电感耦合等离子体质谱(ICP-MS)法同时测定荞麦秸秆中的8种重金属元素

基于硝酸-盐酸-氢氟酸消解体系,建立了马弗炉-微波消解-电感耦合离子体质谱(ICP-MS)法同时测定荞麦秸秆中的Cr、Cu、Ag、Mn、Fe、As、Ni、Pb等重金属含量测定方法。在微波消解的过程中,分别考察5种不同组合的混合酸体系及两种消解方法对荞麦秸秆中8种重金属测试结果的影响。实验结果表明,浓硝酸-浓盐酸-氢氟酸(6∶2∶2)混酸体系和马弗炉-微波消解样品前处理优于其他方法。在优化条件下,8种重金属加标回收率为91.2%~102%,相对标准偏差(RSD,n=5)为0.22%~4.7%,检出限为0.18~9.41μg/L。方法操作简便、快速、准确,结果可靠,能同时测定荞麦秸秆中8种重金属元素。     

加压溶剂萃取-气相色谱法测定荞麦中残留的有机氯农药

用所研制的24位全自动加压溶剂萃取仪(APLE),以丙酮-正己烷(体积比为1∶1)为溶剂,在100 ℃和10 MPa条件下,对荞麦样品中残留的7种有机氯农药进行了萃取,并通过气相色谱对萃取液进行定量分析。萃取的绝对回收率为68%～126%,相对标准偏差为1.2% ～14.7%,检测下限为0.051～0.18 ng/g。与索氏提取法对比,相对提取回收率为116%～148%,表明萃取收率高于索氏提取法。     

Buckwheat Hull-Enriched Pasta: Physicochemical and Sensory Properties

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

苦荞茶对水溶液中铅、铜、镉、锌、铬离子吸附作用的研究

生物吸附法以其材料易得、吸附效果好、易解析、环境友好等优点而被广泛的应用于水溶液中低浓度重金属离子的吸附去除。光谱学显示苦荞茶含有多种基团且表面结构疏松，对水溶液中金属离子具有一定吸附潜力。探讨苦荞茶对水溶液中铅、铜、镉、锌、铬离子吸附作用光谱分析。采用扫描电镜(SEM)、能谱分析(EDS)、傅里叶红外光谱(FTIR)对苦荞茶吸附铅、铜、镉、锌、铬前后进行表征，初步解析苦荞茶对水溶液中铅、铜、镉、锌、铬离子吸附作用。使用等温吸附方程(Langmuir，Freundlich，Temkin和Dubinin-Radushkevich) 与动力学方程(准一级、准二级和颗粒内扩散)来评价苦荞茶对水溶液中铅、铜、镉、锌、铬离子吸附方式及行为。响应面法是一种数学建模的优化方法，能回归拟合各因素与实验结果之间的函数关系，从而确定实验因素及其交互作用对目标值的影响程度。采用响应面法考察目标离子初始浓度(A)、吸附剂颗粒大小(B)、吸附剂投加量(C)和吸附时间(D)四个因素对苦荞茶吸附水溶液中铅、铜、镉、锌、铬离子能力的影响作用及程度。等温吸附方程显示，苦荞茶对水溶液中铅、铜、镉、锌、铬离子吸附方式以多层吸附方式为主，伴有其他吸附类型，苦荞茶对目标重金属吸附量排序为：铅＞镉＞铜＞锌＞铬，即为：30.67＞16.18＞13.85＞10.81＞8.43 mg·g-1。动力学方程与苦荞茶扫描电镜(SEM)提示，苦荞茶对水溶液中铅、铜、镉、锌、铬离子吸附过程符合准二级动力学，其吸附速率由液膜扩散和颗粒内扩散作用共同控制，而且苦荞茶表面疏松的结构出现表面趋于平滑，孔洞出现融合的现象。能谱分析(EDS)与傅里叶红外光谱(FTIR)证实了水溶液中铅、铜、镉、锌、铬离子被苦荞茶所吸附，苦荞茶中-OH，-CH₂，-CH₃，CO， -NH，-C-O，CH基团参与水溶液中铅、铜、镉、锌、镉离子结合吸附作用并存在同一类型的基团吸附结合不同目标离子的现象。响应面法构建考察因素影响苦荞茶对水溶液中铅、铜、镉、锌、铬离子去除能力模型，其调整回归决定系数分别为Adj R2_Pb=97.10，Adj R2_Cu=98.44，Adj R2_Cd=94.55，Adj R2_Zn=92.71，Adj R2_Cr=97.02，说明非线性模型可用来评价考察因素对苦荞茶吸附水溶液中铅、铜、镉、锌、铬离子影响作用。响应面法分析表明，考察因素[离子初始浓度(A)、吸附剂颗粒大小(B)、吸附剂投加量(C)和吸附时间(D)]对铅、铜、镉、锌、铬离子去除率影响作用大小排序为：铅离子(A＞D＞B＞C)、铜离子(A＞C＞D＞B)、镉离子(A＞B＞C＞D)、锌离子(B＞C＞A＞D)、铬离子(C＞B＞D＞A)。研究结果说明，苦荞茶对水溶液中铅、铜、镉、锌、铬离子具有良好的吸附作用，为苦荞茶拓展新的应用途径提供了参考依据。     

Effects of Airflow Ultrafine-Grinding on the Physicochemical Characteristics of Tartary Buckwheat Powder

Five different ultrafine milled flours (UMFs) were prepared from Tartary buckwheat via airflow ultrafine-grinding at different grinding pressures. The airflow ultrafine-grinding resulted in marked differences in particle size (from 100 to 10 μm). The UMFs were all brighter in appearance (higher L*) than Tartary buckwheat common flour (TBCF). Illustrated by the example of 70 °C, the UMFs were also found to have a greater water holding capacity (from 4.42 g/g to 5.24 g/g), water solubility (from 12.57% to 14.10%), and water solubility index (from 5.11% to 6.10%). Moreover, as the particle sizes reduced, the moisture content decreased (from 10.05 g/100 g DW to 7.66 g/100 g DW), as did the total starch content (from 68.88 g/100 g DW to 58.24 g/100 g DW) and the protein content (from 13.16% to 12.04%). However, the grinding process was also found to have negative effects on the mineral content of the Tartary buckwheat. Additionally, several substantial variations were found in their hydration properties along with grinding pressure changes in the differently ground UMFs. Consequently, fine Tartary buckwheat powders of a bright yellow color, with superior food processing properties, were prepared in this study by airflow ultrafine-grinding.     

低氮胁迫下苦荞根际土壤纤维素酶活性的响应机制：荧光光谱法测定

土壤纤维素酶参与土壤中养分的循环过程,分解纤维素为小分子糖分微生物生命活动提供能源物质,并且对生态系统有重要的指示作用。如何快速、精确的测定纤维素酶活性对土壤生态系统诊断、恢复等有重要指示意义。自然界中不同的氮肥处理及种植不同的苦荞品种均会对土壤纤维素酶活性产生影响。利用德国进口全自动进样酶标仪(InfiniteR 200 PRO),以4-Methylumbelliferyl β-D-cellobiopyranoside (Cel) 纤维素荧光物质为底物,将不同耐瘠性苦荞(迪庆苦荞-耐低氮;黑丰1号-不耐低氮)根际土壤以悬液形式用排枪吸取微量和荧光底物混合加入到96孔微孔板进行充分反映、培养测定土壤中纤维素酶活性,其中将对照板和样品放在同一个板块上,减少培养空间占用和操作时间。结果表明,除了苦荞成熟期的常氮处理,苗期和开花期的低氮处理条件下,纤维素酶活性均表现为迪庆苦荞根际土壤显著高于黑丰1号,迪庆根际纤维素酶活性在苗期低氮处理下高于黑丰39.50%;纤维素酶活性在迪庆苦荞的开花期和成熟期氮处理间有显著性差异,表现为常氮高于其他处理,而黑丰1号仅在开花期时常氮处理和其他处理之间有显著差异;灭菌处理酶活性显著低于常氮处理的54.29%,说明迪庆苦荞根际纤维素酶一部分来源于微生物的贡献,养分充足时微生物的活性更高,贡献越大。荧光光谱法分析出的纤维素酶活性表明耐瘠性品种迪庆苦荞可以通过增加根际土壤酶活性的方法来抵抗外界环境的胁迫,面对黄土高原养分贫瘠的土壤,可以考虑选种耐贫瘠的品种来降低成本增加收益。试验过程中,荧光标记的酶标仪测定方法与传统的测定方法相比更加快捷、准确和节约,同样适合大批量样品测定,可以为未来精准农业生产,测土配方施肥提供及时的数据支持。     

Suppressive activity of protease inhibitors from buckwheat seeds against human T-acute lymphoblastic leukemia cell lines

The buckwheat protease inhibitor designated BWI-1, a member of the potato inhibitor I family, inhibits trypsin, chymotrypsin, and subtilisin, whereas the buckwheat protease inhibitor designated BWI-2a, a novel protease inhibitor homologous to the vicilin family, inhibits only trypsin. We examined the suppressive activity of BWI-1 and BWI-2a against T-acute lymphoblastic leukemia (T-ALL) cells, such as JURKAT and CCRF-CEM, and human normal blood lymphocytes. Both inhibitors significantly suppressed the growth of T-ALL cells as judged by the soluble 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (tetrazolium/formazan assay). JURKAT cells showed slightly higher susceptibility to buckwheat inhibitors than CCRF-CEM cells. Modification of Arg residue(s) in inhibitors by 1,2-cyclohexandione inactivated their trypsin inhibitory activity, considerably abolishing their suppressive activity. This suggests that the trypsin inhibitory activity is involved in the suppression of growth of human T-ALL cell lines. It was further found that both inhibitors triggered programmed cell death (apoptosis) of these cell strains with DNA fragmentation.     

Guidelines for buckwheat enriched bread

Thermal analysis was used to check the role of the main components of buckwheat flour (polysaccharides and proteins) to assess guidelines for novel recipes for bread from wheat and buckwheat flour blends with improved nutritional properties. The structure-related poor protein quality, namely, the lack of network-forming links, severely limits the use of buckwheat flours in bread-making. Data from TG and DSC analysis indicate that the introduction of a de-hulling step in the buckwheat milling diagram and the addition of some buckwheat polysaccharide fractions, isolated from the buckwheat husk, that contribute to the formation of the crumb structure thanks to their effect on the phase separation driven by the thermodynamic incompatibility with wheat gluten proteins, allows one to tune opposite effects and obtain bread from de-hulled buckweat/wheat flour blends with alveolar distribution much close that of the wheat bread.     

黑苦荞保健茶中重金属的分析评价

采用原子吸收光谱法和原子荧光光度法测定了四川省凉山州某几个品牌黑苦荞保健茶中的重金属铅、镉、铬、无机砷和汞的含量,并以NY/T 1510-2007标准绿色食品麦类制品为依据,对黑苦荞保健茶重金属污染状况进行了分析评价。结果表明,黑苦荞保健茶受重金属元素污染的程度由高到低表现为铅、铬、镉、无机砷和汞,但含量均未超过国家标准规定;黑苦荞叶芽茶和全株茶的重金属污染较为严重,全胚茶未受重金属污染。