Vicilin-like storage globulin from buckwheat (Fagopyrum esculentum Moench) seeds

An 8S storage globulin from buckwheat seed, which resembles the structure and features common to the vicilin-like family of seed storage proteins, was analyzed for this paper. It was found that expression of the 8S globulin gene precedes that of the 13S globulin (the main buckwheat storage protein) and starts from an early stage of buckwheat seed development (9-11 days after flowering), continuing to accumulate throughout seed development to contribute approximately 7% of total seed proteins. This protein fraction might be more interesting for biotechnological application than the 13S buckwheat legumin consisting of 23-25 kDa subunits reported to be the major buckwheat allergen. A partial cDNA was also isolated, showing high homology with cDNAs coding for vicilin-like storage proteins from various plant species, and its expression profile throughout seed development as well as in different buckwheat tissues was analyzed.     

Effects of lipase, lipoxygenase, peroxidase, and rutin on quality deteriorations in buckwheat flour

To investigate the effects of changes in lipase, lipoxygenase, peroxidase (POX), and rutin concentrations on the quality of buckwheat flour, 14 buckwheat varieties were stored for 0, 4, 10, and 30 days at 5 or 20 degrees C. During the storage period, lipase activity correlated to pH (significantly negative) and water-soluble acid (WSA) (significantly positive). The lipoxygenase 1 protein concentration had a negative correlation to WSA (significant at 0 and 4 storage days at 5 degrees C and at 0 and 10 storage days at 20 degrees C). POX had significant correlation to pH and peroxide value (POV) at 5 degrees C, whereas it was not significant at 20 degrees C. The rutin concentration had negative correlations to WSA (significant at 30 days of storage at 5 degrees C and at 4 days of storage at 20 degrees C). Thus, lipase activity plays an important role that relates to lipid degradation in quality deterioration of buckwheat flour.     

Partial Characterization of Buckwheat (Fagopyrum esculentum) Starch

Laboratory-isolated buckwheat (Fagopyrum esculentum) starch was compared to commercial corn and wheat starches. Buckwheat starch granules (2.9–9.3 μm) were round and polygonal with some holes and pits on the surface. Buckwheat starch had higher amylose content, waterbinding capacity, and peak viscosity, and it had lower intrinsic viscosity when compared with corn and wheat starches. Buckwheat starch also showed restricted swelling power at 85–95°C and lower solubility in water at 55–95°C and was more susceptible to acid and enzymatic attack. Gelatinization temperatures, determined by differential scanning calorimetry, were 61.1–80.1°C for buckwheat starch compared to 64.7–79.2°C and 57.1–73.5°C for corn and wheat starches, respectively. A second endotherm observed at 84.5°C was an amylose-lipid complex attributed to the internal lipids in buckwheat starch, as evidenced by selective extraction. The retrogradation of buckwheat, corn, and wheat starch gels was examined after storage at 25, 4, and -12°C for 1–15 days. In general, buckwheat starch retrogradation was slower than that of corn and wheat starch, but it increased as storage time increased, as did that of the other starch pastes. When the values of the three storage temperatures were averaged for each storage period analyzed, buckwheat starch gels showed a lower percentage of retrogradation than did corn and wheat starch gels. Buckwheat starch also had a lower percentage of water syneresis when stored at 4°C for 3–10 days and had better stability to syneresis after three freeze-thaw cycles at -12 and 25°C.     

荞麦籽粒生物力学性质及内芯黏弹性试验研究

针对可供相关作业机械设计参考的荞麦籽粒生物力学性质指标可用参数缺乏的现状,该文研究了优种荞麦籽粒的常规力学性质及芯粉黏弹性力学性质,并对相关影响因素进行了分析。试验测定了不同品种荞麦籽粒在不同含水率下的三轴尺寸、千粒质量、容重等基本物性参数,采用斜面仪、休止角测定装置测定了荞麦籽粒的滑动摩擦系数及休止角,应用DMA(Q800)动态力学性能分析仪测定了荞麦(粉状)的动态黏弹性,运用物性分析仪测定了荞麦籽粒的破坏力、破坏能等力学性质,利用摆锤式动载试验机测定了荞麦籽粒所能承受的最大撞击载荷。结果表明:同一品种荞麦籽粒的长、宽、高、千粒质量、几何平均径均随含水率的降低而减小,容重随着含水率的降低而增大;摩擦系数随含水率的降低而减小,籽粒与Q235钢板的摩擦系数最大,与7075铝合金板的次之,与304不锈钢板的最小;休止角随含水率的降低而减小;随着含水率的降低,破坏力、表观弹性模量和最大接触应力逐渐增大,变形量逐渐减小,破坏能呈上升趋势。而在相同含水率下,不同品种荞麦籽粒的物性参数及上述力学特性参数均呈现极显著差异(P0.0001)。荞麦粉末的储能模量随含水率的降低而增大,弹性性能提高,损耗模量和损耗正切随含水率的降低而减小,黏性性能降低。同一品种荞麦在相同含水率下,撞击载荷越大,破碎率越高;同一撞击载荷下,随着含水率的降低,籽粒的破碎率先减小后增大。研究结果可为荞麦收获及加工装备研制、参数优化提供基础依据。     

Molecular cloning, recombinant expression, and immunological characterization of a novel allergen from tartary buckwheat

Buckwheat is generally regarded as a nutritionally rich food source. However, earlier studies prove that it also causes allergies to subjects. Allergenic proteins with a strong IgE-binding activity have been identified in common buckwheat (CB) and a 24 kDa allergen (rTBa) in tartary buckwheat (TB). The objective of this research was to clone and express a novel allergen in tartary buckwheat and to evaluate its structure and immunological activity. The 1773 bp full-length cDNA was amplified and cloned from the total RNA of TB by polymerase chain reaction (PCR) and rapid amplification of cDNA ends (RACE) methods. Its nucleotide sequence had high similarity with legume-like 13S storage protein mRNA in CB. The deduced amino acid sequence included a putative signal peptide and 18 fragments as its epitope sites. The predicted full-length TB allergen sequence was found to have two domains, and the recombinant protein reacted with sera from patients with positive IgE binding to buckwheat and had a lower binding ability than the recombinant TBa and recombinant TBb (C- and N-terminal amino acid sequence of TBt codes for protein). This fact suggests that full-length TB allergen may hydrolyze to two domains in vivo, decreasing the IgE-binding ability.     

Determination of D-chiro-Inositol in tartary buckwheat using high-performance liquid chromatography with an evaporative light-scattering detector

A simple method for rapid determination of d- chiro-inositol (DCI) (a potent mediator of insulin metabolism) contained in tartary buckwheat ( Fagopyrum tataricum L. Gaench) was developed on the basis of high-performance liquid chromatography coupled to an evaporative light scattering detector (ELSD). DCI was separated from an extract of tartary buckwheat on an Alltech Prevail Carbohydrates ES 5 mum column. During postcolumn detection, DCI was detected by ELSD. The detection limit was 100 ng. This method was sensitive enough for determining DCI in tartary buckwheat and its related products.     

Antioxidant activity of tartary (Fagopyrum tataricum (L.) Gaertn.) and common (Fagopyrum esculentum moench) buckwheat sprouts

This study compared the differences of two types of buckwheat sprouts, namely, common buckwheat ( Fagopyrum esculentum Moench) and tartary buckwheat ( Fagopyrum tataricum (L.) Gaertn.), in general composition, functional components, and antioxidant capacity. The ethanol extracts of tartary buckwheat sprouts (TBS) had higher reducing power, free radical scavenging activity, and superoxide anion scavenging activity than those of common buckwheat sprouts (CBS). As for chelating effects on ferrous ions, CBS had higher values than TBS. Rutin was the major flavonoid found in these two types of buckwheat sprouts, and TBS was 5 fold higher in rutin than CBS. The antioxidant effects of buckwheat sprouts on human hepatoma HepG2 cells revealed that both of TBS and CBS could decrease the production of intracellular peroxide and remove the intracellular superoxide anions in HepG2 cells, but TBS reduced the cellular oxidative stress more effectively than CBS, possibly because of its higher rutin (and quercetin) content.     

外源硒对铅污染下荞麦生长及生理特性的影响

以荞麦‘右玉26’为材料,在防雨棚下进行盆栽试验,研究外源硒对土壤铅污染下荞麦幼苗的农艺性状及生理特性、成熟期各器官铅累积和产量的影响,旨在探讨硒对土壤铅胁迫下荞麦的生长发育、产量及铅在荞麦体内富集量的影响,为发现硒缓解重金属铅对植物的毒害作用提供理论依据,以期为农业区铅污染治理及荞麦生产提供有价值的思路和方法。试验采用2因素完全随机设计,设置3个土壤铅浓度(0 mg·L-1、500 mg·L-1、1 000 mg·L-1)、5个硒浓度(0 mg·kg-1、1 mg·kg-1、2.5 mg·kg-1、5 mg·kg-1和10 mg·kg-1)。研究结果表明:1)随铅浓度增加,荞麦的株高、总根长、干重、根系总面积、根系活力、叶绿素含量、叶绿素荧光参数、经济产量(千粒重、株粒数)均呈降低趋势。2)低浓度硒(1~2.5 mg·L-1)可缓解铅对荞麦的毒害,高浓度硒(5~10 mg·L-1)和铅为协同作用,加剧了对荞麦的毒害。3)硒浓度为2.5 mg·L-1时,缓解铅对荞麦毒害的效果最为明显,显著降低了铅胁迫下荞麦幼苗SOD和POD活性;降低成熟期荞麦各器官铅含量,各处理下荞麦各器官铅含量均表现为根茎叶种子;产量达到最大值。由此可见,外源硒可通过抑制荞麦对铅的吸收和转运,促进荞麦幼苗叶片的光合作用、提高叶片叶绿素含量和根系活力等途径来增强荞麦对铅胁迫的耐性。对本研究所用的5种浓度来说,缓解效果最佳的硒浓度为2.5 mg·L-1。     

Determination of rutin, catechin, epicatechin, and epicatechin gallate in buckwheat Fagopyrum esculentum Moench by micro-high-performance liquid chromatography with electrochemical detection

A simple and sensitive method has been developed for determining rutin, catechin, epicatechin, and epicatechin gallate in buckwheat (Fagopyrum esculentum Moench) flour and seeds by micro-high-performance liquid chromatography with electrochemical detection. Chromatography was performed using an octadecylsilica column, acetonitrile-water-formic acid (13:87:1, v/v/v) as a mobile phase, and an applied potential at +0.5 V vs Ag/AgCl. We found that Japanese buckwheat flour contains rutin (12.7 mg/100 g), catechin (3.30 mg/100 g), epicatechin (20.5 mg/100 g), and epicatechin gallate (1.27 mg/100 g). The relative standard deviations for rutin, catechin, epicatechin, and epicatechin gallate peak heights were less than 0.86% (n = 5). The detection limit of rutin was 0.86 ng/mL. Moreover, the present method was applied to the distribution analysis of these compounds in buckwheat seed. The embryo proper and cotyledons of a mature buckwheat seed contained rutin with the highest concentration as compared to other parts. This method is useful in determining rutin, catechin, epicatechin, and epicatechin gallate in buckwheat with a small amount of sample for quality control in the food industry.     

Effect of buckwheat extract on the antioxidant activity of lipid in mouse brain and its structural change during in vitro human digestion

This study was conducted to investigate the effects of buckwheat ( Fagopyrum esculentum Moench cv. Yangjul No. 2) extract on the antioxidant activity of lipids in mouse brain and the structural change during in vitro human digestion. Buckwheat was collected from a wild farm and extracted with water. The buckwheat extracts were then passed through an in vitro human digestion model that simulated the composition of the mouth, stomach, and small intestine juice. The results confirmed that the main phenolics of buckwheat extract were rutin, quercitrin, and quercetin. The rutin content increased with digestion of the buckwheat (from 48.82 to 96.34 μg/g) and rutin standard samples (from 92.76 to 556.56 μg/g). Antioxidant activity was more strongly influenced by in vitro human digestion of both buckwheat and rutin standard. After digestion by the small intestine, the antioxidant activity values were dramatically increased (from 5.06 to 87.82%), whereas the antioxidant activity was not influenced by digestion in the stomach for both buckwheat extract and rutin standard. Inhibition of lipid oxidation of buckwheat in mouse brain lipids increased after digestion in the stomach for both buckwheat extract and the rutin standard. The major finding of this study was that in vitro human digestion may be an important modulator of the antioxidant capacity of buckwheat and that this may be because in vitro human digestion increased the antioxidative activity via an increase in antioxidants such as rutin and quercetin.     

电解水对荞麦芽酚酸含量及抗氧化能力的影响

为了能够更好地将发芽荞麦用作制备功能食品的原料,本研究采用理化指标不同的电解水制备荞麦芽,考察荞麦的发芽率及芽长、总酚含量、DPPH和ABTS自由基清除能力,以及铁离子还原力在发芽期间的动态变化,并分析各处理组发芽第7天荞麦芽中游离酚和结合酚种类和含量。结果表明,在7 d观测期内,电解水有利于荞麦发芽及生长。不同评价方法测定荞麦芽抗氧化能力的结果显示,pH值11.13电解水处理组发芽1~3 d荞麦芽总酚含量及抗氧化水平均显著高于对照组(P<0.05),而pH值3.21、pH值5.02和pH值9.02电解水处理组发芽5~7 d荞麦芽总酚含量及抗氧化水平均显著高于对照组(P<0.05)。各处理组荞麦芽中主要的游离酚均为绿原酸,且电解水处理组荞麦芽游离绿原酸含量均显著高于对照组(P<0.05)。自来水处理组荞麦芽主要结合酚为香豆酸,而电解水处理组荞麦芽主要结合酚为咖啡酸。本研究结果为电解水应用于功能性荞麦芽的制备提供了理论依据。     

Comparison of spectrophotometric and electrochemical methods for the evaluation of the antioxidant capacity of buckwheat products after hydrothermal treatment

This paper reports the use of spectrophotometric and voltammetric methods for the determination of the antioxidant capacity of buckwheat and its products originated from a technological line of a buckwheat roasted groats producer. 80% methanol extracts from raw and roasted buckwheat and groats and hulls obtained from roasted buckwheat were used. The spectrophotometric methods included (1) free radical scavenging activities of the extracts against ABTS*+ radical cation (TEAC) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH RSA) and (2) determination of reducing capacity by the means of Folin-Ciocalteu reagent (FCR) application. The radical scavenging activities of the extracts were also investigated using a voltammetric assay. Moreover, the flavonoids profiles of the studied materials were provided. Buckwheat roasting caused a decrease in TEAC, DPPH RSA, and FCR reducing capacity by 70%. The lowest TEAC, DPPH RSA, and FCR reducing capacities were noted for roasted groats. Both DPPH RSA and TEAC methods were highly positively correlated with the FCR reducing capacity assay (r = 0.98 and r = 0.99). Cyclic voltammograms of analyzed buckwheat extracts were useful for evaluation of the antioxidant capacity. The total charge below the anodic current waveform was correlated with the data obtained by TEAC (r = 0.770), DPPH RSA (r = 0.88), and FCR reducing capacity (r = 0.81). The changes in the antioxidant capacity of buckwheat and its products followed the changes in flavonoids composition. In particular, the concentration of flavonoids was related to measurements by cyclic voltammetry.     

黑苦荞米黄酮提取工艺优化及其降血糖活性研究

为了获得合适的黑苦荞米黄酮提取工艺,该文采用单因素试验和响应面设计,选择乙醇体积分数、料液比、提取时间、提取温度4个因素,优化黑苦荞米黄酮提取工艺。试验结果表明,黑苦荞米黄酮的最佳提取条件是:乙醇体积分数54%,料液比1:24 g/m L,提取时间62 min,提取温度71℃。在此条件下,理论黄酮得率为2.21%,实际黄酮得率为2.20%,相对误差为0.45%。在此基础上进一步研究了黑苦荞米黄酮的α-淀粉酶抑制活性,结果表明7.5 mg/m L的黑苦荞米黄酮对α-淀粉酶活性的抑制率为54.05%,与二甲双胍(5 mg/m L)效果相当;此外,与空白对照相比,50μg/m L黑苦荞米黄酮能显著(P0.05)提高肝脏细胞Hep G2的葡萄糖消耗量(48.73%),并促进肝脏细胞糖原的合成。研究结果表明,黑苦荞米黄酮具有较好的辅助降血糖功效。     

Effect of Extrusion Process Parameters on the Quality of Buckwheat Flour Mixes

A response surface analysis using a second-order central composite design was used to study the effect of extrusion process parameters on the extrudate quality of three blends containing buckwheat flour. The extrudates were prepared as three blends. Blend 1 was a 55:40:5 (w/w) mix of light buckwheat flour, wheat flour, and nonfat dry milk (NFDM). Blend 2 was a 40:55:5 mix of light buckwheat flour, corn meal, and NFDM. Blend 3 was a 30:60:10 mix of light buckwheat flour, corn meal, and NFDM. The blends were processed in a twin-screw extruder with factorial combinations of the parameters including: process temperatures of 95–150°C, dough moisture of 15–22%, and screw speeds of 260–390 rpm. The linear components alone significantly explained most of the variation of expansion index, bulk density, water absorption, and breaking strength. The greatest amount of variability was explained by process temperature for blend 1. Dough moisture accounted for the greatest amount of variation for blends 2 and 3. Maximum predicted expansion index values and high water absorption percentages were obtained at low dough moisture levels. Dough moisture and process temperatures were the most important factors predicting bulk density. Sensory evaluation of texture, color, flavor, and general acceptability scores of selected samples ranked blend 3 > blend 2 > blend 1. The in vitro protein digestibility values ranked blend 1 > blend 2 > blend 3. An increase of up to 9.5% units in the protein digestibility values was observed when compared to the nonextruded raw blends.     

球形芽孢杆菌S-腺苷甲硫氨酸合成酶基因的克隆、表达与活性鉴定

根据S-腺苷甲硫氨酸合成酶的保守性，利用苏云金芽孢杆菌（Bacillus thuringiensis）基因组中S-腺苷甲硫氨酸合成酶序列信息设计引物。以球形芽孢杆菌（Bacillus sphaericus, B.sph）基因组DNA为模版，扩增获得S-腺苷甲硫氨酸合成酶基因，酶解后插入大肠杆菌表达载体pGEX-6P-1，获得重组质粒pGEX-SAM。序列分析表明，来自球形芽孢杆菌的SAM合成酶在基因水平上与大肠杆菌（K02129），枯草芽孢杆菌（Z99129），酿酒酵母（U17246），小鼠（J05571），人（BC018359）的S-腺苷甲硫氨酸合成酶基因，分别有63.9%，75.4%，58.8%，59.1%，55.7%的同源性。由于一级结构存在明显的差异，我们将该重组的质粒转入大肠杆菌DH5α。通过亲和层析纯化出球形芽孢杆菌S-腺苷甲硫氨酸合成酶。用HPLC对S-腺苷甲硫氨酸合成酶的活性进行了分析。     

Use of cyclic voltammetry, photochemiluminescence, and spectrophotometric methods for the measurement of the antioxidant capacity of buckwheat sprouts

This paper describes the use of cyclic voltammetry, photochemiluminescence (PCL), and spectrophotometric methods (TEAC and FCR reducing capacity) for the measurement of the antioxidant capacity of dark- and light-grown buckwheat sprouts. Moreover, the flavonoid profile of studied material is provided. Methanol extracts (80%) from ungerminated buckwheat grain and 6 and 8 DAS (days after seeding) sprouts were used. The 8 day germination period was sufficient to obtain good quality sprouts with completely removed pericarps. The ungerminated buckwheat grain contained only rutin, whereas in sprouts produced in dark or light, a high level of isoorientin, orientin, vitexin, rutin, and isovitexin was found. The flavonoid content in sprouts produced under light was almost 2 times higher than those of sprouts produced in the dark. The antioxidant capacity of light-grown sprouts was higher than that of dark-grown ones. The results from voltammetric experiments obtained for buckwheat seeds and 6 and 8 DAS sprouts harvested under dark or light conditions highly correlated with those obtained by PCL antioxidant capacity of water-soluble substances (PCL ACW) (r = 0.99), PCL antioxidant capacity of lipid-soluble substances (r = 0.99), TEAC (r = 0.99), and FCR reducing capacity (r = 0.99). The use of cyclic voltammetry, PCL ACW, and TEAC was fully applicable for the evaluation of the antioxidant capacity of buckwheat sprouts.     

施肥量对旱作区藜麦生物性状及产量的影响

在平川区旱作区研究了不同施肥量对藜麦生物性状及产量的影响。结果表明,随着施氮量的增加,藜麦的株高、主穗长、生物产量、籽粒产量均得到了提高。尤其是施用藜麦专用肥(N-P2O5-K2O为13-22-10),籽粒产量达3 622.45 kg/hm2,与不施肥处理相比增产1 377.55 kg/hm2,增产率61.36%,效果明显。     

Physicochemical Properties of Common and Tartary Buckwheat Starch

Physicochemical properties of starch of three common (Fagopyrum esculentum) and three tartary (F. tataricum) buckwheat varieties from Shanxi Province, China, were compared. Starch color, especially b*, differed greatly between tartary (7.99–9.57) and common (1.97–2.42) buckwheat, indicating that removal of yellow pigments from tartary buckwheat flour may be problematic during starch isolation. Starch swelling volume in water of reference wheat starch (2.8% solids and 92.5°C) was 20.1 mL; for the three common buckwheat starches it was 27.4–28.0 mL; and for the three tartary buckwheat starches it was 26.5–30.8 mL. Peak gelatinization temperature (T_p) in water was 63.7°C for wheat starch, 66.3–68.8°C for common buckwheat and 68.8–70.8°C for tartary buckwheat. T_p of all samples was similarly delayed (by 4.0–4.8°C) by 1% NaCl. Enthalpy of gelatinization (ΔH) was higher for all six buckwheat starches than it was for wheat starch. However, one common buckwheat sample had significantly lower ΔH than the others. Starch pasting profiles, measured by a Rapid Visco-Analyzer, were characteristic and similar for all six buckwheat starches, and very different from the reference wheat starch. A comparison of pasting characteristics of common and tartary buckwheat starches to wheat starch indicated similar peak viscosity, higher hot paste viscosity, higher cool paste viscosity, smaller effect of NaCl on peak viscosity, and higher resistance to shear thinning. Texture profile analysis of starch gels showed significantly greater hardness for all buckwheat samples when compared to wheat starch.     

超高压处理改善苦荞淀粉理化性质及益生菌群落

为研究超高压(ultra-high pressure,HHP)处理对苦荞淀粉理化性质及功能性的影响,该文以6个不同压力处理后的苦荞淀粉为材料,利用扫描电镜、X射线衍射仪等分析了其淀粉颗粒大小、晶体结构、溶解度、透光率、冻融稳定性等特性,并通过建立体外模型模拟人体消化以及肠道发酵过程,利用气相色谱质谱联用技术和平板计数法,对小鼠粪便发酵液短链脂肪酸(short chain fatty acid、SCFAs)含量及主要菌群进行了测定。试验结果表明:超高压处理后苦荞淀粉颗粒出现凹陷与粘连状态,并逐渐失去原有形态,但其结晶类型仍为典型的A型,其结晶度在200 MPa时达到最大值41.8%;溶解度和膨胀度均随着压力的增加呈先减小后增大的趋势,并且其透光率会下降,其中在200 MPa时,溶解度和膨胀度都达到了最低0.83%和171%,而冻融稳定性会有一定的改善。此外,超高压处理后苦荞淀粉使肠道中双歧杆菌、乳酸杆菌的数量显著增加(P0.05),而大肠杆菌、肠球菌的生长受到显著抑制(P0.05)。同时,肠道内的pH值显著下降(P0.05),SCFAs中乙酸、丙酸、丁酸显著增加(P0.05),综上所述,超高压处理后苦荞可作为一种良好的天然改善肠道菌群的食物来源。