Effects of sonication on the in vitro digestibility and structural properties of buckwheat protein isolates

The present work investigated the effects of sonication at different amplitudes and durations on the in vitro digestibility of buckwheat protein isolates (BPIs). The conformation, particle size and microstructures of the BPIs were also studied to explicate the possible mechanisms of the sonication-induced changes. The results showed that sonication conditions of 20 kHz, pulsed on-time 10 s, off-time 5 s, amplitude of 60% and duration of 10 min (SA6T10) improved the digestibility of BPIs from 41.4% (control) to 58.2%. The tertiary structure analysis showed that sonication exposed the hydrophobic core buried inside the protein molecules and broke the intramolecular crosslinks, based on the increase in the surface hydrophobicity and intrinsic fluorescence and the decrease in the disulphide content. The secondary structure analysis showed that SA6T10 decreased the content of β-turn and β-sheet by 40.9% and 22.4%, respectively, and increased the content of anti-parallel β-sheet, random coil, and α-helix by 40.9%, 30.6%, and 25.5%, respectively. The particle size of the control BPIs (427.7 ± 76.7 nm) increased to 2130.8 ± 356.2 nm in the SA6T10 sonicated sample with a corresponding decrease in the polydispersity index from 0.97 ± 0.04 to 0.51 ± 0.13. Moreover, scanning electron microscopy indicated that sonication broke the macroparticles into smaller fragments and changed the surface state of the proteins. Taken together, sonication has proven to be a promising approach for improving the digestibility of buckwheat proteins, which can be explored as a source of plant-based alternative protein for food applications.

Sensitivity of yellow foxtail (Setaria glauca L.) and barnyardgrass (Echinochloa crus-galli L.) to aqueous extracts or dry biomass of cover crops

BACKGROUND

The common weeds Echinochloa crus-galli L. and Setaria glauca L. were studied for their sensitivity to aqueous extracts or dry biomass of the following cover crops (CCs): Brassicaceae (Sinapis alba, Raphanus sativus var. Oleiformis, Camellina sativa), Fagopyrum esculentum and Guizotia abyssinica.

RESULTS

Treating E. crus-galli with aqueous extracts of mixed CCs or individual brassica CC significantly reduced germination. Treating S. glauca with aqueous extracts of C. sativa or G. abyssinicia reduced germination. Aqueous extracts of all CCs significantly reduced radicle length of E. crus-galli and S. glauca, with C. sativa and mixed CCs showing the greatest effect. Aqueous extracts of nearly all CCs delayed start and middle germination of E. crus-galli and S. glauca, with S. alba and R. sativus showing the strongest effects. Aqueous extracts of Brassicaceae leaf and flower significantly reduced germination, coleoptile length, radicle length and seedling biomass of E. crus-galli and S. glauca. Brassicaceae leaves and flowers contained higher phenolics than other tissues. Adding 4 or 8% S. alba and R. sativus dry powder to soil significantly reduced growth of E. crus-galli and S. glauca; even concentrations of 1% measurably slowed growth of E. crus-galli.

CONCLUSIONS

Brassicaceae may be allelopathic to S. glauca and E. crus-galli. Aqueous extracts of leaves and flowers showed greater phytotoxic activity than other tissues and also contained more phenolics. Therefore Brassicaceae CCs may be most effective against S. glauca and E. crus-galli if incorporated into soil during their flowering stage. © 2020 Society of Chemical Industry.

Rheology and tribology properties of cereal and legume flour paste from different botanical origins

Paste made from eight types of cereal grains (low fiber containing grains [LF grains]: rice, sticky rice, black rice, and millet; and high fiber containing grains [HF grains]: wheat, buckwheat, oat, and barley), and four types of legumes (soybean, red bean, kidney bean, and mung bean), were studied in terms of particle size, rheological, and tribological properties. Sticky rice and soybean pastes showed lower yield stress, viscosity and consistency coefficient than other pastes. Most cereal pastes showed a major peak at approximately 160 µm except for oat and barley, while legume pastes showed mono modal profiles except for soybean. Tribological results showed that starch tended to develop type A friction profiles, showing a typical Stribeck curve; bran/fiber tended to develop type B profiles, showing an ascent curve with clear onset of hydrodynamic regime; protein and lipids promoted type C profiles, showing a flat plateau shaped curve. Water soluble polysaccharides in grains or legumes could improve the paste lubrication. In general, 5% of the black rice paste and sticky rice in the LF grain group, and the soybean paste in the legume group, showed a low friction coefficient (μ) in the entire entrainment speed range; barley paste and oat paste in the HF grain group showed relatively low μ at low entrainment speed (0.5 mm/s) and medium entrainment speed (5 and 10 mm/s), respectively.

The Application of Lamiaceae Lindl. Promotes Aroma Compounds Formation, Sensory Properties, and Antioxidant Activity of Oat and Buckwheat-Based Cookies

Aroma plays an important role in designing innovative functional foods. This study aimed to study the influence of incorporating herbs from the Lamiaceae family (sage, mint, rosemary, oregano, thyme) on aroma compound formation and sensory properties in oat-buckwheat products. DPPH, FRAP and PCL have been used to describe possible antioxidant activity changes and reduce power of cookies after Lamiaceae Lindl. addition. The volatiles analysis by HS-SPME-GC/MS, has shown that Lamiaceae addition significantly influences the volatiles composition (29 molecules) with a predominance of molecules with a positive sensorial impression. Cookies elaborated with herbs were characterized by a greater share of monoterpenes (e.g., limonene, eucalyptol), in the volatile profile than in control cookies. These compounds’ occurrence was closely correlated with the appearance of herbal odor and taste among sensory attributes in cookies with herbs addition. In contrast, a decrease of negative oil aroma and the bitter aftertaste was noted by a sensory panel. Moreover, in cookies of mint and rosemary, hexanal share decreased about 13 and 9.7-times, respectively. Considering all presented experiments, rosemary addition was the most effective in forming a positive aroma profile with high sensory acceptance and increased functional properties.

Buckwheat Secondary Metabolites: Potential Antifungal Agents

Research groups have put significant emphasis on the evaluation of nutritional, health-promoting, and other biological activities of secondary metabolites from buckwheat. Among these phytochemicals, phenolic and lipophilic antioxidants, particularly, phenolic acids, flavonoids, and tocopherols, have been the focus of the latest studies since antioxidant activity has recently been associated with the possibility of inhibiting fungal growth and mycotoxin biosynthesis. The mycotoxin contamination of cereal and pseudocereal grains caused primarily by Fusarium, Penicillium, and Aspergillus species poses a significant hazard to human health. Therefore, efforts to examine the involvement of plant antioxidants in the biosynthesis of mycotoxins at the transcriptional level have emerged. In addition, hydrophobic interactions of buckwheat phenolics with cell membranes could also explain their capacity to reduce fungal development. Eventually, possibilities of enhancing the biological activity of cereal and pseudocereal phytochemicals have been studied, and sourdough fermentation has been proposed as an efficient method to increase antioxidant activities. This effect could result in an increased antifungal effects of sourdough and bakery products. This review reports the main advances in research on buckwheat phenolics and other antioxidant phytochemicals, highlighting possible mechanisms of action and processes that could improve their biological activities.

Comparison of physicochemical properties of recombinant buckwheat trypsin inhibitor (rBTI) and soybean trypsin inhibitor (SBTI)

The inhibitory activities of buckwheat trypsin inhibitor (rBTI) towards trypsin were compared with soybean trypsin inhibitor (SBTI) in terms of their sensitivities to temperature, pH, salt ions and organic solvents. Both rBTI and SBTI were stable over a broad pH range of 2.0-12.0. rBTI exhibited higher thermal stability than SBTI. The inhibitory activity of rBTI was decreased by Zinc ions (Zn2+), KSCN, vitamin C and urea, while that of SBTI remained unchanged. However, H2O2, Mg2+ and Cu2+ ions had no significant effects on the inhibitory activities of rBTI and SBTI. Acetonitrile enhanced the inhibitory activity of rBTI, but had no effect on SBTI, while dimethylacetamide (DMAC) increased the inhibitory effect of both rBTI and SBTI. On the contrary, the inhibitory activities of rBTI and SBTI were reduced by isopropyl alcohol and methanol. The inhibition constants Ki of rBTI and SBTI were calculated to be 7.41 × 10-9 M and 6.52 × 10-9 M, respectively.

Ultrasound Treatment of Buckwheat Grains Impacts Important Functional Properties of Resulting Flour

The benefit of not containing the gluten complex protein also provides problems with the achievement of typical and proper texture, especially in bakery products. Ultrasound (US) treatment has been previously studied on buckwheat as assistance treatment facilitating the release of antioxidant compounds. However, there is no study regarding the changes occurring in US-treated buckwheat grains regarding the structure-creating capacity, like water absorption, gelling, and pasting. The aim of this study is to the impact of US-treatment of buckwheat grains at 1:10, 1:5, and 1:2.5 solid: liquid ratio (in water). The particle size distribution, water absorption index (WAI), water solubility index (WSI), swelling power (SP), pasting characteristics, color, soluble, insoluble and total polyphenols content (SPC, IPC, TPC) and antioxidant activity (DPPH) were assessed in resulting flours. US-treatment caused specific agglomeration, resulting in bigger particles for 1:5, and 1:2.5 ratio treated samples, while higher dilution (1:10) increased smaller particle size fractions. The WAI and SP were the highest for the1:5 solid: liquid ratio sample, and the same sample revealed the highest peak viscosity, breakdown, and setback values. The ultrasound treatment increased the WSI, which was positively correlated with insoluble polyphenols content. The soluble polyphenols content decreased, and insoluble polyphenols content increased in all ultrasound treated samples. The DPPH scavenging activity remaining in grain after US treatment was lowered compared to the control sample. The relocation of pigments resulted in a redness and yellowish increase in all treated samples, while lightness was also increased but was most pronounced for a 1:10 ratio treated sample. The results suggest that ultrasound treatment of grain can improve the essential functional properties of buckwheat flour.

Lipid-Lowering Effects and Intestinal Transport of Polyphenol Extract from Digested Buckwheat in Caco-2/HepG2 Coculture Models

Polyphenol extracts derived from gastrointestinal digestates of buckwheat (Fagopyrum Mill) were studied for their intestinal transport and lipid-lowering effects in Caco-2/HepG2 coculture models. The relative amounts of all phenolic compounds throughout the digestion and intestinal absorption process were determined by UHPLC-Q-Orbitrap mass spectrometry. The digestible and easily transported phenolic compounds in buckwheat extract were identified. Herein, four main phenolic compounds and their metabolites were found on both the apical and basolateral sides of the Caco-2 cell transwell model. The transepithelial transport rates in the Caco-2 cell monolayer were scoparone (0.97) > hydroxycinnamic acid (0.40) > rutin (0.23) > quercetin (0.20). The main metabolism of hydroxycinnamic acid, quercetin, and scoparone in transepithelial transport was found to be methylation. Furthermore, results indicated that triglyceride, low-density lipoprotein cholesterol, total cholesterol, aspartate aminotransferase, and alanine aminotransferase levels in HepG2 cells on the basolateral side of coculture models can be suppressed by 53.64, 23.44, 36.49, 27.98, and 77.42% compared to the oleic acid-induced group (p < 0.05). In addition, the mRNA expression of Fabp4 relative to the control was found to be significantly upregulated (85.82 ± 10.64 to 355.18 ± 65.83%) by the easily transported buckwheat polyphenol components in HepG2 cells (p < 0.01).

Effects of a fermented buckwheat flower and leaf extract on the blood glucose and lipid profile of type 2 diabetic db/db mice

OBJECTIVE

To determine the efficacy of a fermented buckwheat flower and leaf extract (EFBFL) for the reduction of blood glucose and lipid dysregulation in spontaneously obese type 2 diabetic db/db mice, and to explore the possible mechanisms involved.

METHODS

Forty 9-week-old male db/db mice were randomly allocated to a high-dose EFBFL group (EFBFL-H), a low-dose EFBFL group (EFBFL-L), a metformin hydrochloride positive control group (MEG), and a db/db control group (MG), and there was also a db/m negative control group (NCG) (n = 10). Oral glucose tolerance tests (OGTT) were performed after 7 weeks of treatment. At the end of 8 weeks of treatment, random blood glucose (RBG), glycosylated hemoglobin (HbAlc), fasting plasma glucose (FPG), fasting serum insulin (FINS) , triglyceride (TG), serum total cholesterol (TC), free fatty acids (FFA), high-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol (LDL-c) were measured, the homeostasis model assessment-insulin resistance (HOMA-IR) was calculated. Immunohistochemistry and western blotting measured the expression of glucose transporter4 (GLUT4) and peroxisome proliferator-activated receptor γ (PPAR-γ) by in skeletal muscle.

RESULTS

The MG mice had a significantly increased in RBG, HbAlc, the HOMA-IR level, the serum of TG, TC, LDL-c, but a decreased in glucose tolerance and the protein expression of GLUT4 and PPAR-γ compared with the NCG. Compared with the MG, EFBFL groups significantly decreased RBG, HbAlc, and the HOMA-IR level, increased glucose tolerance. Meanwhile EFBFL groups reduced the serum TG, TC, and LDL-c in a dose-dependent manner. In addition, EFBFL increased the protein expression of GLUT4 and PPAR-γ in the skeletal muscle of db/db mice. There was significant difference between the MG group and EFBFL groups.

CONCLUSION

These findings suggest that EFBFL has anti-diabetic effects in db/db mice, ameliorating glucose intolerance, lipid dysregulation, and insulin resistance.

Honey as Source of Nitrogen Compounds: Aromatic Amino Acids, Free Nucleosides and Their Derivatives

The content of selected major nitrogen compounds including nucleosides and their derivatives was evaluated in 75 samples of seven varieties of honey (heather, buckwheat, black locust, goldenrod, canola, fir, linden) by targeted ultra-high performance liquid chromatography-diode array detector - high-resolution quadrupole time-of-flight mass spectrometry (UHPLC-DAD-QqTOF-MS) and determined by UHPLC-DAD. The honey samples contained nucleosides, nucleobases and their derivatives (adenine: 8.9 to 18.4 mg/kg, xanthine: 1.2 to 3.3 mg/kg, uridine: 17.5 to 51.2 mg/kg, guanosine: 2.0 to 4.1 mg/kg; mean amounts), aromatic amino acids (tyrosine: 7.8 to 263.9 mg/kg, phenylalanine: 9.5 to 64.1 mg/kg; mean amounts). The amounts of compounds significantly differed between some honey types. For example, canola honey contained a much lower amount of uridine (17.5 ± 3.9 mg/kg) than black locust where it was most abundant (51.2 ± 7.8 mg/kg). The presence of free nucleosides and nucleobases in different honey varieties is reported first time and supports previous findings on medicinal activities of honey reported in the literature as well as traditional therapy and may contribute for their explanation. This applies, e.g., to the topical application of honey in herpes infections, as well as its beneficial activity on cognitive functions as nootropic and neuroprotective, in neuralgia and is also important for the understanding of nutritional values of honey.

Structural and antioxidant analysis of Tartary buckwheat (Fagopyrum tartaricum Gaertn.) 13S globulin

BACKGROUND

The main component of buckwheat seed storage proteins is 13S globulin. In this study, Tartary buckwheat 13S globulin was separated and its structural features were investigated using Edman sequencing and matrix-assisted laser desorption / ionization time of flight mass spectrometry (MALDI-TOF-MS). The protective effect of its enzymatic hydrolysates against oxidative stress induced by H₂ O₂ was also evaluated to elucidate the antioxidant mechanism.

RESULTS

Results showed that the isolated Tartary buckwheat 13S globulin contained one acidic and one basic subunit, which were linked by a disulfide bond. Six Tartary buckwheat active peptides were obtained from the enzymatic hydrolysates of Tartary buckwheat 13S globulin acidic subunit with a molecular weight of 38 kDa, namely Pep-1, Pep-2, Pep-3, Pep-4, Pep-5, and Pep-6. Pre-treatment of cells with Tartary buckwheat active peptides maintained the redox state balance of HepG₂ cells and protected the activity of antioxidant enzymes in HepG₂ cells. The Tartary buckwheat active peptides improved oxidative stress in HepG₂ cells via the PPAR-α/HO-1 pathway.

CONCLUSION

These results provide an insight into the antioxidant mechanism of Tartary buckwheat 13S globulin and suggest that Tartary buckwheat active peptides can be used as a functional ingredient in the food industry. © 2019 Society of Chemical Industry.

Removal of lead, zinc and cadmium from contaminated soils with two plant extracts: Mechanism and potential risks

Screening appropriate washing agents to remediate soils contaminated with heavy metals is crucial for decreasing metal hazards posing to environment and human health. In this study, two plant washing agents-water-extracted from Fagopyrum esculentum and Fordiophyton faberi, were applied to remove soil Pb, Zn, and Cd by washing. Results indicated that metal removals augmented with increase of washing solution concentrations, decreased with increasing pH values of the solution and followed the pseudo-second-order model depending on contact duration. At concentration of 50 g/L, pH 3 and contact duration of 120 min, F. esculentum had higher removals of Pb (5.98-6.83%), Zn (21.82-27.94%), and Cd (39.90-40.74%) than those of F. faberi. And metal ions could be removed by binding with carboxyl, hydroxyl, amide, amine and aromatic groups in washing solutions. The potential risks of residual metals declined by 51.35-52.12% for mine soil and 48.51-49.96% for farmland soil with exchangeable and carbonate-bound fractions obviously extracted after a single washing (P < 0.05). And soil organic carbon and nutrients increased to some extent except for total phosphorus and available potassium. Moreover, soil phytotoxicity lowered except that some adverse effects on seed germination existed. Therefore, the water extract from F. esculentum is a promising washing agent for heavy metal removal.

Examining a synchrotron-based approach for in situ analyses of Al speciation in plant roots

Aluminium (Al) K- and L-edge X-ray absorption near-edge structure (XANES) has been used to examine Al speciation in minerals but it remains unclear whether it is suitable for in situ analyses of Al speciation within plants. The XANES analyses for nine standard compounds and root tissues from soybean (Glycine max), buckwheat (Fagopyrum tataricum), and Arabidopsis (Arabidopsis thaliana) were conducted in situ. It was found that K-edge XANES is suitable for differentiating between tetrahedral coordination (peak of 1566 eV) and octahedral coordination (peak of 1568 to 1571 eV) Al, but not suitable for separating Al binding to some of the common physiologically relevant compounds in plant tissues. The Al L-edge XANES, which is more sensitive to changes in the chemical environment, was then examined. However, the poorer detection limit for analyses prevented differentiation of the Al forms in the plant tissues because of their comparatively low Al concentration. Where forms of Al differ markedly, K-edge analyses are likely to be of value for the examination of Al speciation in plant tissues. However, the apparent inability of Al K-edge XANES to differentiate between some of the physiologically relevant forms of Al may potentially limit its application within plant tissues, as does the poorer sensitivity at the L-edge.

Effect of buckwheat extracts on acrylamide formation and the quality of bread

BACKGROUND

The presence of acrylamide in food has attracted wide attention and has raised concerns due to its potential toxic and carcinogenic effects. The phenolic compounds in buckwheat display strong antioxidant activity, which may affect the acrylamide levels. The aims of this study were to evaluate the effect of buckwheat extracts on acrylamide formation and the quality of the bread, and to investigate possible inhibitory mechanisms.

RESULTS

The extracts from Tartary buckwheat seeds, Tartary buckwheat sprouts, common buckwheat seeds, and common buckwheat sprouts reduced acrylamide level in bread by 23.5, 27.3, 17.0, and 16.7%, respectively. In addition, all four buckwheat extracts significantly (P < 0.05) reduced acrylamide levels in the asparagine / glucose system. There were significant positive correlations between total phenolic compound content, the antioxidant activity of the extracts, and the reduction in the acrylamide level. Evaluation of the organoleptic and textural properties indicated that the addition of the extracts did not significantly affect the crust color, aroma, taste, crumb appearance, and hardness of the bread.

CONCLUSION

This study showed that proper use of buckwheat extracts can reduce acrylamide levels in bread without having a significant impact on their properties. The study also revealed that a possible acrylamide formation inhibitory mechanism involved the Maillard reaction through the asparagine / glucose pathway. The study also provided useful information for the further application of buckwheat in improving food safety. © 2019 Society of Chemical Industry.

Combined Buckwheat d-Fagomine and Fish Omega-3 PUFAs Stabilize the Populations of Gut Prevotella and Bacteroides While Reducing Weight Gain in Rats

Some functional food components may help maintain homeostasis by promoting balanced gut microbiota. Here, we explore the possible complementary effects of d-fagomine and ω-3 polyunsaturated fatty acids (ω-3 PUFAs) eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA 1:1) on putatively beneficial gut bacterial strains. Male Sprague–Dawley rats were supplemented with d-fagomine, ω-3 PUFAs, or both, for 23 weeks. Bacterial subgroups were evaluated in fecal DNA by quantitative real-time polymerase chain reaction (qRT-PCR) and short-chain fatty acids were determined by gas chromatography. We found that the populations of the genus Prevotella remained stable over time in animals supplemented with d-fagomine, independently of ω-3 PUFA supplementation. Animals in these groups gained less weight than controls and rats given only ω-3 PUFAs. d-Fagomine supplementation together with ω-3 PUFAs maintained the relative populations of Bacteroides. ω-3 PUFAs alone or combined with d-fagomine reduced the amount of acetic acid and total short-chain fatty acids in feces. The plasma levels of pro-inflammatory arachidonic acid derived metabolites, triglycerides and cholesterol were lower in both groups supplemented with ω-3 PUFAs. The d-fagomine and ω-3 PUFAs combination provided the functional benefits of each supplement. Notably, it helped stabilize populations of Prevotella in the rat intestinal tract while reducing weight gain and providing the anti-inflammatory and cardiovascular benefits of ω-3 PUFAs.

Comparison of berry juice concentrates and pomaces and alternative plant proteins to produce spray dried protein-polyphenol food ingredients

Spray dried functional food ingredients were prepared by complexing alternative plant protein sources - buckwheat flour alone or blended with pea and rice proteins, with polyphenol sources - blueberry, cranberry and purple muscadine grape extracts from juice concentrates and pomaces - to create colloidal aggregate powders. When fruit pomaces (rather than juice concentrates) were used as polyphenol resources, solid recovery was significantly enhanced, especially for matrices made with pea protein, buckwheat flour or pea-buckwheat blends (over two fold for pea protein-berry pomace aggregates). Polyphenol content and DPPH radical scavenging capacity were, in general, significantly greater for pomace-derived protein-polyphenol aggregates compared to those made with juice concentrates. In particular, the particles produced with muscadine grape pomace presented the highest (p < 0.05) phenolic content (147.3-174.3 mg g-1, 19.4-20.4 mg g-1 and 16.3-21.4 mg g-1 for total phenolic content, anthocyanins and proanthocyanidins respectively), and antioxidant activity (408.9-423.3 μmol TE per g) as well as good spray drying yield (38.6-63.4%). Buckwheat flour, despite its relatively low protein content (13.7%) relative to pea and rice protein isolates (84% and 89%, respectively) still demonstrated high capacity for sorption of flavonoid phytoactive compounds from the berry fruits. These results suggest an efficient plant-based approach to produce value-added protein-polyphenol aggregates with broad utility as healthy food ingredients.

Metabolite Profiling and Transcriptome Analyses Provide Insights into the Flavonoid Biosynthesis in the Developing Seed of Tartary Buckwheat (Fagopyrum tataricum)

Tartary buckwheat (Fagopyrum tataricum) seeds are rich in flavonoids. However, the detailed flavonoid compositions and the molecular basis of flavonoid biosynthesis in tartary buckwheat seeds remain largely unclear. Here, we performed a combined metabolite profiling and transcriptome analysis to identify flavonoid compositions and characterize genes involved in flavonoid biosynthesis in the developing tartary buckwheat seeds. In total, 234 flavonoids, including 10 isoflavones, were identified. Of these, 80 flavonoids were significantly differential accumulation during seed development. Transcriptome analysis indicated that most structural genes and some potential regulatory genes of flavonoid biosynthesis were significantly differentially expressed in the course of seed development. Correlation analysis between transcriptome and metabolite profiling shown that the expression patterns of some differentially expressed structural genes and regulatory genes were more consistent with the changes in flavonoids profiles during seed development and promoted one SG7 subgroup R2R3-MYB transcription factors (FtPinG0009153900.01) was identified as the key regulatory gene of flavonoid biosynthesis. These findings provide valuable information for understanding the mechanism of flavonoid biosynthesis in tartary buckwheat seeds and the further development of tartary buckwheat health products.

Alteration of phenolic profiles and antioxidant capacities of common buckwheat and tartary buckwheat produced in China upon thermal processing

BACKGROUND

Buckwheat products are receiving increasing attention because of their high nutritive values and significant health-promoting properties. In the present study, 15 buckwheat products grown in different parts of China were investigated. Representative common or tartary buckwheat samples were further subjected to soaking, roasting, microwave cooking, boiling and steaming treatments. Colorimetric analyses and high-performance liquid chromatography (HPLC) analyses were performed to determine the phenolic profiles and antioxidant capacities of the raw and thermally processed buckwheat samples, respectively.

RESULTS

Tartary buckwheat exhibited a remarkably higher total phenolic content (TPC), total flavonoid content (TFC), 2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging activity and ferric reducing antioxidant power (FRAP) compared to common buckwheat, although there were no significant differences between their 2,2'-azino-di-(3-ethylbenzthiazoline sulfonic acid) (ABTS) free radical scavenging capacity. All thermal treatments, particularly microwave cooking, contributed to the greatest losses of phenolics and antioxidant capacities in the common buckwheat samples, whereas boiling and steaming usually resulted in the lowest losses. For the tartary buckwheat samples, all thermal treatments (except roasting), especially boiling and steaming, led to significant increases in TPC, TFC, DPPH free radical scavenging activity, FRAP and ABTS free radical scavenging capacity. However, HPLC analyses indicated that all thermal treatments, especially microwave cooking, gave rise to the greatest losses of the total content of 14 phenolic acids and three flavonoids, whereas boiling led to the lowest losses.

CONCLUSION

Both steaming and boiling treatments are recommended when preparing common or tartary buckwheat food products because they can minimize thermal degradation or promote their phenolic compounds and antioxidant capacities to the greatest extent. © 2019 Society of Chemical Industry.

The Effect of Tartary Buckwheat Flavonoids in Inhibiting the Proliferation of MGC80-3 Cells during Seed Germination

Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn) is rich in functional compounds such as rutin, quercetin, d-chiro-inositol, dietary fiber, and essential amino acids. Electric field (EF) treatment before sprout germination results in physiological and chemical changes, and some alterations might lead to positive applications in plant seeds. MTT assay showed that the effect of total flavonoids on human gastric cancer cell line MGC80-3 was significantly changed after EF treatment for different germination days (3-7 days). Among them, the total flavonoids of tartary buckwheat (BWTF) on the third day had the most obvious inhibitory effect on MGC80-3 (p < 0.01). In addition, flow cytometry evidenced that different ratios of quercetin and rutin had effects on the proliferation of MGC80-3. The same content of quercetin and rutin had the best effect, reaching 6.18 ± 0.82%. The anti-cancer mechanism was mainly promoted by promoting the expression of apoptotic proteins. The expression of Bax/Bcl-2 and caspase-8 in MGC80-3 cells was mediated by BWTFs. This study has good research value for improving the biological and economic value of tartary buckwheat.

Biofortification of common buckwheat microgreens and seeds with different forms of selenium and iodine

BACKGROUND

The biofortification of crops can counteract human diseases, including selenium (Se) and iodine (I) deficiencies in the diet. Little is known about the effects of combinations of Se and I on microgreens and seeds, or on their accumulation in these tissues. The present study aimed to evaluate Se (SeO₃ ^2- , SeO₄ ^2- ) and I (I^- , IO₃ ^- ) biofortification of common buckwheat microgreens and seeds with respect to the effects of the addition of Se, I and Se + I on yield and on physiological and biochemical characteristics.

RESULTS

In combination treatments, microgreens yield (600-800 g m^-2 ) was 50-70% higher than for Se and I alone. The respiratory potential also increased by 60-120%. F_v /F_m was close to 0.8 in all samples. Se content [0.24 μg g^-1 dry weight (DW)] was 50% higher for combination treatments than for Se and I alone. I content was highest for IO₃ ^- treatment (216 μg g^-1 DW) and decreased in combination treatments with Se by 50%.

CONCLUSION

Biofortification of buckwheat microgreens with Se and I should be performed with care because there are synergistic and antagonistic effects of these elements with respect to their accumulation. IO₃ ^- for the biofortification of microgreens should be kept low to prevent exceeding the recommended daily intake of I. © 2019 Society of Chemical Industry.

Buckwheat Antifungal Protein with Biocontrol Potential To Inhibit Fungal ( Botrytis cinerea) Infection of Cherry Tomato

A 11 kDa antifungal protein FEAP was purified from buckwheat ( Fagopyrum esculentum) seed extract with a procedure involving (NH₄)₂SO₄ precipitation and chromatography on SP-Sepharose, Affi-gel blue gel, Mono S, and Superdex peptide. Its N-terminal sequence was AQXGAQGGGAT, resembling those of buckwheat peptides Fα-AMP1 and Fα-AMP2. FEAP exhibited thermostability (20-100 °C) and acid resistance (pH 1-5). Its antifungal activity was retained in the presence of 10-150 mmol/L of K⁺, Mn²⁺, or Fe³⁺ ions, 10-50 mmol/L of Ca²⁺ or Mg²⁺ ions, and 50% methanol, 50% ethanol, 50% isopropanol, or 50% chloroform. Its half-maximal inhibitory concentrations toward spore germination and mycelial growth in Botrytis cinerea were 79.9 and 236.7 μg/mL, respectively. Its antifungal activity was superior to the fungicide cymoxanil mancozeb (248.1 μg/mL). FEAP prevented B. cinerea from infecting excised leaves, intact leaves, and isolated fruits of cherry tomato. Its mechanism involved induction of an increase in cell membrane permeability and a decrease in mitochondrial membrane potential.

Ectopic Expression of a Fagopyrum esculentum APETALA1 Ortholog only Rescues Sepal Development in Arabidopsis ap1 Mutant

Fagopyrum esculentum (Polygonaceae: Caryophyllales) exhibits an undifferentiated perianth comprising five showy tepals, which does not completely correspond to the perianth differentiated into typical sepals and petals in most core eudicots. In Arabidopsis, the APETALA1 (AP1) gene is involved in specifying sepals and petals development. Here we isolated AP1 ortholog, FaesAP1, and a 2.2kb FaesAP1 promoter (pFaesAP1) from F. esculentum. FaesAP1 expression is mainly detectable in all floral organs and maintains at a high level when tepals elongate rapidly both in pin and thrum flowers. Moreover, the GUS reporter gene driven by pFaesAP1 was activated in flowers where the sepals were intense, but the petals very weak or absent. Additionally, FaesAP1 ectopic expression in Arabidopsis ap1-10 mutant rescues sepal development fully, obviously prompting early flowering, but failing to complement petal development. In this study, evidence was provided that the showy tepals in the F. esculentum are homologs to core eudicots sepals. Furthermore, these findings show a different perianth identity program in Caryophyllales, suggesting that AP1 orthologs involved in petal development may evolve independently across different clades of core eudicots. Our results also suggest that FaesAP1 holds potential for biotechnical engineering to develop early flowering varieties of F. esculentum.

The Impact of Processing Parameters on the Content of Phenolic Compounds in New Gluten-Free Precooked Buckwheat Pasta

Buckwheat is a generous source of phenolic compounds, vitamins and essential amino acids. This paper discusses the procedure of obtaining innovative gluten-free, precooked pastas from roasted buckwheat grains flour, a fertile source of natural antioxidants, among them, phenolic acids. The authors also determined the effect of the extruder screw speed and the level of moisture content in the raw material on the quantity of free phenolic acids. The qualitative and quantitative analysis of phenolic acids in pasta was carried out using high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The chromatographic method was validated. For extracts with the highest total content of free phenolic acids and unprocessed flour from roasted buckwheat grain, the TLC-DPPH test was also performed to determine the antioxidant properties of the tested pasta. The level of moisture in the raw material had an impact on the content of phenolic acids. All pastas made from buckwheat flour moistened up to 32% exhibited a higher total content of free phenolic acids than other mixes moistened to 30 and 34% of water.

Enzyme-assisted development of biofunctional polyphenol-enriched buckwheat protein: physicochemical properties, in vitro digestibility, and antioxidant activity

BACKGROUND

During the last decade buckwheat was reported to have positive health effects. The present study investigated a high-polyphenol buckwheat protein (Fagopyrum esculentum Moench) prepared by enzyme-assisted processing, together with its physicochemical properties, in vitro digestibility, and antioxidant activity.

RESULTS

Buckwheat protein prepared from the synergistic enzymatic action of α-amylase and amyloglucosidase (E-BWP) had much higher polyphenol content than buckwheat protein prepared by isoelectric precipitation (I-BWP) or salt extraction (S-BWP). Rutin degraded during the process, giving quercetin. The protein constituents and amino acid composition of E-BWP were very similar to those of native buckwheat and were able to meet the WHO/FAO requirements for both children and adults. During in vitro digestion, E-BWP showed anti-digestive behavior with a nitrogen release that was lower than that of I-BWP or S-BWP. The positive effect of the polyphenol content of E-BWP resulted in a higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) content and greater reducing activity.

CONCLUSION

Buckwheat protein with high polyphenol content was successfully developed by enzyme-assisted processing. It had a well-balanced amino acid profile, antidigestive behavior, and high antioxidant activities. The results suggest that enzyme-assisted processing is promising in the production of polyphenol-enriched cereal protein, contributing higher functionality with good nutritional and antioxidant properties. © 2018 Society of Chemical Industry.

Fibre-enriched buckwheat pasta modifies blood glucose response compared to corn pasta in individuals with type 1 diabetes and celiac disease: Acute randomized controlled trial

AIM

People with type 1 diabetes and celiac disease (T1D&CD) have high blood glucose variability. Processed gluten-free foods have shown to induce a worse metabolic profile whereas naturally gluten-free foods may represent healthier options. On the other hand, dietary fibre has shown to reduce postprandial glycemic excursions in individuals with diabetes. Thus, we evaluated the acute effect of fibre-enriched buckwheat (FBP) and corn pasta (CP) on postprandial blood glucose response (PP-BGR).

METHODS

Ten adult patients with T1D&CD consumed two meals with the same amount of carbohydrate while differing only for pasta type (FBP or CP) preceded by the same insulin bolus. Participants utilized continuous glucose monitoring (CGM) and data over 6 h after meal were analyzed.

RESULTS

PP-BGR differed between the two meals, being significantly lower in the first period (0-3 h) after the CP than the FBP meal (iAUC: -38 ± 158 vs. 305 ± 209 mmol/L · 180 min, p = 0.040), whereas significantly higher in the second period (3-6 h) after the CP than the FBP meal (iAUC: 432 ± 153 vs. 308 ± 252 mmol/L · 180 min, p = 0.030). Overall, a less variable postprandial profile was observed after FBP than CP consumption.

CONCLUSIONS

In individuals with T1D&CD, the acute consumption of FBP induces significant differences in PP-BGR compared with CP that may be clinically relevant.