Effect of thermal processing for rutin preservation on the properties of phenolics & starch in Tartary buckwheat achenes

Formation and Application of Starch-Polyphenol Complexes: Influencing Factors and Rapid Screening Based on Chemometrics

Understanding the nuanced interplay between plant polyphenols and starch could have significant implications. For example, it could lead to the development of tailor-made starches for specific applications, from bakinag and brewing to pharmaceuticals and bioplastics. In addition, this knowledge could contribute to the formulation of functional foods with lower glycemic indexes or improved nutrient delivery. Variations in the complexes can be attributed to differences in molecular weight, structure, and even the content of the polyphenols. In addition, the unique structural characteristics of starches, such as amylose/amylopectin ratio and crystalline density, also contribute to the observed effects. Processing conditions and methods will always alter the formation of complexes. As the type of starch/polyphenol can have a significant impact on the formation of the complex, the selection of suitable botanical sources of starch/polyphenols has become a focus. Spectroscopy coupled with chemometrics is a convenient and accurate method for rapidly identifying starches/polyphenols and screening for the desired botanical source. Understanding these relationships is crucial for optimizing starch-based systems in various applications, from food technology to pharmaceutical formulations.

Multi-omics identification of a key glycosyl hydrolase gene FtGH1 involved in rutin hydrolysis in Tartary buckwheat (Fagopyrum tataricum)

Rutin, a flavonoid rich in buckwheat, is important for human health and plant resistance to external stresses. The hydrolysis of rutin to quercetin underlies the bitter taste of Tartary buckwheat. In order to identify rutin hydrolysis genes, a 200 genotypes mini-core Tartary buckwheat germplasm resource was re-sequenced with 30-fold coverage depth. By combining the content of the intermediate metabolites of rutin metabolism with genome resequencing data, metabolite genome-wide association analyses (GWAS) eventually identified a glycosyl hydrolase gene FtGH1, which could hydrolyse rutin to quercetin. This function was validated both in Tartary buckwheat overexpression hairy roots and in vitro enzyme activity assays. Mutation of the two key active sites, which were determined by molecular docking and experimentally verified via overexpression in hairy roots and transient expression in tobacco leaves, exhibited abnormal subcellular localization, suggesting functional changes. Sequence analysis revealed that mutation of the FtGH1 promoter in accessions of two haplotypes might be necessary for enzymatic activity. Co-expression analysis and GWAS revealed that FtbHLH165 not only repressed FtGH1 expression, but also increased seed length. This work reveals a potential mechanism behind rutin metabolism, which should provide both theoretical support in the study of flavonoid metabolism and in the molecular breeding of Tartary buckwheat.

Impact of exopolysaccharides-producing lactic acid bacteria on the chemical, rheological properties of buckwheat sourdough and the quality of buckwheat bread

Exopolysaccharides (EPS) produced in situ by lactic acid bacteria (LAB) during sourdough fermentation have the potential to replace hydrocolloids in gluten-free sourdoughs. This study investigated effects of an EPS-producing Weissella cibaria NC516.11 fermentation on chemical, rheological properties of sourdough and the quality of buckwheat bread. Results indicate that the buckwheat sourdough fermentation by W. cibaria NC516.11 had lower pH (4.47) and higher total titrable acidity (8.36 mL) compared with other groups, and the polysaccharide content reached 3.10 ± 0.16 g/kg. W. cibaria NC516.11 can significantly improve the rheological properties and viscoelastic properties of sourdough. Compared with control group, the baking loss of NC516.11 group bread decreased by 19.94%, specific volume increased by 26.03%, and showed good appearance and cross-sectional morphology. Scanning electron micrograph revealed an intact and less porous cell structure. Meanwhile, W. cibaria NC516.11 significantly improved the texture of the bread and reduced the hardness and moisture loss during storage.

High-quality Fagopyrum esculentum genome provides insights into the flavonoid accumulation among different tissues and self-incompatibility

Common buckwheat (Fagopyrum esculentum) and Tartary buckwheat (Fagopyrum tataricum), the two most widely cultivated buckwheat species, differ greatly in flavonoid content and reproductive mode. Here, we report the first high-quality and chromosome-level genome assembly of common buckwheat with 1.2 Gb. Comparative genomic analysis revealed that common buckwheat underwent a burst of long terminal repeat retrotransposons insertion accompanied by numerous large chromosome rearrangements after divergence from Tartary buckwheat. Moreover, multiple gene families involved in stress tolerance and flavonoid biosynthesis such as multidrug and toxic compound extrusion (MATE) and chalcone synthase (CHS) underwent significant expansion in buckwheat, especially in common buckwheat. Integrated multi-omics analysis identified high expression of catechin biosynthesis-related genes in flower and seed in common buckwheat and high expression of rutin biosynthesis-related genes in seed in Tartary buckwheat as being important for the differences in flavonoid type and content between these buckwheat species. We also identified a candidate key rutin-degrading enzyme gene (Ft8.2377) that was highly expressed in Tartary buckwheat seed. In addition, we identified a haplotype-resolved candidate locus containing many genes reportedly associated with the development of flower and pollen, which was potentially related to self-incompatibility in common buckwheat. Our study provides important resources facilitating future functional genomics-related research of flavonoid biosynthesis and self-incompatibility in buckwheat.

Phytochemical properties and health benefits of pregelatinized Tartary buckwheat flour under different extrusion conditions

This work investigated the phytochemical properties and health benefits of Tartary buckwheat flour obtained with different extrusion conditions including high, medium, and low temperature. Extrusion significantly decreased the fat content and changed the original color of Tartary buckwheat flour. The contents of protein, total flavonoids, and D-chiro-inositol were affected by the extrusion temperature and moisture. Extrusion significantly decreased the total flavonoids and flavonoid glycosides contents, while it significantly increased aglycones. Compared to native Tartary buckwheat flour and pregelatinization Tartary buckwheat flour obtained with traditional extrusion processing technology, the pregelatinization Tartary buckwheat flour obtained with improved extrusion processing technology contained higher aglycones and lower flavonoid glycosides, which had stronger antioxidant capacity, α-glucosidase inhibitory activity and relatively mild α-amylase inhibitory activity. Correlation analysis proved that the aglycone content was positively correlated with antioxidant and α-glucosidase inhibitory activities. These findings indicate that the pregelatinization Tartary buckwheat flour obtained with improved extrusion processing technology could be used as an ideal functional food resource with antioxidant and anti-diabetic potential.

An integrated strategy for anti-inflammatory quality markers screening of traditional Chinese herbal medicine Mume Fructus based on phytochemical analysis and anti-colitis activity

BACKGROUND

Mume Fructus (MF) is used in traditional Chinese herbal medicine (TCM) to treat chronic cough, prolonged diarrhea, and other inflammation-related diseases. It is processed from Prunus mume fruit (PM) by drying at low temperature according to the Chinese Pharmacopoeia. The standard quality control method includes measurement of citric acid content, which is not sufficient to determine its clinical efficacy. In addition, the quality markers, that would ensure consistent drug composition and stability during extraction and processing of the drug, are currently not available.

PURPOSE

This study sought to determine and analyze the bioactive compounds in MF and to establish the quality maker evaluation system, which would enable accurate assessment of different processing and extraction approaches for MF preparation.

STUDY DESIGN AND METHODS

First, a UPLC-QTOF-MS/MS method was established to identify the chemical constituents of PM and MF. Second, the 2,4,6-trinitrobenzenesulfonic acid (TNBS)-treated rats were used to assess anti-inflammatory activity of water and ethanol extracts of PM and MF. Third, correlation analysis and multivariate statistical analysis was used to seek the candidate quality markers of MF. Fourth, molecular docking was used to predict the potential mechanism of identified compounds for the anti-inflammatory activity. Finally, a UPLC method was established to quantify the selected quality markers in MF products, that were prepared by different drying processes.

RESULTS

99 components (28 newly reported) were identified from PM and MF. During the drying process several changes in the composition were observed; caffeoylquinic acids were degraded to p-coumaric acid, caffeic acid, protocatechuic acid, or p-hydroxybenzoic acid; multi-acetyl p-coumaroyl sucroses were degraded to mumeose R and p-coumaroyl-3-O-sucrose. On the other hand, contents of mumefural and amygdalin increased after drying process. In colitis rats, MF reduced more NO levels to greater extent in comparison to PM, which could be attributed to the presence of caffeic acid, p-coumaric acid, protocatechuic acid, p-hydroxybenzoic acid, mumefural, p-coumaroyl-3-O-sucrose, mumeose R, and amygdalin in MF. Moreover, water extracts were better than ethanol extracts in alleviating the IL-1β, IL-6, and IL-17 levels, possibly on account of citric acid and caffeoylquinic acids. The predicted mechanism of action could be through inhibition of the production of NLRP3, TLR4, and NF-κB proteins. Finally, 7 compounds (citric acid, 3-O-caffeoylquinic acid, 5-O-caffeoylquinic acid, 4-O-caffeoylquinic acid, caffeic acid, protocatechuic acid, and p-coumaric acid) were selected as quality markers of MF that could be used for the process quality control.

CONCLUSION

This study revealed the material basis of PM and MF for anti-colitis activity and discovered the quality markers of MF which could reflect the anti-inflammatory activity and the processing process of MF.

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.

Physical modification on the in vitro digestibility of Tartary buckwheat starch: Repeated retrogradation under isothermal and non-isothermal conditions

The effects of repeated retrogradation (RR, range from 1 to 3 times) at different temperatures (4 °C; 4/25 °C, with a 24 h interval; 25 °C) on the in vitro digestibility and structures of Tartary buckwheat starch (TS) were investigated in this study. Results demonstrated that TS treated by RR for 1 time under 4/25 °C contained the maximum content of slowly digestible starch (SDS, 35.25%); TS treated by RR for 3 times under 25 °C contained the maximum content of resistant starch (RS, 54.92%). As the increase of RR cycle times, the value of relative crystallinity, the ratios of 1047/1022 cm^-1 and 995/1022 cm^-1 increased, the starch pore wall thickened, and more smooth fragments appeared (observed by scanning electron microscope), while the value of melting temperature range trended to decrease. The crystallization type of TS changed from type "A" to a mixture of "B + V" after retrogradation treatment. Pearson correlation analysis revealed that the content of rapidly digestible starch (RDS) was negatively correlated with the ratio of 995/1022 cm^-1, transition temperatures, and enthalpy (P < 0.05). These results would supply a potential method for the preparation of starch with slow-digesting properties, also improve the utilization and expand the application of TS.

Tartary Buckwheat in Human Nutrition

Tartary buckwheat (Fagopyrum tataricum Gaertn.) originates in mountain areas of western China, and it is mainly cultivated in China, Bhutan, northern India, Nepal, and central Europe. Tartary buckwheat shows greater cold resistance than common buckwheat, and has traits for drought tolerance. Buckwheat can provide health benefits due to its contents of resistant starch, mineral elements, proteins, and in particular, phenolic substances, which prevent the effects of several chronic human diseases, including hypertension, obesity, cardiovascular diseases, and gallstone formation. The contents of the flavonoids rutin and quercetin are very variable among Tartary buckwheat samples from different origins and parts of the plants. Quercetin is formed after the degradation of rutin by the Tartary buckwheat enzyme rutinosidase, which mainly occurs after grain milling during mixing of the flour with water. High temperature treatments of wet Tartary buckwheat material prevent the conversion of rutin to quercetin.

Maillard Reaction Products in Gluten-Free Bread Made from Raw and Roasted Buckwheat Flour

The formation of Maillard reaction products (MRPs) in gluten-free bread made from roasted and raw buckwheat flour was examined. The levels of phenolic compounds such as flavonoids (catechin, naringenin, quercetin, rutin, and others) and phenolic acids (like 4-hydroxybenzoic, caffeic, dihydroxybenzoic, ferulic, gallic, syringic, vanillic, and p-coumaric) were measured using reversed-phase ultra-high performance liquid chromatography-electrospray ionization mass spectrometry (RP–UHPLC–ESI-MS). Early and advanced Maillard reaction products were analyzed using HPLC, whereas spectrofluorimetric analysis was used to determine the levels of fluorescent intermediate compounds (FIC). The total levels of phenolic compounds were higher in the case of buckwheat bread prepared from roasted buckwheat flour (156 and 140 µg/g of crumb and crust, respectively). Rutin, gallic acid, and catechin were the most abundant phenolic compounds detected in roasted buckwheat bread. The roasting process resulted in significantly lower radical scavenging capacities (ABTS) of the total phenolics and flavonoids in the buckwheat bread. Taking into consideration these Maillard reaction products, we observed a significant increase in FIC level in roasted buckwheat crumb and crust (at about 40%, and 38%, respectively). At the same time, the Nε-(carboxymethyl)lysine (CML) level did not change in roasted or raw buckwheat bread crumb, though in roasted buckwheat crust the concentration of CML increased by about 21%.

Release of characteristic phenolics of quinoa based on extrusion technique

Quinoa is rich in phenolics which are benefit for human health for their outstanding antioxidant capacity, anti-inflammatory property and special biological functions. However, most of phenolics existed as bound form that with low bioavailability in quinoa. In this study, extrusion technique was applied for the release of bound phenolics in red quinoa (RQ), and effects of extruded temperature (120 °C, 140 °C, 160 °C and 180 °C) on the release of characteristic phenolics of RQ was investigated as well. Phenolics both presented as free and bound forms were identified in RQ and extruded quinoa samples, and result showed rutin, ferulic acid and vanillic acid were most common. The content of bound phenolics in RQ was 155.52 mg/kg, however, in extruded red quinoa (ERQ) was 77.25 mg/kg (ERQ-140 °C)-84.08 mg/kg (ERQ-120 °C). In corresponding, free phenolics in RQ was 22.15 mg/kg, while in ERQ was 41.04 mg/kg (ERQ-140 °C)-47.25 mg/kg (ERQ-160 °C). In conclusion, extrusion was excellent for the release of bound phenolics in quinoas and the best extruded temperature was 160 °C. Extrusion technique was potential in the processing of quinoa.