soluble fibre for PB1. The protein, fat, ash, and starch content were highest for RB2 and PB2. Antioxidant properties followed the order PB2 > RB2 > PB1 > RB1 > SB. Pearled fractions (PB1 and PB2) showed better functional properties than others. SEM, XRD, and FT‐IR verified the changes in the properties of bran fractions. The characterisation data will find applications to help increase the usage of bran fractions in specific food products.

Overview of the Metabolite Composition and Antioxidant Capacity of Seven Major and Minor Cereal Crops and Their Milling Fractions.

Cereal grains play an important role in human health as a source of macro- and micronutrients, besides phytochemicals. The metabolite diversity was investigated in cereal crops and their milling fractions by untargeted metabolomics ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) of 69 samples: 7 species (barley, oat, pearl millet, rye, sorghum, triticale, and wheat), 23 genotypes, and 4 milling fractions (husk, bran, flour, and wholegrain). Samples were also analyzed by in vitro antioxidant activity. UHPLC-MS/MS signals were processed using XCMS, and metabolite annotation was based on SIRIUS and GNPS libraries. Bran and husk showed the highest antioxidant capacity and phenolic content/diversity. The major metabolite classes were phenolic acids, flavonoids, fatty acyls, and organic acids. Sorghum, millet, barley, and oats showed distinct metabolite profiles, especially related to the bran fraction. Molecular networking and chemometrics provided a comprehensive insight into the metabolic profiling of cereal crops, unveiling the potential of coproducts and super cereals such as sorghum and millet as sources of polyphenols.

Supplementation with soluble or insoluble rice-bran fibers increases short-chain fatty acid producing bacteria in the gut microbiota in vitro.

Studies have shown that a diet high in fiber and prebiotics has a positive impact on human health due largely to the fermentation of these compounds by the gut microbiota. One underutilized source of fiber may be rice bran, a waste product of rice processing that is used most frequently as an additive to livestock feed but may be a good source of fibers and other phenolic compounds as a human diet supplement. Previous studies focused on specific compounds extracted from rice bran showed that soluble fibers extracted from rice bran can improve glucose response and reduce weight gain in mouse models. However, less is known about changes in the human gut microbiota in response to regular rice bran consumption. In this study, we used a Simulator of the Human Intestinal Microbial Ecology (SHIME®) to cultivate the human gut microbiota of 3 different donors in conditions containing either soluble or insoluble fiber fractions from rice bran. Using 16S rRNA amplicon sequencing and targeted metabolomics via Gas Chromatography-Mass Spectrometry, we explored how gut microbial communities developed provided different supplemental fiber sources. We found that insoluble and soluble fiber fractions increased short-chain fatty acid production, indicating that both fractions were fermented. However, there were differences in response between donors, for example the gut microbiota from donor 1 increased acetic acid production with both fiber types compared with control; whereas for donors 2 and 3, butanoic acid production increased with ISF and SF supplementation. Both soluble and insoluble rice bran fractions increased the abundance of Bifidobacterium and Lachnospiraceae taxa. Overall, analysis of the effect of soluble and insoluble rice bran fractions on the human in vitro gut microbiota and the metabolites produced revealed individually variant responses to these prebiotics.

Distribution of antioxidants and phenolic compounds in flour milling fractions from hard red winter wheat

Mature wheat kernels contain three main parts: endosperm, bran, and germ. Flour milling results in multiple streams that are chemically different; however, the distribution of antioxidants and phenolic compounds has not been well documented in terms of conventional milling by-product streams. In this study, multiple analytical methods were used to investigate antioxidant activity and phenolic compound compositions of hard red winter wheat (whole ground wheat), the parts of a wheat kernel (bran, flour, germ), and wheat by-product streams (mill feed, red dog, shorts) for the first time. For each mill stream, phenolic compounds (total, flavonoid, and anthocyanin contents) were determined and antioxidant activities were evaluated with 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity, ferric reducing/antioxidant power (FRAP), and total antioxidant capacity assays. Significant differences (P < 0.05) were observed in phenolic concentrations among fractions of bran, flour, and germ milled from the same kernels and noted that germ accounts for the majority of antioxidant properties, whereas bran contains a substantial portion of phenolic compounds and anthocyanins. Mill feed was high in phenolic content (5.29 mg FAE/g), total antioxidant capacity (866 mg/g), and antioxidant activity (up to 75% DPPH inhibition and 20.26 μmol FeSO4/g). The comprehensive information on distribution of antioxidants and phenolic compounds provides insights for future human consumption of commonly produced co-products from flour milling, and for selecting and using different milling fractions to make foods with improved nutritional properties.

Optimization of emulsification conditions with rice bran concentrates for the preliminary formulation of potential vegan dressings and their characterization.

A fraction of rice bran (RB), generated during the brown rice polishing, is utilized to extract oil, resulting in defatted RB (DRB). The aim of this study was to optimize the emulsification conditions to enhance the value of this byproduct by formulating potential vegan dressings and characterizing them. Enzymatic hydrolysis of the starch present in DRB yields the DRB concentrate (DRBC). A central composite design was applied and the results were analyzed using response surface methodology to select optimal conditions for an oil-in-water emulsion formula. Two formulations were chosen: one corresponds to the optimal conditions, with 26.5% of oil and 73.5% of DRBC dispersion (eoptimal), and the other one with 21.7% of oil and 78.3% of dispersion (eED8). The eoptimal formulation exhibited significantly lower mean De Brouckere diameter (D4,3) value and higher viscosity when compared with eED8. For both emulsions, the particle size distribution and D4,3 remained unchanged during storage, whereas viscosity decreased, and backscattering (BS) increased. Initially, both emulsions exhibited solid viscoelastic behavior, which was partially lost during quiescent storage. The increase in BS was attributed to particle disaggregation, ultimately leading to the aforementioned change in rheological behavior. In conclusion, although the designed emulsions underwent microstructural changes, they were stable against gravitational separation. To improve stability during quiescent storage, it is suggested to incorporate a thickening agent. Hence, it is propose to procced with the development of a vegan dressing based on the eoptimal emulsion, as it exhibits superior physicochemical properties.

Impact of milling on the nutrients and anti-nutrients in browntop millet (Urochloa ramosa) and its milled fractions: evaluation of their flour functionality.

Browntop millet has gained popularity in recent years owing to its nutritional superiority and health benefits. However, the usage of browntop millet flours as ingredients in composite flours and functional foods is constrained due to a lack of information regarding the grain composition and its flour functionality. Therefore, the distribution of nutrients, anti-nutrients in browntop millet milled fractions and their flour functionality was evaluated in comparison to whole grain flour. Bran fraction comprised the highest protein (13.7%) and fat contents (27%) among other fractions. Pearling of dehulled grains considerably reduced phytic acid, saponins and flatulence-causing oligosaccharides in pearled grain flours. Besides, this led to the enrichment of soluble fibre, minerals, phenolics and trypsin inhibitors in bran fraction. Milling also impacted flour functionality. Despite its lower water holding ability, dehulled grain flour exhibited significantly higher oil absorption capacity than whole grain flour due to the removal of fibre-rich hull fraction. Although emulsion (45.2%) and foaming capacities (12.5%) were superior in bran flour, foam stability was greater in pearled grain flours. These findings suggest the potential utilisation of browntop millet milled flours as ingredients in the development of distinct food formulations and as partial substitutes to wheat flour in confectionary and bakery products. © 2024 Society of Chemical Industry.

Studies of phytochemical constituents by UPLC-QTOF-MS/MS of black hulless barley bran and its antioxidation and α-glucosidase inhibition effect

Anthocyanidins and flavonoids are important components in plant. In present study, the anthocyanidins and flavonoids in black hulless barley bran were identified by operating UPLC-QTOF-MS/MS. Among them, chrysoeriol 7-O-glucouronid, luteolin 7-O-glucouronid, chrysoeriol, and luteolin were quantified by using UPLC. Additionally, the total phenolic content (TPC), total flavonoids content (TFC) and total anthocyanin content (TAC) were determined. Furthermore, the antioxidant activity (via ferric reducing, DPPH and ABTS method) and α-glucosidase inhibition effect were estimated. From the results, fifty-one constituents comprised 19 anthocyanidins and 32 flavonoids were detected in hulless barley bran fractions. Wherein compounds 1 and 9–19 (belong to anthocyanidins), and 21, 25–32, 35–42, 44–50 (belong to flavonoids) were first identified in hulless barley. The contents of chrysoeriol 7-O-glucouronid luteolin 7-O-glucouronid, chrysoeriol and luteolin were higher in E80% than that of in E40%, but were not detected in E20%. Another, the TAC exhibited the trend of E40% > E80% > E20%, and the TPC and TFC showed same trend of E40% > E20% > E80%. The higher TPC and TFC showed stronger antioxidant activity. However, no significant correlation between TAC, TPC, TFC and α-glucosidase inhibitory activity was observed. These results provided the anthocyanidins and flavonoids information, antioxidant value and α-glucosidase inhibition potential, which could provide reference in the development of black hulless barley bran.

Composition, structural, physicochemical and functional properties of dietary fiber from different milling fractions of black rice bran

Black rice bran is a superior dietary fiber (DF) resource. However, the lack of specific distribution and functionality of DF in black rice bran has constrained its refined processing. This study divided black rice bran into five equal bran fractions (BF) by stepwise milling to obtain BF1(outermost layer) to BF5 (the innermost layer). The contents, structure, physicochemical and functional properties of DF in each bran fractions were investigated. The results revealed that the insoluble, soluble and total dietary fiber (IDF, SDF and TDF) contents were 17.52 ± 0.48 to 31.14 ± 0.96, 2.03 ± 0.20 to 3.86 ± 0.01 and 19.57 ± 0.28 to 34.61 ± 1.10 g/100 g dry basis, respectively. Compared to BF1, the TDF content of BF2–BF5 was reduced by 3.90, 3.20, 21.74 and 43.46%, respectively. The main monosaccharides in both IDF and SDF were xylose, glucose, arabinose and galactose. The molecular weight of SDF samples ranged from 17.19 ± 1.95 to 36.32 ± 0.80 kDa. The outer bran fractions (BF1–BF3) IDF exhibited higher water swelling, water retention, oil adsorption capacity, together with cholesterol and sodium nitrite adsorption capacity than those of inner bran fractions (BF4–BF5), owing to their lower crystallinity and well-developed porous structure. These results provide essential data for the development of black rice DF-based food processing with enhanced functional benefits.

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.

Effects of phenolic compounds of colored wheats on colorectal cancer cell lines

In this study, the different colored wheat brans were analyzed and compared for phenolic content (PC), phenolic compositions, and the total antioxidant capacity (TEAC) with methods based on the ability to eliminate radicals of 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH), and anthocyanin compositions. This study also aims to characterize the bioactive components of wheat grain genotypes as well as to test the protective and rescuer effects of their extracts on colorectal cancer (CRC) cell lines. PCs in the bound insoluble fraction of red wheat bran, blue wheat bran, and purple wheat bran were determined as 369.60, 446.95, and 486.79 mg gallic acid equivalents (GAE)/100 g wheat bran, respectively, while strong relationships were detected between PC and antioxidant activity (DPPH and ABTS) results. HPLC anal-ysis of phenolic extracts demonstrated that ferulic acid was determined as the dominant phenolic acid in the bound fractions of red, purple, and blue wheats. In the free fractions, p-coumaric acid (11.55 µg/100 g wheat bran) was the dominant phenolic acid for red wheat bran, whereas ellagic acid (14.72 and 11.55 µg/100 g wheat bran) was the highest phenolic acid for purple and blue wheat brans, respectively. In bound fractions, ferulic acid was the highest phenolic acid for red (988.39 µg/100 g wheat bran), purple (1948.76 µg/100 g wheat bran), and blue (2263.96 µg/100 g wheat bran) wheat brans. On the other hand, Cyanidin-3-O-glucoside chloride was the predominant anthocyanin in free extracts of purple and blue wheat brans. In line with the antioxidant activities and phenolic acid concentrations, the blue wheat bran extracts increased CRC cell viability nonsignificantly in HT-29 and HCT-116 cell lines, whereas purple wheat bran extract had a significantly higher (P = 0.0361) rescuer effect compared to vehicle control under 50 µM H2O2 concentration. In conclusion, the in vitro data here show that blue and purple wheat brans are posing a novel means to increase the defense of cells against oxidative stress and cell death.

Конверсия пшеничных отрубей в целевые продукты биосинтеза

A more efficient bioconversion of renewable plant resources is a priority in modern biotechnology. An important aspect of the processing and pretreatment of cellulose raw materials is to obtain a high content of reducing substances in the final product. The present research objective was to determine the optimal conditions for the chemical transformation of plant polymers to obtain biologically valuable substances. The research results will reduce the final cost of biotechnological production.&#x0D; This research featured wheat bran polymers treated with sulfuric acid and relied on a set of standard research methods. The degree of polymer conversion was tested on native and mechanically activated wheat bran fractions of 600, 200, and 100 microns. The kinetics of the high-temperature chemical hydrolysis was as follows: temperature – 120–130°C, sulfuric acid concentration – 0.6–0.9%, treatment time – 30–60 min, hydromodule – 1:8;9;10. The quantitative and qualitative composition of mono- and disaccharides of hydrolysates was determined using the high performance liquid chromatography method. &#x0D; The composition of wheat bran showed a low content of lignin (7.55%) and a high content of pentosans (17.9%). The highest content of reducing substances in hydrolysates was 640 mg/g bran. The optimal technological conditions with the highest content of reducing substances were as follows: hydromodulus – 1:10, temperature – 120°C, treatment time – 45 min, and sulfuric acid concentration – 0.9%. The greatest change in the content of mono- and disaccharides of hydrolysates belonged to pentoses: 78.2 mg/g of bran (in terms of xylose). The amount of easily hydrolysable carbohydrates and wheat bran fiber decreased by 80 and 19%, respectively.&#x0D; This research revealed the optimal parameters for the chemical hydrolysis of wheat bran to obtain biologically valuable carbohydrates. This area of research can be of practical use for producers of biofuels, chemicals, and food additives.

Wheat bran fractionation: Effect of steam explosion and hydrotropic extraction conditions on the recovery of sugars and lignin

Wheat bran, a major by-product of wheat processing, contains several valuable components that can serve as a potential feedstock for chemical production. This study presents a multiple-stage fractionation method, involving steam explosion and hydrotropic extraction, which were investigated with the goal of separating the main structural bran components: starch, protein, hemicelluloses, lignin, and cellulose. With prior de-starching and de-proteination, acid-catalysed steam explosion (STEX1: 218 °C, 8 min, 0.05 wt% H2SO4) solubilised up to 97% of the arabinoxylans. Higher monosaccharide yields arising from hemicelluloses were observed in the de-starched and de-proteinated bran than in untreated bran prior to steam treatment. Subsequent treatment using the 40% w/w hydrotrope solution, sodium xylene sulfonate (SXS), at 170 °C for 1 h (HEX1) showed lignin recovery of up to 42.6% from the steam-exploded bran, which was higher than 25.1% lignin recovery from the de-starched, de-proteinated and steam exploded bran. The lignin recovery values were slightly underestimated as some lignin ends up in the wash, which proved difficult to quantify. Finally, glucose monomer release during cellulose hydrolysis occurred most rapidly in the bran material that had undergone prior treatments of de-starching, de-proteination, steam explosion and hydrotropic treatment, with complete hydrolysis in less than 24 h for the de-starched, de-proteinated, steam exploded for both STEX1 and STEX3 (219 °C, 0.10 wt%, 14 min) and hydrotropically treated (HEX1). The selective release of wheat bran components in separate stages of the wheat-bran fractionating scheme provides a platform for further valorisation of each component into commercially relevant products. Structural elucidation of the recovered wheat bran lignin using 2D HSQC NMR revealed that oxidised syringyl (S′) units increased from 13.2 units per 100 C2 aromatic group (Ar) in bran without prior treatment, to 16.9 units/100 Ar in steam exploded bran and 18.2 units/100 Ar in de-starched, de-proteinated and steam exploded bran. The change in guaicyl (G) unit frequencies as well as the oxidised G units (G′) remained low across samples. As less oxidation is desired for further lignin valorisation, the results herein offer insights on future work for utilising wheat bran lignin.

Combining the genes of blue aleurone and purple pericarp in the genotype of spring bread wheat Saratovskaya 29 to increase anthocyanins in grain

Anthocyanins have health-promoting properties and are used to treat many diseases. Purple, blue and black wheat variety contain large quantities of anthocyanins in the outer kernel layers. Anthocyanins in wheat grains accumulate either in the pericarp, under the control of Pp genes, or in the aleurone layer (Ba genes). In black-grained (or deep purple) wheat, anthocyanins can be found in both the pericarp and the aleurone layer. Two lines of Saratovskaya 29 (S29) variety with a black grain color have been created to combine Pp and Ba genes controlling anthocyanins accumulation in one genotype. The lines have been obtained as a result of crossing near isogenic line i:S29Pp1Pp3PF and i:S29Pp1Pp3P with a blue-grain substituted line s:S294E(4B), and subsequent visual selection of plants with black grain coloring in the progeny F4-5. The presence of both pigments in the pericarp and aleurone layer was assessed using light microscopy. The total anthocyanin content in the bran fraction of the new obtained black-grained lines ranged from 145.5 to 241.3 μg/g compared to 135 μg/g of the blue-grain line s:S294E(4B), and 79.4 μg/g – i:S29Pp1PpP and 81.5 μg/g – i:S29Pp1PpPF. The developed lines may be of interest in breeding programs to increase anthocyanins in commercial varieties.

Phytochemical profiling of volatile and bioactive compounds in yellow mustard (Sinapis alba) and oriental mustard (Brassica juncea) seed flour and bran

The objective was to study the phytochemical profile of yellow (Sinapis alba) and oriental mustard (Brassica juncea) flour and bran fractions. The HS-SPME-GC/MS technique was used to determine the volatile profile. Up to 53 volatiles, including isothiocyanates, alkanes, alcohols, ketones and esters were identified in the mustard powders. In addition, the free and bound bioactive fraction was studied and the determination was performed by UHPLC-MS/MS. A total of 26 compounds (phenolic acids, flavonoids and glucosinolates) were identified in the mustard samples. Sinapis alba, including the bran fraction, was richer in p-hydroxybenzoic, ferulic and p-coumaric acids compared to Brassica juncea. In addition, the volatile profile in yellow mustard seeds, as analysed by HS-SPME-GC/MS, has been described for the first time in this work. The study of the principal components showed that according to the bioactive compounds profile it is possible to differentiate between the two mustard species analysed. Moreover, the bran fraction, as a by-product of the seed processing, is a matrix rich in bioactive compounds and could be applied for the recovery of polyphenols for agro-industrial or pharmaceutical application.

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.

Effect of psyllium husk and wheat mill bran fractions on the microstructure and mixograph characteristics of Arabic bread

When psyllium husk, wheat bran and germ was added, Incorporation of psyllium and wheat bran may affect the dough structure, dough rheology as well as the final quality of baked Arabic flat bread, which, thus, became important for this study. Scanning Electron Micrographs (SEM) taken on Arabic bread, depicted both intact small and the large starch granules on the outer crust area. This was mainly due to the rapid loss of moisture from the Arabic bread surface during intense baking operation leaving less moisture for gelatinization to take place. With psyllium added to WWF at 0, 3, and 5 % level, the peak time was increased from 3 to 4.5 min. The ascending and descending angle values were more or less identical in all the samples except with wheat germ addition, whereas much lower values (51 to 58°) for these parameters were observed, indicating a faster rate of dough breakdown. With psyllium, fine- and coarse bran addition to WWF, a corresponding increase in peak time was observed. Ascending and descending angles showed similar trends to that of the WWF and psyllium combinations. Use of falling number apparatus is an indirect method of measuring the diastatic enzyme activity in cereal flours. WGF showed lower falling-number values (502 s) than the WWF (607 s). Addition of fine bran to WWF lowered the falling number (607 to 563 s) whereas with coarse wheat bran and germ, these values were increased.

Tryptamine, a Microbial Metabolite in Fermented Rice Bran Suppressed Lipopolysaccharide-Induced Inflammation in a Murine Macrophage Model.

Fermentation is thought to alter the composition and bioavailability of bioactive compounds in rice bran. However, how this process affects the anti-inflammatory effects of rice bran and the bioactive compounds that might participate in this function is yet to be elucidated. This study aimed to isolate bioactive compounds in fermented rice bran that play a key role in its anti-inflammatory function. The fermented rice bran was fractionated using a succession of solvent and solid-phase extractions. The fermented rice bran fractions were then applied to lipopolysaccharide (LPS)-activated murine macrophages to evaluate their anti-inflammatory activity. The hot water fractions (FRBA), 50% ethanol fractions (FRBB), and n-hexane fractions (FRBC) were all shown to be able to suppress the pro-inflammatory cytokine expression from LPS-stimulated RAW 264.7 cells. Subsequent fractions from the hot water fraction (FRBF and FRBE) were also able to reduce the inflammatory response of these cells to LPS. Further investigation revealed that tryptamine, a bacterial metabolite of tryptophan, was abundantly present in these extracts. These results indicate that tryptamine may play an important role in the anti-inflammatory effects of fermented rice bran. Furthermore, the anti-inflammatory effects of FRBE and tryptamine may depend on the activity of the aryl hydrocarbon receptor.

The Antioxidant Potential of Grains in Selected Cereals Grown in an Organic and Conventional System

The paper presents the effect of conventional (use of NPK mineral fertilizers and pesticides) and organic (no use of agrochemicals) farming systems on selected parameters of antioxidant properties of winter wheat, spring barley and oat grain. The research was carried out during the period 2017–2019 at the Czesławice Experimental Farm (central Lublin region, Poland) on loess soil (second quality class). The aim of the research was to evaluate the functional (antioxidant) properties of winter wheat, spring barley and oat grain in whole grain and its milling fractions (dehulled grain, flour and bran). The reduction potential (Fe+3 → Fe+2 ), the ability to eliminate the free DPPH• radical and the total antioxidant potential in the β-carotene/linoleic acid system were determined. Polyphenol content was also determined using Folin–Ciocalteau reagent. The organic system did not significantly increase the antioxidant properties of cereal grains compared to the conventional system. Under organic farming conditions, oat grain was characterised only by the most favourable antioxidant properties. A highly statistically significant correlation was found between total polyphenol content and DPPH• free radical quenching capacity, especially for oat and barley in the organic system. The closest correlations were for the fractions of bran and whole grain. Dehulling of grain, with the exception of oat grain, irrespective of the farming system, resulted in a significant deterioration of the antioxidant potential of grain extracts. In summary, the study showed that the bran obtained from oat grown under an organic system had the strongest antioxidant activity.

RNA-seq reveals transcriptional differences in anthocyanin and vitamin biosynthetic pathways between black and white rice

Anthocyanins and vitamins in black rice are the micronutrients vital to human health, both of which predominantly accumulate in the bran fraction. Some studies have demonstrated that black rice contains more vitamins compared with common white rice, indicating potential association between anthocyanin and vitamin accumulation. In this study, transcriptomes of pericarps collected from 27 black rice accessions and 49 white rice accessions at 10 days after flowering (DAF) were sequenced and analyzed. We identified 830 differentially expressed genes (DEGs) including 58 transcription factors (TFs) between black and white rice. Among 58 differentially expressed transcription factors, OsTTG1 was confirmed to be the one and only WD40 repeat protein regulating anthocyanin biosynthesis in the pericarp. Moreover, we identified 53 differentially expressed synthetic-related genes among 42 main synthesis enzymes in the biosynthesis pathway of seven vitamins including β-carotene, vitamin B1, vitamin B2, vitamin B5, vitamin B7, vitamin B9 and vitamin E. Collectively, our results provide valuable insights into the molecular mechanism of biosynthesis of anthocyanins and vitamins and the potential effect of anthocyanin biosynthesis on vitamin biosynthesis in black rice.

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.