Purple, high β-glucan, hulless barley as valuable ingredient for functional food

Metabolic profiling of (poly)phenolic compounds in mouse urine following consumption of hull-less and purple-grain barley

The present study attempted for the first time to investigate the metabolic fate of (poly)phenolic compounds provided by a hull-less and purple grain barley genotype biofortified in anthocyanins. Balb/c mice were supplemented either with standard purified diet (SD) or whole-grain barley supplemented diet (WGB) for six weeks. Subsequently, (poly)phenolic metabolites were determined in urine samples by UPLC-MS/MS, and the principal metabolic pathways were elucidated. Thirty-nine (poly)phenolics compounds were identified in WGB which were distributed between the free (58%) and bound (42%) fractions, encompassing anthocyanins, phenolic acids, flavan-3-ols and flavones. Upon WGB intake, forty-two (poly)phenolic metabolites were identified, predominantly comprising phase-II sulphate, glucuronide, and/or methylated conjugates, along with colonic catabolites. Noteworthy metabolites included peonidin-3-O-glucuronide, peonidin-3-O-6''-O-malonylglucoside, and peonidin-3-O-glucoside among anthocyanins; hydroxyphenylpropanoic acid-O-sulphate among phenolic acids; and 5-(3',4'-dihydroxyphenyl)-γ-valerolactone-O-sulphate among flavan-3-ols. Metabolites like phenylpropionic, phenylacetic, hydroxybenzoic, and hippuric acids were found in both WGB and SD groups, with higher levels after barley consumption, indicating both endogenous and polyphenolic metabolism origins. Overall, this study offers valuable insights into the metabolism of (poly)phenols in purple barley, setting the stage for future investigations into the health benefits linked to the consumption of purple grain barley.

Unveiling the mysteries of HvANS: a study on anthocyanin biosynthesis in qingke (hordeum vulgare L. var. Nudum hook. f.) seeds

BACKGROUND

Based on our previous research, a full-length cDNA sequence of HvANS gene was isolated from purple and white Qingke. The open reading frame (ORF) in the purple variety Nierumuzha was 1320 base pairs (bp), encoding 439 amino acids, while the ORF in the white variety Kunlun 10 was 1197 bp, encoding 398 amino acids. A nonsynonymous mutation was found at the position of 1195 bp (T/C) in the coding sequence (CDS) of the HvANS gene. We carried out a series of studies to further clarify the relationship between the HvANS gene and anthocyanin synthesis in Qingke.

RESULTS

The conservative structural domain prediction results showed that the encoded protein belonged to the PLN03178 superfamily. Multiple comparisons showed that this protein had the highest homology with Hordeum vulgare, at 88.61%. The approximately 2000 bp promoter sequence of the HvANS gene was identical in both varieties. The real-time fluorescence PCR (qRT-PCR) results revealed that HvANS expression was either absent or very low in the roots, stems, leaves, and awns of Nierumuzha. In contrast, the HvANS expression was high in the seed coats and seeds of Nierumuzha. Likewise, in Kunlun 10, HvANS expression was either absent or very low, indicating a tissue-specific and variety-specific pattern for HvANS expression. The subcellular localization results indicated that HvANS was in the cell membrane. Metabolomic results indicated that the HvANS gene is closely related to the synthesis of three anthocyanin substances (Idaein chloride, Kinetin 9-riboside, and Cyanidin O-syringic acid). Yeast single hybridization experiments showed that the HvANS promoter interacted with HvANT1, which is the key anthocyanin regulatory protein. In a yeast two-hybrid experiment, we obtained two significantly different proteins (ZWY2020 and POMGNT2-like) and verified the results by qRT-PCR.

CONCLUSIONS

These results provide a basis for further studies on the regulatory mechanism of HvANS in the synthesis of anthocyanins in Qingke purple grains.

Unlocking Phenolic Potential: Determining the Optimal Grain Development Stage in Hull-Less Barley Genotypes with Varying Grain Color

Barley is rich in phenolic compounds, providing health benefits and making it a valuable addition to a balanced diet. However, most studies focus on these compounds at barley's final maturity, neglecting their synthesis during grain development and its impact on barley quality for food applications. This study investigates phenolic profiles during grain development in four hull-less barley genotypes with different grain colors, specifically bred for food applications. The objectives were to determine the phenolic profile and identify the optimal maturity stage for maximum phenolic content and antioxidant capacity. Using UPLC-MS/MS and in vitro antioxidant capacity assays, results show that total phenolic compounds decrease as grain matures due to increased synthesis of reserve components. Flavan-3-ols, phenolic acids, and flavone glycosides peaked at immature stages, while anthocyanins peaked at physiological maturity. The harvest stage had the lowest phenolic content, with a gradient from black to yellow, purple, and blue genotypes. Antioxidant capacity fluctuated during maturation, correlating positively with phenolic compounds, specially bound phenolic acids and anthocyanins. These findings suggest that early harvesting of immature grain can help retain bioactive compounds, promoting the use of immature barley grains in foods. To support this market, incentives should offset costs associated with decreased grain weight.

Structural and rheological characterization of water-soluble and alkaline-soluble fibers from hulless barley

BACKGROUND

Highland hulless barley has garnered attention as a promising economic product and a potential healthy food ingredient. The present study aimed to comprehensively investigate the molecular structure of extractable fibers obtained from a specific highland hulless barley. Water-soluble fiber (WSF) and alkaline-soluble fiber (ASF) were extracted using enzymatic digestion and an alkaline method, respectively. The purified fibers underwent a thorough investigation for their structural characterization.

RESULTS

The monosaccharide composition revealed that WSF primarily consisted of glucose (91.7%), whereas ASF was composed of arabinose (54.5%) and xylose (45.5%), indicating the presence of an arabinoxylan molecule with an A/X ratio of 1.2. The refined structural information was further confirmed through methylation, 1 H NMR and Fourier-transform infrared spectroscopy analyses. WSF fiber exclusively exhibited α-anomeric patterns, suggesting it was an α-glucan. It has a low molecular weight of 5 kDa, as determined by gel permeation chromatography. Conversely, ASF was identified as a heavily branched arabinoxylan with 41.55% of '→2,3,4)-Xylp-(1→' linkages. ASF and WSF exhibited notable differences in their morphology, water absorption capabilities and rheological properties.

CONCLUSION

Based on these findings, molecular models of WSF and ASF were proposed. The deep characterization of these fiber structures provides valuable insights into their physicochemical and functional properties, thereby unlocking their potential applications in the food industry. © 2023 Society of Chemical Industry.

The Quality Evaluation of Highland Barley and Its Suitability for Chinese Traditional Tsampa Processing

The physicochemical traits of highland barley prominently affect the quality of Tsampa. To find out the relevance between the physicochemical properties of raw material and the texture parameters of processed products, twenty-five physicochemical traits and ten quality parameters for seventy-six varieties of highland barley were measured and analyzed. The results showed that there was a significant difference between the physicochemical indexes for highland barleys of various colors. The dark highland barley generally has more fat, protein, total dietary fiber, phenolic, Mg, K, Ca, and Zn and less amylose, Fe, Cu, and Mo than light colored barley. Then, these highland barleys were made into Tsampa. A comprehensive quality evaluation model based on the color and texture parameters of Tsampa was established through principal component analysis. Then, cluster analysis was used to classify the tested samples into three edible quality grades predicated on the above evaluation model. At last, the regression analysis was applied to establish a Tsampa quality predictive model according to the physicochemical traits of the raw material. The results showed that amylose, protein, β-Glucan, and a* and b* could be used to predict the comprehensive quality of Tsampa. The predicted results indicated that 11 of 14 validated samples were consistent with the actual quality, and the accuracy was above 78.57%. Our study built the approach of the appropriate processing varieties evaluation. It may provide reference for processing specific highland barley.

Toward a comprehensive understanding of various milling methods on the physicochemical properties of highland barley flours and eating quality of corresponding sugar-free cookies

Highland barley (HB) was subjected to dry-, semidry-, wet-milling methods and assessed for flour physicochemical properties and eating quality of corresponding sugar-free cookies. Results showed that there were significant differences between different milled flours in damaged starch content, particle size, hydration, pasting properties, and color. High a* values and poor hydration/pasting properties of wet-milled flours were associated with its smallest particle size and lowest content of damaged starch (25.3%), β-glucan (1.87%), and dietary fiber (10.87%), resulting in dark brown color, slightly high spread ratio, low hardness, and fast digestibility of the corresponding cookies. Conversely, the low digestibility of the cookies (predicted glycemic index 58.85) prepared from dry-milled flours was attributed to the higher content of dietary fiber, β-glucan and V-type starch-lipid complex, which would affect enzyme accessibility and may be beneficial for making HB sugar-free cookies. This study is expected to promote the development of HB functional foods.

Naked barley: taxonomy, breeding, and prospects of utilization

This review surveys the current state of taxonomy, origin, and utilization prospects for naked barley. The cultivated barley Hordeum vulgare L. incorporates the covered and naked barley groups. Naked barleys are divided into six-row naked barley (convar. сoeleste (L.) A. Trof.) and two-row naked barley (convar. nudum (L.) A. Trof.). The groups include botanical varieties differing in the structural features of spikes, awns, floret and spikelet glumes, and the color of kernels. The centers of morphogenesis for naked barley are scrutinized employing archeological and paleoethnobotanical data, and the diversity of its forms. Hypotheses on the centers of its origin are discussed using DNA marker data. The main areas of its cultivation are shown, along with possible reasons for such a predominating or exclusive distribution of naked barley in highland areas. Inheritance of nakedness and mechanisms of its manifestation are considered in the context of new data in genetics. The biochemical composition of barley grain in protein, some essential and nonessential amino acids, β-glucans, vitamins, and antioxidants is described. Naked barley is shown to be a valuable source of unique combinations of soluble and insoluble dietary fibers and polysaccharides. The parameters limiting wider distribution of naked barley over the world are emphasized, and breeding efforts that could mitigate them are proposed. Pathogen-resistant naked barley accessions are identified to serve as promising sources for increasing grain yield and quality. Main stages and trends of naked barley breeding are considered and the importance of the VIR global germplasm collection as the richest repository of genetic material for the development of breeding is shown.

Does Plant Breeding for Antioxidant-Rich Foods Have an Impact on Human Health?

Given the general beneficial effects of antioxidants-rich foods on human health and disease prevention, there is a continuous interest in plant secondary metabolites conferring attractive colors to fruits and grains and responsible, together with others, for nutraceutical properties. Cereals and Solanaceae are important components of the human diet, thus, they are the main targets for functional food development by exploitation of genetic resources and metabolic engineering. In this review, we focus on the impact of antioxidants-rich cereal and Solanaceae derived foods on human health by analyzing natural biodiversity and biotechnological strategies aiming at increasing the antioxidant level of grains and fruits, the impact of agronomic practices and food processing on antioxidant properties combined with a focus on the current state of pre-clinical and clinical studies. Despite the strong evidence in in vitro and animal studies supporting the beneficial effects of antioxidants-rich diets in preventing diseases, clinical studies are still not sufficient to prove the impact of antioxidant rich cereal and Solanaceae derived foods on human

Effect of Highland Barley on Rheological Properties, Textural Properties and Starch Digestibility of Chinese Steamed Bread

Highland barley has a different composition and structure to other crops. It has higher contents of total polyphenol (TPC), total flavonoid (TFC) and β-glucan, which can be supplemented to improve the nutrition of wheat-flour-based food. In this study, the flours of three different grain-colored highland barley varieties Beiqing 6 (BQ), Dulihuang (DLH), and Heilaoya (HLY), were added to Jimai60 (JM, a wheat variety with medium gluten) wheat flour at different substitution levels to investigate their effects on the unextractable polymeric protein (UPP) content, micro-structure, rheological properties and mixing properties of dough, and the color, texture, flavor, and in vitro digestion of Chinese steam bread (CSB). The results showed that the moderate substitution of highland barley (20%) increased the UPP%, optimized the micro-structure of gluten, and improved its rheological properties by increasing dough viscoelasticity. The CSBs made from the composite flours exhibited a similar specific volume, cohesiveness, springiness and resilience to wheat CSB, while the firmness of composite CSBs (particularly JM-HLY-20) was delayed during storage. Importantly, the addition of highland barley increased the contents of TPC, TFC and β-glucan, but decreased the in vitro starch digestibility of CSBs. A sensory evaluation showed that JM-HLY CSB was the most preferable. Taken together, highland barley can be used as a fine supplement to food products, with health-promoting properties.

Color, Starch Digestibility, and In Vitro Fermentation of Roasted Highland Barley Flour with Different Fractions

Highland barley (HB) is commonly milled into flour for direct consumption or further processed with other food formulations. Nevertheless, the association between milling and HB flour properties remains lacking. This work studied the effect of particle sizes (coarse, 250–500 μm; medium, 150–250 μm; fine, <150 μm) on physicochemical and nutritional properties of raw and sand-roasted HB flour. Gelatinization enthalpy decreased with increasing particle sizes of raw HB flour, while no endothermic transitions were observed in sand-roasted flour. Sand roasting destroyed starch granules and decreased short-range molecular order. Starch digestibility increased while total short-chain fatty acids (SCFAs) production decreased with decreasing particle sizes in all samples. The relative crystallinity of sand-roasted HB flour decreased by 80–88% compared with raw samples. Sand roasting raised in vitro starch digestibility, while total SCFAs during in vitro fecal fermentation decreased. Sand-roasted HB flour with particle sizes <150 μm had the highest starch digestibility (94.0%) but the lowest production of total SCFAs (1.89–2.24 mM). Pearson’s correlation analysis confirmed the relationship between the nutritional qualities of HB flour and milling.

Comparison of distribution and physicochemical properties of β-glucan extracted from different fractions of highland barley grains

Highland barley grains were roller-milled to produce five different fractions (B-1, B-2, B-3, B-4, and B-5). The distribution and physicochemical properties of β-glucans from five roller-milled fractions were investigated. The B-4 fraction contained the highest concentration of β-glucan (4.40%), and the outermost bran (B-1) had the lowest β-glucan content (1.01%). Besides, β-glucans from inner core B-5 (BG-5) had higher M_w (6.482 × 10⁵ g/mol), whereas β-glucans from outer bran B-1 (BG-1) showed lower M_w (5.859 × 10⁴ g/mol) than those from other fractions. Accordingly, the viscosity of BG-5 was highest (0.038-0.365 Pa·s), and the water solubility index of BG-1 was highest (50.43-90.71%). BG-5 showed stronger foam stability and emulsifying properties but weaker foaming capability, while BG-1 exhibited stronger foaming capability. The foaming capability and emulsifying properties of β-glucan samples were better under the neutral condition (pH = 7). The foam capabilities of all β-glucan samples displayed higher values at 65 °C, and emulsifying properties exhibited higher values at 45 °C. This study is expected to promote the application of highland barley β-glucans in food industry.

Bioactive Compounds and Antioxidant Capacity in Pearling Fractions of Hulled, Partially Hull-Less and Hull-Less Food Barley Genotypes

Three food barley genotypes differing in the presence or absence of husks were sequentially pearled and their fractions analyzed for ash, proteins, bioactive compounds and antioxidant capacity in order to identify potential functional food ingredients. Husks were high in ash, arabinoxylans, procyanidin B3, prodelphinidin B4 and p-coumaric, ferulic and diferulic bound acids, resulting in a high antioxidant capacity. The outermost layers provided a similar content of those bioactive compounds and antioxidant capacity that were high in husks, and also an elevated content of tocols, representing the most valuable source of bioactive compounds. Intermediate layers provided high protein content, β-glucans, tocopherols and such phenolic compounds as catechins and bound hydroxybenzoic acid. The endosperm had very high β-glucan content and relative high levels of catechins and hydroxybenzoic acid. Based on the spatial distribution of the bioactive compounds, the outermost 30% pearling fractions seem the best option to exploit the antioxidant capacity of barley to the full, whereas pearled grains supply β-glucans enriched flours. Current regulations require elimination of inedible husks from human foods. However, due to their high content in bioactive compounds and antioxidant capacity, they should be considered as a valuable material, at least for animal feeds.

Effect of thermal treatment on the physicochemical, ultrastructural and nutritional characteristics of whole grain highland barley

Highland barley (HB) was subjected to three thermal treatments (heat fluidization, microwave, and baking) and assessed for physicochemical, ultrastructural and nutritional properties. After thermal treatments, the hardness, bulk density, thousand kernel weight, length/breadth ratio, and color difference decreased significantly, while puffing index increased. Meanwhile, the formation of fissure was observed in the appearance. Microstructure images illustrated that numerous micropores were evenly distributed in the endosperm structure, and aleurone layer cells were deformed by compression. Furthermore, a dramatically disruption of endosperm cell walls and slightly deformation of outer layers were observed by confocal laser scanning microscopy. Moreover, a notably decrease in total phenolics (14.02%-36.91%), total flavonoids (25.28%-44.94%), and bound phenolics (8.99%-27.53%) was detected, while free phenolics (8.81%-43.40%), β-glucan extractability (4.71%-43.66%), antioxidant activity (71.87%-349.77%), and reducing power (3.05%-56.13%) increased significantly. Greatest increase in nutritional values was caused by heat fluidization, which possessed the potential for development of ready-to-eat functional foods.