荞麦幼苗烫漂处理对其芦丁含量的影响

通过研究荞麦幼苗的烫漂处理对其芦丁含量的影响,确定出荞麦幼苗适宜的烫漂工艺条件,选出适宜烫漂的荞麦品种.试验结果表明:荞麦幼苗烫漂后,芦丁含量最佳的烫漂条件是:温度为70℃,时间为5 min.通辽市的日本大粒或者和武川县的茶色黎麻道品种均适合做荞麦发芽的原料.     

Feasibility of use of buckwheat flour as an ingredient in ginger nut biscuit formulation

Ginger nut biscuits are popular traditional biscuits which contain honey. In order to improve their nutritive profile and functionality, standard formulation based on wheat flour was substituted with buckwheat flour at three levels (30%, 40%, 50%). The quality attributes (chemical composition, microelements, bioactive compounds (total polyphenols, rutin, quercetin), antioxidative potential, textural and sensory properties) were compared to control biscuit (based on wheat flour) and biscuits substituted with rye at the same levels, since rye is used as an ingredient which improves the quality of ginger nut biscuits. Substitution with buckwheat flour resulted in a significant increase (p < 0.05) in protein, Zn, total polyphenols, antioxidative and chelating activity. Total dietary fibre, Cu, Mn and Fe contents also increased but did not exceed those in rye substituted biscuits. Consumption of 100 g of enriched biscuits could contribute to reaching ≈18–22% (buckwheat) and 16–17% (rye) of the estimated daily average total polyphenols intake, respectively. With the contents of rutin and quercetin at 3.96–6.57 mg/100 g d.b. and 0.087–0.214 mg/100 g d.b., respectively, buckwheat substituted biscuits may significantly contribute to total dietary flavonoid intake and meet the demands of preventive nutrition. Buckwheat enriched biscuits were rated higher regarding sensory attributes, softness and fracturability as compared to control but lower compared to rye supplemented biscuits.     

Effects of UV-B irradiation on the levels of anthocyanin,rutin and radical scavenging activity of buckwheat sprouts

The effects of various light compositions on the levels of anthocyanin, rutin and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity in buckwheat (Fagopyrum esculentum Moench) sprouts were evaluated. Dark-grown 6-day-old buckwheat sprouts were irradiated with different sources of visible and ultraviolet (UV) light. Particularly, we examined the effect of UV-B at wavelengths of 260–320 nm, 280–320 nm, and 300–320 nm on the production of flavonoid compounds, using multiple fluorescent lights and cylinders that filter out certain portions of the UV-B. The results showed that irradiation with UV-B > 300 nm increased the levels of anthocyanin and rutin, as well as the DPPH radical scavenging activity. When sprouts were irradiated with UV-B light at wavelengths of 260–300 nm, yellowing or withering occurred within 24 h of irradiation, indicating that wavelengths in this range are detrimental to the growth of buckwheat sprouts.     

Formation of an oxathiolone compound from rutin in acidic mixture of saliva and buckwheat dough: Possibility of its occurrence in the stomach

Buckwheat is used for various foods in the world. The objective of the present study is the determination of the chemical structure of a product formed in the acidic mixture of buckwheat dough and saliva that contains both nitrite and thiocyanate. In the mixture, an oxathiolone derivative of rutin, 5,7-dihydroxy-2-(7-hydroxy-2-oxobenzo[d][1,3]oxathiol-4-yl)-4H-chromen-4-one-3-O-β-rutinoside, was found. This compound seemed to be formed by the hydrolysis of a 2′-thiocyanate derivative of rutin, which was produced by the reaction of thiocyanate with the o-quinone generated by nitrous acid-dependent oxidation of rutin. Importance of the formation of the oxathiolone compound is discussed in relation to scavenging of the toxic quinone in the stomach.     

Distribution of phenolic compounds in the graded flours milled from whole buckwheat grains and their antioxidant capacities

Whole buckwheat grains were milled into 16 flour fractions using the gradual milling system and the phenolic compounds and the antioxidant capacity of each flour fraction were investigated. The phenolic and flavonoid contents of both free and bound phenolic extracts of buckwheat flour fractions significantly increased in the order from the fraction number 1 (phenolics less rich fraction) to the fraction number 16 (phenolics rich fraction). The phenolic compounds in buckwheat existed primarily in free form, whereas the flavonoids existed in grain in insoluble bound forms, bound to cell wall materials. The amounts of ferulic acid and rutin increased from 2.5 and 2.5 μg/g flour of the phenolics less rich fraction to 609.5 and 389.9 μg/g flour of the phenolics rich fraction of grain, respectively. The higher phenolic contents in the phenolics rich fractions exhibited the stronger antioxidant capacity than the phenolics less rich fractions. As a result, the flour milled from the outer layers of buckwheat grains with large amount of phenolic compounds and antioxidant capacity are considered to have significant health benefits.     

Rutin content in buckwheat (Fagopyrum esculentum Moench) food materials and products

The rutin content of buckwheat products was compared to the rutin content in their raw materials, in order to evaluate their value for producing functional foods. There is much less rutin in noodles (78 mg/kg, d.w.b. – dry weight basis), than in the dark buckwheat flour (218 mg/kg, d.w.b.) from which they are produced. One of the possible explanations is the presence of the rutin degrading enzyme. In raw (uncooked) groats there is 230 mg/kg (d.w.b.) of rutin and in precooked groats, 88 mg/kg (d.w.b.). In buckwheat beer and vinegar there is a negligible content of rutin. Buckwheat leaf flour contains about 2700 mg/kg (d.w.b.) rutin, and is thus a suitable material for enriching functional foods, giving it the potential for preventive nutrition.     

苦荞茶和荞麦面条中芦丁及槲皮素含量分析

采用高效液相色谱法分析苦荞茶和荞麦面条中的芦丁和槲皮素含量.结果表明:造粒型和非造粒型(全麦和全胚)苦荞茶中芦丁和槲皮素的含量(质量分数)具有明显差异,非造粒型苦荞茶中芦丁的质量分数较高(0.518 3％～0.850 6％),槲皮素的质量分数较低(0.0573％～0.252 1％);而造粒型苦荞茶和荞麦面条中槲皮素的质量分数较高(0.481 6％～1.022 2％,0.034 9％～0.072 0％),芦丁的质量分数较低(0.029 7％～0.031 4％,0.008 1％～0.024 4％),这可能是由于荞麦中存在的芦丁降解酶分解芦丁产生槲皮素的缘故.由此可见,并非所有的苦荞茶和荞麦面条都是以芦丁作为主要的黄酮类物质,单纯以芦丁和总黄酮的质量分数来评价荞麦制品的品质是不准确的.     

Evaluation of the in vitro inhibitory effects of buckwheat enhanced wheat bread extracts on the formation of advanced glycation end-products (AGEs)

In this study, the inhibitory effects of extracts from buckwheat enhanced wheat breads, on the formation of fluorescent advanced glycation end-products (AGEs) were studied in bovine serum albumin (BSA)/glucose and BSA/methylglyoxal (MGO) systems. Correlations with total phenolic compounds (TPC), total flavonoids (TF) as well as rutin (Ru) and quercetin (Q) contents were also identified.     

Metabolism of quercetin and rutin by the pig caecal microflora prepared by freeze-preservation

Several studies confirm a protection of cardiovascular diseases and certain forms of cancer by dietary flavonoid intake. The bioavailability of flavonoids is influenced by the metabolism of the microflora in the intestine. Using a new in vitro model system the deglycosylation of the flavonol rutin and the degradation of its aglycone quercetin were investigated by using fresh pig caecal inocula in comparison to inocula prepared before by freeze-preservation between 6 wk and 5 months. The incubation experiments led to the same pattern of phenolic degradation products in comparable amounts in both preparations using HPLC-DAD and GC-flame ionization detection (GC-FID) or GC-MS detection within 24-48 h of incubation. With the preservation of the microbial vitality and the metabolic efficiency by freeze-preparation over several months the experimental design of microbial metabolism studies will be independent in time and locality.     

蒸制对冷冻荞麦熟面品质的影响研究

为了改善冷冻荞麦熟面的品质特性,采用汽蒸的方式对其进行预处理,研究蒸面预处理对冷冻荞麦熟面品质(面条吸水率、蒸煮损失及质构特性)的影响。同时采用快速黏度分析仪(RVA)和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)分析蒸面预处理对面条的糊化特性及蛋白质亚基结构的影响。结果表明,汽蒸处理能显著降低面条的蒸煮损失,提高其复热后的硬度、弹性和咀嚼性,并且蒸制3 min时,其总蒸煮损失达到最小值。RVA分析表明,随着汽蒸时间的增加,淀粉的崩解值和峰值黏度降低,而糊化温度增加。SDS-PAGE图谱显示,随着蒸面时间的延长,低分子质量亚基条带的颜色变浅,说明汽蒸可能诱导其发生了交联聚合行为。因此,蒸面预处理可以提高面条的蒸煮特性和质构特性,改善冷冻荞麦熟面的品质特性。     

Preparation and properties of rutin-hydrolyzing enzyme from tartary buckwheat seeds

A rutin hydrolyzing enzyme (RHE) was isolated from Fagopyrum tataricum Moench seeds by using ammonium sulphate fractionation, anion exchange and size exclusion chromatography. The purified RHE has an apparent molecular weight of about 70 kDa determined by SDS-PAGE, with an isoelectric point (pI) (determined by isoelectric focusing) of 6.7. RHE has a specific catalytic activity toward rutin when incubated together with rutin at 37 °C for 30 min in the presence of 20% ethanol, and its K_m value for rutin is 1.04 × 10⁻³ M. The RHE catalytic product analyzed by HPLC displayed high similarity with quercetin and this is confirmed by ¹H NMR spectroscopy and LC-ESI-MS/MS, suggesting that the RHE hydrolysis product is quercetin. These results suggest that the RHE from tartary buckwheat seeds is a specific rutin-hydrolyzing enzyme, providing a new enzymatic preparation method for quercetin.     

Evaluation of the performance of flours from cross- and self-pollinating Canadian common buckwheat (Fagopyrum esculentum Moench) cultivars in soba noodles

Two Canadian cross-pollinating common buckwheat (Fagopyrum esculentum Moench) varieties, Koban and Koto, and two self-pollinating lines, BR01 and BR06, were dehulled and roller milled on a pilot mill to produce three distinct milled products, white flour, dark flour and whole groat flour. The white flours contained mostly starch (79.2–87.2%), whereas the dark flours were rich in proteins (37.1–38.7%), dietary fibre (15.2–22.0%), ash (5.49–5.99%), and fagopyritols (1420–2220 mg/100 g). The buckwheat flours were blended with wheat flour (Canada Western Red Spring straight grade flour) at 60:40 ratios and evaluated for soba noodle properties. Significant differences in milling properties, and in raw noodle colour and texture were detected among cultivars, although the impact of flour type on noodle properties was far greater. The self-pollinating lines exhibited comparable milling and soba noodle properties to Koban. Koto exhibited slightly higher white flour yield and generally firmer noodle texture compared to the other lines. White flours produced the brightest noodles, followed by whole groat and dark flours. Dark flours yielded the thickest cooked noodles with the largest maximum cutting stress and greatest resistance to compression. Noodles prepared with white flour offered the best chewiness, springiness and recovery parameters. Soba noodles prepared with dark flours contained considerably higher amounts of minerals, proteins, dietary fibre, and fagopyritols than noodles prepared with white flour.     

Antioxidant activity of commercial buckwheat flours and their free and bound phenolic compositions

Commercial buckwheat flours were investigated for their antioxidant activities, free, and bound phenolic compositions using spectrophotometer, LC–ESI-IT-MS, and LC–ESI-Q-TOF-MS. Farinetta flour contained the highest free and bound phenolic contents, followed by Supreme, whole buckwheat, and Fancy flour, respectively. The 50% ethanol extraction achieved significantly higher free phenolic content compared with water and absolute alcohol. The absolute ethanol extraction contained considerable more bound phenolic and flavonoid compounds. A high extraction temperature increased the phenolic contents. The optimal solvent to solids ratio was 50:1, and the optimal extraction time was 5 h for flavonoids. The spectral method was reproducible for analysing the total flavonoid contents. The LC–ESI-Q-TOF-MS studies on whole buckwheat flour showed that p-coumaric and gallic acids were found in the bound phenolics along with isoquercitrin but were not present in the free phenolic compounds. The free flavonol-glycosides were found in whole buckwheat flour but not in any other buckwheat flours.     

Quality and antioxidant property of buckwheat enhanced wheat bread

Common buckwheat (Fagopyrium esculentum Moench) was used to substitute 15% of wheat flour to make buckwheat enhanced wheat breads. Proximate composition, physical quality, functional components and antioxidant properties of buckwheat enhanced wheat breads were analysed and compared with those of white bread. Specific volumes of three breads were 6.10–6.75 cm³/g. Buckwheat enhanced wheat bread showed lower lightness and whiteness index values and higher redness and yellowness values. On a seven-point hedonic scale, all sensory results were 5.33–5.91, indicating that three breads were moderately acceptable. No differences were found in appearance, colour and overall sensory attributes for three breads, whereas both buckwheat enhanced wheat breads were rated higher in flavour and mouth feel. Buckwheat enhanced wheat bread contained more rutin and quercetin as expected. Buckwheat enhanced wheat bread was good in antioxidant activity, reducing power and 1,1-diphenyl-2-picrylhydrazyl radical scavenging ability with unhusked buckwheat enhanced wheat bread being the most effective. Overall, buckwheat enhanced wheat bread could be developed as a food with more effective antioxidant properties.     

Physicochemical and structural characterisation of globulin and albumin from common buckwheat (Fagopyrum esculentum Moench) seeds

The physicochemical and conformational properties of globulin (BG) and albumin (BA) fractions from common buckwheat seeds were characterised, and compared with those of buckwheat protein isolate (BPI). The polyphenol contents were also evaluated. The polyphenol content in BA was much higher than that in BG, and most of the polyphenols in the BA was in the free form, whilst that in the BG and BPI was mainly in the protein-bound form. The BA had higher content of uncharged polar amino acids, but lower acidic amino acids than BG. The protein solubility-pH profile of the BG and BA were very different, especially at pH 4.0–6.0. Far-UV and near-UV CD and intrinsic fluorescence spectra indicated that the secondary and/or tertiary conformations of BA were much more flexible than those of BG, but also more easily affected by the polyphenols. The results indicated that the properties of BG and BA varied considerably, and were largely dependent upon their polyphenol levels and the interactions of the polyphenols and the proteins.     

挤压处理对苦荞粉理化特性及全苦荞挂面品质的影响

为提高全苦荞挂面的加工适应性、蒸煮和质构品质,对苦荞粉进行挤压预处理后与苦荞生粉混合制作全苦荞挂面,探究了挤压处理对苦荞粉的冷糊黏度及凝胶强度的影响,并结合面带、面条的质构品质及面条蒸煮特性探究挤压处理对全苦荞挂面加工性能及食用品质的影响。结果表明,经过挤压后苦荞粉的吸水性指数和水溶性指数分别增加了102.7%和87.5%以上,冷糊黏度显著增加（p<0.05）,挤压后苦荞粉在冷水中可形成凝胶,凝胶强度随挤压加水量的增加或温度的降低而升高;添加挤压苦荞粉促进了面带成型,面带的表面黏附力随苦荞粉冷糊黏度的增加而显著增加（p<0.05）,随挤压苦荞粉凝胶强度的增加,面带的抗拉伸力及面条的硬度和咀嚼性显著增加（p<0.05）,蒸煮损失率及断条率显著下降（p<0.05）。     

Improving the antioxidant activity of buckwheat (Fagopyrum tataricm Gaertn) sprout with trace element water

Trace element water (TEW) (100, 200, 300, 400 and 500 ppm) was used to grow buckwheat (Fagopyrum tataricm Gaertn) to evaluate whether the beneficial effects of trace elements on the antioxidant activity could be accomplished with the supplement of TEW. At 300 ppm, TEW significantly increased the Cu, Zn and Fe contents in buckwheat sprout, but not the Se and Mn contents. The levels of rutin, quercitrin and quercetin did not differ between buckwheat sprouts grown in TEW and de-ionized water (DIW). The ethanolic extract from buckwheat sprout grown in 300 ppm TEW showed higher DPPH radical scavenging activity, ferrous ion chelating activity, superoxide anion scavenging activity and inhibitory activity toward lipid peroxidation than that grown in DIW. The extract of the TEW group also enhanced intracellular superoxide dismutase activity and resulted in lower level of reactive oxygen species in human Hep G2 cells.     

荞麦醋发酵过程中芦丁含量变化规律研究

研究了以陕北荞麦为原料酿造食醋过程中主要功能成分芦丁的含量变化。实验表明,在酒精发酵阶段,随着发酵的进行发酵液中芦丁含量呈上升趋势,发酵残渣中芦丁含量呈下降趋势;而在醋酸发酵阶段,发酵液中芦丁含量呈下降趋势,发酵残渣中芦丁含量呈上升趋势。总芦丁含量没有明显变化。     

HPLC法测定苦荞叶中芦丁的含量

采用高效液相色谱法(HPLC)快速测定芦丁,其测定色谱条件为:色谱柱:Kromasil C18,(10μm,4.6×250mm);流动相:甲醇:水:冰乙酸(体积比为:40:60:1),流速:1.0mL/min;检测波长:330nm,柱温:室温20℃.线性范围50～500 μg/mL,R2=0.9999.在上述条件下对苦荞叶中所含芦丁进行了含量测定,分析结果表明,此法简单快速、高效灵敏、重现性好.