Phenolics levels in different parts of common buckwheat (Fagopyrum esculentum) achenes

Unveiling the differences between vitexin and isovitexin: From the perspective of sources, green advanced extraction technologies, biological activities, and safety

Vitexin and isovitexin, as the two of representative flavonoid C-glycosides, are naturally occurring bioactive compounds predominantly found in food plants. Their multiple pharmacological activities have generated a lot of interest in their application in disease management. However, as isomers, vitexin and isovitexin show differences between them in various aspects. To achieve their personalized application in precision nutrition, further research is needed to reveal their differences. Based on the various sources and distribution of vitexin and isovitexin, the advantages and limitations of various green advanced extraction technologies are discussed to improve their purity and activity. Furthermore, vitexin and isovitexin exhibit shared and diverse health benefits from the perspective of in vitro and in vivo research reports. This review contributes to a better understanding of the sustainable production of natural vitexin and isovitexin based on their differences, thus promoting the personalized application of them in the functional foods or pharmaceutical industries.

The Diversity of Morphological Traits and Seed Metabolomic Composition in Buckwheat Genetic Resources

This study examines the impact of environmental conditions on the growth, yield, and biochemical composition of common buckwheat (Fagopyrum esculentum Moench.) across two locations in Central Europe over three consecutive growing seasons (2019-2021). Significant variations in meteorological conditions, including temperature fluctuations and rainfall, were observed between two locations: Austria (AT) and the Czech Republic (CZ). The study highlights the role of these environmental factors in influencing morphological traits such as plant height, leaf dimensions, and 1000-seed weight (TSW), as well as nutritional and bioactive compound content. Buckwheat plants in Austria generally exhibited higher mean values for plant height and TSW compared to the Czech Republic, with significant variability observed across varieties and years. In terms of nutritional quality, crude protein content ranged between 12.56 and 14.71% dw, with the highest protein levels linked to cooler, low-rainfall conditions. The study also investigated phenolic compounds, particularly rutin, which showed a significant increase in content in 2021, likely due to extreme weather conditions. Varieties such as Sweden-1, Tempest, and Zamira exhibited stable, high rutin levels across all years. Overall, this research highlights the complexity of environmental influences on the agronomic and nutritional traits of buckwheat and provides valuable insights for future breeding programs aimed at improving yield and nutritional value under changing climatic conditions.

Inhibition mechanism of buckwheat hulls polyphenols on α-amylase and α-glucosidase using kinetics, spectroscopics and molecular docking approaches

The work investigated the activity inhibition of phenolic compounds in buckwheat (Fagopyrum esculentum Moench) hulls (BH) on α-amylase and α-glucosidase, and clarified their possible mechanisms based on kinetics, spectroscopics and molecular docking analysis. The total polyphenols (BHP) from BH using an ultrasound-assisted alcohol extraction method was 210.50 mg GAE/g DW. The study identified a total of 33 polyphenolic compounds in the extracts of BH using UPLC-Q-Exactive Orbitrap/MS, revealing that sixteen of these were novel polyphenolic substances not previously documented in this plant. BHP demonstrated significant inhibitory effects on both α-amylase and α-glucosidase enzymes, with IC50 values recorded at 27.16 μg/mL and 7.00 μg/mL, respectively, suggesting noncompetitive and mixed-type inhibition mechanisms. The fluorescence intensity of the enzymes was effectively quenched by BHP through a combination of dynamic and static quenching mechanisms, driven predominantly by hydrophobic interactions. BHP's interaction with the enzymes resulted in conformational changes that reduced their enzymatic activities. Molecular docking further revealed that six polyphenolic components of BHP had a strong affinity for binding with the active sites nestled in the enzymes' hydrophobic cavities, inhibiting their activity and potentially contributing to a reduction in blood glucose levels. The results could provide perspective for using BHP in the functional components of sugar-controlling foods.

Contemporary Speculations and Insightful Thoughts on Buckwheat-A Functional Pseudocereal as a Smart Biologically Active Supplement

Today, food scientists are interested in more rational use of crops that possess desirable nutritional properties, and buckwheat is one of the functional pseudocereals that represents a rich source of bioactive compounds (BACs) and nutrients, phytochemicals, antimicrobial (AM) agents and antioxidants (AOs), which can be effectively applied in the prevention of malnutrition and celiac disease and treatment of various important health problems. There is ample evidence of the high potential of buckwheat consumption in various forms (food, dietary supplements, home remedies or alone, or in synergy with pharmaceutical drugs) with concrete benefits for human health. Contamination as well as other side-effects of all the aforementioned forms for application in different ways in humans must be seriously considered. This review paper presents an overview of the most important recent research related to buckwheat bioactive compounds (BACs), highlighting their various functions and proven positive effects on human health.

A decade of advances in the study of buckwheat for organic farming and agroecology (2013-2023)

During the last decade, research has shown the environment and human health benefits of growing buckwheat (Fagopyrum spp.). This comprehensive review aims to summarize the major advancements made in the study of buckwheat from 2013 to 2023, focusing on its agronomic characteristics, nutritional value, and potential applications in sustainable agriculture. The review examines the diverse applications of buckwheat in organic and agroecological farming systems, and discusses the ability of buckwheat to control weeds through allelopathy, competition, and other sustainable farming methods, such as crop rotation, intercropping and green manure, while improving soil health and biodiversity. The review also explores the nutritional value of buckwheat. It delves into the composition of buckwheat grains, emphasizing their high protein content, and the presence of essential amino acids and valuable micronutrients, which is linked to health benefits such as lowering cholesterol levels, controlling diabetes and acting against different types of cancer, among others. Finally, the review concludes by highlighting the gaps in current knowledge, and proposing future research directions to further optimize buckwheat production in organic or agroecological farming systems. It emphasizes the need for interdisciplinary collaboration, and the integration of traditional knowledge with modern scientific approaches to unlock the full potential of buckwheat as a sustainable crop.

Valorization of wastes and by-products of nuts, seeds, cereals and legumes processing

Wastes and by-products of nuts, seeds, cereals and legumes carry a unique potential for valorization into value-added ingredients due to their protein, dietary fiber, antioxidant, vitamin and mineral contents. The most crucial factor in the recovery of value-added ingredients and bioactives from the wastes and by-products is the utilization of the most efficient extraction technique. This work is an overview of the classification of wastes and by-products of nuts, seeds, cereals and legumes processing, the methods used in the extraction of valuable compounds such as proteins, dietary fibers, phenolics, flavonoids and other bioactives. This chapter provides insights on the promising applications of extracted ingredients in various end products. A special emphasis is given to the challenges and improvement methods for extraction of value-added compounds from wastes and by-products of nuts, seeds, cereals and legumes processing.

Buckwheat Hull-Enriched Pasta: Physicochemical and Sensory Properties

This work aimed to evaluate the effect of partial replacement of semolina with 0, 1, 5, 10, 15, and 20% of ground buckwheat hull (BH) on the chemical composition, antioxidant properties, color, cooking characteristics, and sensory properties of wheat pasta. Pasta samples were prepared by dough lamination (tagliatelle shape) and dried at 55 °C until the moisture content was 11–12% (wet basis). Analyses of samples showed that the addition of BH caused an increase in fiber content in pasta from 4.31% (control pasta) to 14.15% (pasta with 20% of BH). Moreover, the brightness and yellowness of BH-enriched products were significantly decreased compared to the control sample, and the total color difference ranged from 23.84 (pasta with 1% of BH) to 32.56 (pasta with 15% BH). In addition, a decrease in optimal cooking time, as well as an increased weight index and cooking loss, was observed in BH-enriched pasta samples. Furthermore, BH-enriched cooked pasta had significantly higher total phenolic content and antioxidant activity but an unpleasant smell and taste, especially if the level of BH was higher than 10%.

Phenolics in buckwheat hull extracts and their antioxidant activities on bulk oil and emulsions

Buckwheat hulls are discarded as waste, although they have more phenolic compounds than buckwheat groats. The antioxidant activities of buckwheat hull extracts prepared with water, 50% ethanol, and 100% ethanol were investigated in bulk oil, oil-in-water (O/W), and water-in-oil (W/O) emulsions. The relationship between the phenolic compositions of the extracts and their antioxidant activities in the three different lipid systems was also evaluated. Fifty percent ethanol extract had the highest total phenolic content (327 mg gallic acid equivalent [GAE]/g extract) followed by water and 100% ethanol extracts (211 and 163 mg GAE/g extract, respectively). The total oxidation rate (k) was not significantly different among the bulk oils added with the buckwheat hull extracts. However, in the O/W emulsion, the k was more reduced by the 50% and 100% ethanol extracts than by the water extract at the concentration of 100 µg GAE/g (2.9, 2.8, and 3.7 Totox/day, respectively). The k of the W/O emulsion was more reduced by the 100% ethanol extract than by the water and 50% ethanol extract at the concentration of 100 µg GAE/g (3.8, 4.7, and 4.5 Totox/day, respectively). Multivariate statistical analysis revealed that the contents of phenolic acids and their derivatives were the highest in the water extract among the extracts, while the contents of flavonoid glycosides and methylated polyphenols were the highest in the 50% and 100% ethanol extracts, respectively. The results suggest that flavonoid glycosides and methylated polyphenols could be potential candidates for retarding the oxidation of the emulsion system. PRACTICAL APPLICATION: Buckwheat hull extracts could retard lipid oxidation. Flavonoid glycosides and methylated polyphenols in buckwheat hull extracts may have an antioxidative effect on lipids. Thus, buckwheat hulls could be used as an antioxidant in lipid systems, as flavonoid glycosides and methylated polyphenols are properly extracted from buckwheat hulls.

Impact of Rutin and Other Phenolic Substances on the Digestibility of Buckwheat Grain Metabolites

Tartary buckwheat (Fagopyrum tataricum Gaertn.) is grown in eastern and central Asia (the Himalayan regions of China, Nepal, Bhutan and India) and in central and eastern Europe (Luxemburg, Germany, Slovenia and Bosnia and Herzegovina). It is known for its high concentration of rutin and other phenolic metabolites. Besides the grain, the other aboveground parts of Tartary buckwheat contain rutin as well. After the mixing of the milled buckwheat products with water, the flavonoid quercetin is obtained in the flour-water mixture, a result of rutin degradation by rutinosidase. Heating by hot water or steam inactivates the rutin-degrading enzymes in buckwheat flour and dough. The low buckwheat protein digestibility is due to the high content of phenolic substances. Phenolic compounds have low absorption after food intake, so, after ingestion, they remain for some time in the gastrointestinal tract. They can act in an inhibitory manner on enzymes, degrading proteins and other food constituents. In common and Tartary buckwheat, the rutin and quercetin complexation with protein and starch molecules has an impact on the in vitro digestibility and the appearance of resistant starch and slowly digestible proteins. Slowly digestible starch and proteins are important for the functional and health-promoting properties of buckwheat products.

Breeding Buckwheat for Nutritional Quality in the Czech Republic

Buckwheat is a nutritionally valuable crop, an alternative to common cereals also usable in gluten-free diets. The selection of buckwheat genotypes suitable for further breeding requires the characterization and evaluation of genetic resources. The main objective of this work was to evaluate selected phenotypic and morphological traits using international buckwheat descriptors, including total phenolic content and antioxidant activity, on a unique set of 136 common buckwheat accessions grown in 2019-2020 under Czech Republic conditions. In addition, UHPLC-ESI- MS/MS was used to analyze a wide spectrum of 20 phenolic compounds in buckwheat seeds, including four flavanols, three phenolic acids, seven flavonols, four flavones, and two flavanones. Significant differences among years and genotypes were observed for morphological traits (plant height and 1000-seed weight) and antioxidant activity, as well as levels of observed chemical compounds. Antioxidant activity, crude protein content, plant height and rutin content were characterized by higher mean values in 2020 than in 2019 and vice versa for total polyphenol content and 1000-seed weight. Crude protein content was the most stable across years, while total polyphenol content and rutin content varied greatly from year to year. The most abundant phenolic compounds were rutin, hyperoside, epicatechin, catechin, vitexin, isovitexin, orientin and isoorientin. Protein content was negatively correlated with plant height, catechin and epicatechin content. On the other hand, AA and TPC were positively correlated with rutin, hyperoside and chlorogenic acid. Five accessions showed high stability of the evaluated traits under changing conditions within both years of observation. These materials can be used in breeding programmes aimed at improving buckwheat genotypes with emphasis on quality traits.

Effect of Vermicompost Application on Mineral Nutrient Composition of Grains of Buckwheat (Fagopyrum esculentum M.)

Poor soil organic content is a major cause of declining crop productivity in developing countries. Less precipitation and high temperatures oxidize organic matter in the soils of semi-arid regions. Such a deficiency in the organic matter of the soils decreases the bioavailability of many nutrients. Organic amendments like vermicompost (VM) have the potential to overcome this problem, while decreasing the dependency on inorganic fertilizers. Thus, the aim of our study was to explore the best application rate of VM for the improvement of nutrient contents in buckwheat. We used two buckwheat cultivars i.e., Aktaş and Güneş were sown under variable rates of soil-applied VM (0, 0.75, 1.50, 2.25 and 3.00 t ha−1) in semi-arid highland conditions. The results demonstrated that the nutritional quality parameters were improved when VM was applied at the rate of 2.25 t ha−1. In addition, VM at 2.25 t ha−1 resulted in an improvement of the N and P contents of the grains. The P contents in the grains of the Güneş variety was higher (0.26%) than the Aktaş variety (0.24%). A significant improvement in Fe (%), Cu (%), Zn (%) and Mn contents (%) in the grains of buckwheat validated the efficacious functioning of 2.25 t ha−1 of VM. The Zn content of the grains was higher in the Güneş variety (34.06%) than the Aktaş variety (31.96%). However, no significant change in K, Ca and Mg was noted at any level of VM in both Aktaş and Güneş. It is concluded that a 2.25 t ha−1 VM application in the buckwheat crop under zero conventional fertilizer was the best level to boost the nutritional quality of the grains.

Germinated Buckwheat: Effects of Dehulling on Phenolics Profile and Antioxidant Activity of Buckwheat Seeds

The aim was to investigate the effects of the cold dehulling of buckwheat seeds on their germination, total phenolic content (TPC), antioxidant activity (AA) and phenolics composition. Cold dehulling had no negative effects on germination rate and resulted in faster rootlet growth compared to hulled seeds. Although the dehulling of the seeds significantly decreased TPC and AA, the germination of dehulled seeds resulted in 1.8-fold and 1.9-fold higher TPC and AA compared to hulled seeds. Liquid chromatography coupled to mass spectrometry identified several phenolic compounds in free and bound forms. Rutin was the major compound in hulled seeds (98 µg/g dry weight), orientin and vitexin in 96-h germinated dehulled seeds (2205, 1869 µg/g dry weight, respectively). During germination, the increases in the major phenolic compounds were around two orders of magnitude, which were greater than the increases for TPC and AA. As well as orientin and vitexin, high levels of other phenolic compounds were detected for dehulled germinated seeds (e.g., isoorientin, rutin; 1402, 967 µg/g dry weight, respectively). These data show that dehulled germinated seeds of buckwheat have great potential for use in functional foods as a dietary source of phenolic compounds with health benefits.

Breeding Buckwheat for Increased Levels and Improved Quality of Protein

Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) and common buckwheat (Fagopyrum esculentum Moench) are important sources of proteins with balanced amino-acid compositions, and thus of high nutritional value. The polyphenols naturally present in Tartary buckwheat and common buckwheat lower the true digestibility of the proteins. Digestion-resistant peptides are a vehicle for fecal excretion of steroids, and in this way, for bile acid elimination and reduction of cholesterol concentrations in serum. Buckwheat proteins are more effective compared to soy proteins for the prevention of gallstone formation. Tartary and common buckwheat grain that contains appropriate amounts of selenium-containing amino acids can be produced as functional food products. The protein-rich by-products of buckwheat are a good source of bioactive substances that can suppress colon carcinogenesis by reducing cell proliferation. The grain embryo is a rich source of proteins, so breeding buckwheat with larger embryos is a possible strategy to increase protein levels in Tartary and common buckwheat grain. However, chemical analysis of the grain is the most relevant criterion for assessing grain protein levels and quality.

Breeding Buckwheat for Increased Levels of Rutin, Quercetin and Other Bioactive Compounds with Potential Antiviral Effects

Common buckwheat (Fagopyrum esculentum Moench) and Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn.) are sources of many bioactive compounds, such as rutin, quercetin, emodin, fagopyrin and other (poly)phenolics. In damaged or milled grain under wet conditions, most of the rutin in common and Tartary buckwheat is degraded to quercetin by rutin-degrading enzymes (e.g., rutinosidase). From Tartary buckwheat varieties with low rutinosidase activity it is possible to prepare foods with high levels of rutin, with the preserved initial levels in the grain. The quercetin from rutin degradation in Tartary buckwheat grain is responsible in part for inhibition of α-glucosidase in the intestine, which helps to maintain normal glucose levels in the blood. Rutin and emodin have the potential for antiviral effects. Grain embryos are rich in rutin, so breeding buckwheat with the aim of producing larger embryos may be a promising strategy to increase the levels of rutin in common and Tartary buckwheat grain, and hence to improve its nutritional value.

Treasure from garden: Bioactive compounds of buckwheat

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An extensive review on diverse bioactive components of buckwheat.

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Versatile beneficial phytochemicals are abundant in buckwheat.

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Buckwheat has a wide range of pharmacological and beneficial health effects.

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Huge research scope on Fagopyrum cymosum to identify the beneficial phytochemicals.

Buckwheat is a gluten-free crop under the family Polygonaceae abundant with beneficial phytochemicals that provide significant health benefits. It is cultivated and adapted in diverse ecological zones all over the world. Recently its popularity is expanding as a nutrient-rich healthy food with low-calories. The bioactive compounds in buckwheat are flavonoids (i.e., rutin, quercetin, orientin, isoorientin, vitexin, and isovitexin), fatty acids, polysaccharides, proteins, and amino acids, iminosugars, dietary fiber, fagopyrins, resistant starch, vitamins, and minerals. Buckwheat possesses high nutritional value due to these bioactive compounds. Additionally, several essential bioactive factors that have long been gaining interest because these compounds are beneficial for healing and preventing several human diseases. The present review demonstrates an overview of the recent researches regarding buckwheat phytochemicals and particularly focusing on the distinct function of bioactive components with their health benefits.

Effect of Probiotics and Herbal Products on Intestinal Histomorphological and Immunological Development in Piglets

The aim of the study was to evaluate the effect of probiotics and herbal products on the intestinal histomorphological and immunological development in piglets. Accordingly, 2-week-old piglets were allocated in 4 groups: C (basal diet), Pro (basal diet + probiotics), Pro+B (basal diet + probiotics + buckwheat bran), and H (powder of herbs). After 6 weeks of the experiment, 4 piglets from each experimental group were randomly selected and slaughtered at a slaughterhouse. Samples of tissue and digestive content from the jejunum and colon were collected for bacteriological, histological, and immunohistochemical examination. The results showed that probiotics increased the number of Lactobacillus spp. in the small (p < 0.05) and large intestines. The intestinal histomorphology was improved (p < 0.05) in all experimental groups by an increased villus height, VH : CD ration, colon crypt depth, and number of Ki-67⁺ epithelial cells. A higher number (p < 0.05) of goblet cells and their acidification were observed in group Pro, while the density of goblet cells was decreased by the herbs. Probiotics increased (p < 0.05) the number of intraepithelial lymphocytes (IELs), density of CD3⁺ cells in Peyer's patches (PPs), and lamina propria (LP). In group H, a dual effect on the CD3⁺ cell distribution was observed. The herbs reduced (p < 0.05) the number of IELs and CD3⁺ in LP but increased the distribution of CD3⁺ cells in PPs. In the colon, herbs increased CD3⁺ cells in LP as well. It suggests that probiotics and herbs had influence on the intestinal histomorphology and the ability to modulate the mucosal immune system; however, the combination of probiotics and buckwheat bran was not so convincing, probably due to the inhibitory effect of the buckwheat bran on the probiotics used.

Breeding buckwheat for nutritional quality

Common buckwheat (Fagopyrum esculentum Moench, CB) and Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn., TB) are used in human nutrition. The idea to screen in the haploid phase for genes affecting low amylose concentration opens the possibility for the effective search of low amylose (waxy) genotypes in CB populations. Self-pollinated homozygous plants of TB might allow us to use a part of endosperm for screening of amylose content. Phenolic substances have a significant inhibitory effect on the digestion of CB and TB proteins, thus metabolites may have impact on protein digestibility. Digestion-resistant peptides are largely responsible for the bile acid elimination. Breeding to diminish polyphenols and anti-nutritional substances might have negative effects on the resistance of plants against pests, diseases and UV-radiation. Bread and pasta are popular CB and TB dishes. During dough making most of CB or TB rutin is degraded to quercetin by rutin-degrading enzymes. The new trace-rutinosidase TB variety makes possible making TB bread with considerable amount of rutin, preserving the initial rutin from flour. Breeding CB and TB for larger embryos would make it possible to increase protein, rutin, and essential minerals concentration in CB and TB grain.

Distribution of Free and Bound Phenolic Compounds in Buckwheat Milling Fractions

Buckwheat is a rich source of phenolic compounds that have shown to possess beneficial effect to reduce some diseases due to their antioxidant power. Phenolic compounds are present in the free and in the bound form to the cell wall that are concentrated mainly in the outer layer (hull and bran). Hull is removed before the milling of buckwheat to obtain flours. In order to evaluate the phenolic composition in dehulled buckwheat milling fractions, it was carried out a determination of free and bound phenolic compounds in dehulled whole buckwheat flour, light flour, bran flour, and middling flour by high-performance liquid chromatography-mass spectrometry (HPLC–MS). The most abundant free phenolic compounds were rutin and epiafzelchin–epicatechin-O-dimethylgallate, whereas the most abundant bound phenolic compounds were catechin and epicatechin in all buckwheat flours. Besides, the highest content of free phenolic compounds was obtained in bran flour (1249.49 mg/kg d.w.), whereas the greatest bound phenolic content was in middling (704.47 mg/kg d.w.) and bran flours (689.81 mg/kg d.w.). Thus, middling and bran flours are naturally enriched flours in phenolic compounds that could be used to develop functional foods.

Use of Sieving As a Valuable Technology to Produce Enriched Buckwheat Flours: A Preliminary Study

Fractionation processes based on physical separation are a good strategy to produce enriched cereal flours. Therefore, the aim of this work is to evaluate the suitability of sieving of buckwheat flours to produce protein and phenolic (especially rutin) enriched fractions. Because of that, dehulled whole buckwheat flour (GSTQ) was sieved obtaining fractions with a particle size of 215 µm, 160 µm, 85 µm, and 45 µm (GS215, GS160, GS85, and GS45). For that purpose, the determination of protein, ash, and total starch content and free and bound phenolic compounds was carried out. The highest content of total phenolic compounds was obtained in GS215 (3118.84 mg Kg-1 d.w.), followed by GS160 (2499.11 mg Kg-1 d.w.), GS85 (989.46 mg Kg-1 d.w.), GSTQ (983.15 mg Kg-1 d.w.), and GS45 (481.31 mg Kg-1 d.w.). Therefore, the phenolic content decreased with the particle size decrease from 215 µm to 45 µm. Besides, there were no significant differences between the total phenolic content in GS85 and GSTQ. The fraction with 215 µm reported the highest protein and mineral salt content and presented rutin amounts four times higher than GSTQ.