分散固相萃取—超高效液相色谱—四极杆/飞行时间质谱法测定禽肉中松香酸类物质

目的：建立超高效液相色谱—四极杆/飞行时间质谱法（UPLC-Q-TOF/MS）测定禽肉中松香酸类物质。方法：样品使用乙腈提取，盐析分层后，上清液由C₁₈固相萃取剂净化，UPLC-Q-TOF/MS电喷雾负离子模式测定。结果：3种松香酸类物质在10~500 μg/L质量浓度范围内线性关系良好，相关系数R²＞0.998，平均回收率为87.8%~98.5%，相对标准偏差（RSDs）为1.99%~6.71%（n=6）；方法检出限（LODs）为10 μg/kg，方法定量限（LOQs）为20 μg/kg。结论：试验方法操作简便，快捷，回收率和灵敏度高，精密度好，能够满足禽肉中3种松香酸类物质的检测需求。     

苎麻籽总黄酮含量测定方法比较研究

目的 比较苎麻籽总黄酮含量的测定方法。方法 以芦丁和槲皮素为对照品, 比较直接测定法、NaNO2-Al3+-NaOH法、AlCl3法3种比色方法下苎麻籽(70%乙醇提取液)的紫外-可见光谱图, 并通过精密度、稳定性、干扰试验、加标回收率试验对所选方法进行评价。结果 芦丁和槲皮素均不适合作为直接测定苎麻籽总黄酮的对照品; NaNO2-Al3+-NaOH法最大吸收波长为500 nm, 但受某些非黄酮类物质干扰, 使得该方法下的总黄酮含量测定值虚高; AlCl3法以芦丁为对照品, 测定波长为401 nm, 在0.004~0.02 mg/mL范围内浓度与吸光度值成良好的线性关系, 相关系数r2=0.9998, 该法受干扰小, 精密度高, 平均回收率为(99.46±4.16)%, 显色后在20~60 min内吸光值稳定。结论 AlCl3法简单可行, 适用于苎麻籽提取物中总黄酮含量的测定。     

大叶千斤拔黄酮类成分提取及抗氧化活性研究

通过单因素试验及响应面试验优化大叶千斤拔总黄酮的乙醇回流提取工艺条件,并对提取物的抗氧化活性进行评价。结果表明：优化后的提取工艺条件为提取时间52 min,料液比（m_{大叶千斤拔}∶V_乙醇）1∶6 （g/mL）,乙醇体积分数70%,提取温度60 ℃,该条件下提取物的总黄酮含量为75.47 μg/mg;提取物对ABTS⁺自由基、DPPH自由基清除能力的IC₅₀分别为0.044 9,0.212 3 mg/mL,总抗氧化能力及对Cu²⁺和Fe³⁺还原能力的IC₅₀分别为0.389 6,0.221 9,0.731 7 mg/mL。说明建立的最佳提取工艺可有效获取大叶千斤拔总黄酮成分;大叶千斤拔黄酮类物质具有较强的体外抗氧化活性。     

微咸水灌溉条件下施用不同改良剂对盐渍化土壤盐分离子分布的影响--测试文章

利用5种不同的土壤改良剂,对矿化度在2～3 g·L^-1的微咸水灌溉棉田土壤进行改良效果研究。结果表明：五种改良剂均降低土壤pH值和总盐含量,并能有效控制土体Na⁺、Ca²⁺、SO₄^2-、HCO₃^-积累;其中,磷石膏能显著降低土体Na⁺、Ca²⁺、SO₄^2-总含量（P＜0.05）,DS1997能显著降低土体Na⁺、HCO₃^-总含量（P＜0.05）,酸碱平衡剂显著降低土体Ca²⁺、SO₄^2-总含量（P＜0.05）,禾康改良剂有效控制土体SO₄^2-、HCO₃^-含量;改良剂对土体中Cl^-改良效果不显著（P＞0.05）。研究得出：微咸水灌溉导致土壤pH值升高和含盐量增加,造成土壤盐分的积累;土壤改良剂可有效减少微咸水灌溉引起的盐分积累,改善土壤理化特性和盐分离子分布。     

铁皮石斛茎、叶、花功能性成分、抗氧化活性及其相关性

目的：探索铁皮石斛茎、叶、花主要功能性成分的差异性、抗氧化能力大小及抗氧化活性的主要贡献成分。方法：以铁皮石斛茎、叶、花为试验材料,分别采用苯酚—硫酸法、NaNO₂-Al₃+NaOH法、福林酚法和酸性染料比色法对其多糖、总黄酮、总多酚和总生物碱含量进行测定比较,研究茎、叶、花的抗氧化能力,并通过相关性分析确定其主要抗氧化活性成分。结果：铁皮石斛茎、叶、花中均含有多糖、黄酮、多酚和生物碱类成分,但含量差异极显著（P<0.01）,其中多糖含量为茎（31.00%）＞叶（15.04%）＞花（8.11%）;总黄酮和总多酚含量均以花中最高,分别为2.133%和15.71%,叶中次之;总生物碱含量以花中最高,达0.022 3%,为茎中的近4倍;铁皮石斛茎、叶、花均具有较高抗氧化活性,且随着浓度的增大,其对DPPH自由基和ABTS自由基的清除能力逐渐增强,其中花的水提物和醇提物清除DPPH自由基和ABTS自由基的IC₅₀均最小,说明其氧化活性最大,较接近于维生素C的。相关性分析发现,铁皮石斛茎、叶、花抗氧化活性与总黄酮、总多酚和总生物碱含量呈正相关,与多糖含量无明显相关性,说明总黄酮和总多酚含量对铁皮石斛茎、叶、花的抗氧化活性贡献最大,总生物碱含量的贡献显著。结论：铁皮石斛叶和花同样具有广阔的应用价值和开发前景。     

杨梅提取物抑制二羰基化合物活性研究

目的 分离纯化杨梅果实提取物并考察不同组分对模型及饼干中甲基乙二醛(methylglyoxal, MGO)、乙二醛(glyoxal, GO)的抑制效果。方法 乙醇浸提制备杨梅果实粗提物(crude extract, CE),采用AB-8大孔吸附树脂,以不同体积分数的乙醇(20%、40%、60%)洗脱,得到三种杨梅提取物;采用NaNO₂- Al(NO₃)₃-NaOH比色法、pH示差法、液相色谱-质谱法测定提取物中花色苷、总黄酮含量和主要成分,并用气相色谱法考察其对模型和曲奇中MGO/GO的抑制活性。结果 40%乙醇组分F₁得率最高,活性最好,主要成分为矢车菊素-3-O-葡萄糖苷(cyanidin-3-O-glucoside, C-3-Glu)和杨梅素-3-O-鼠李糖苷(myricetin-3-O-rhamnoside, M-3-Rha);60%乙醇洗脱组分F₂成分主要为槲皮素-3-O-鼠李糖苷(quercetin-3-O-rhamnoside, Q-3-Rha);当曲奇中提取物添加量为0.4%时,F_1、F₂对MGO和GO均有抑制活性,其中F₁效果最佳,分别为61.5%和40.4%。结论 杨梅果实提取物具有良好清除MGO/GO的能力,为其作为添加剂应用于抑制食品加工中的MGO和GO提供了一定的理论基础。     

高效液相色谱法测定海带浓缩制品中岩藻黄素的含量

目的：建立高效液相色谱法测定海带浓缩制品中岩藻黄素含量测定方法。方法：采用Thermo BDS HYPERSIL C18 色谱柱,以1%的乙酸胺水溶液、甲醇、乙腈为流动相,流速 1.0 mL/min,柱温 30℃,检测波长 450 nm,进样量20μL,外标法定量；结果：在该条件下,岩藻黄素浓度在 0.999 ~9.987 μg/mL 范围内,与峰面积呈良好的线性关系 (R_⁼0.9999) ,平均加样回收率为98.53%,相对标准偏差(RSD)为 1.1%(n=9)。结论：本研究建立的含量测定方法简便、准确,重复性好,可用于海带浓缩制品的质量控制。     

粉葛愈伤组织不同极性提取物生物活性与功能成分分析

目的 为探究粉葛愈伤组织次生代谢产物的生物活性和功能成分。方法 采用系统溶剂法制备粉葛愈伤组织石油醚提取物(petroleum ether extract,PE)、乙酸乙酯提取物(ethyl acetate extract,EE)、甲醇提取物(methanol extract,ME)和水提取物(water extract,WE)等4种不同极性次生代谢产物,利用8株细菌、2个自由体系和1个细胞系测试四种提取物的抗菌、抗氧化和细胞毒活性,分析4种提取物中总黄酮、总酚、总多糖等主要功能成分含量与生物活性的相关性,并运用高效液相色谱法(high performance liquid chromatography,HPLC)检测其单体功能成分。结果 四种提取物的生物活性显著差异,其中EE对粪肠球菌、金黄色葡萄球菌、藤黄微球菌等革兰氏阳性菌作用突出,其最小抑菌浓度(minimum inhibitory concentration,MIC)为0.195~0.391 mg.mL_-1^,EE对1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)和2,2’-联氮双(3-乙基苯并噻唑啉-6-磺酸)二铵盐(2,2’-azinobis-(3-ethylbenzthiazoline-6-sulphonate),ABTS)自由基清除能力均最佳,其半抑制浓度(half maximal inhibitory concentration,IC₅₀)分别为0.2795和0.0640 mg.mL_-1^,EE对人肺癌细胞A549(human lung cancer cell)的抑制能力较佳,其半最大效应浓度(concentration for 50% of maximal effect,EC₅₀)为260.9 μg.mL_-1^{。总黄酮和总酚在}EE中含量均最高,分别为(273.89±7.48)μg.mg_-1^和(261.00±14.94)μg.mg_-1^,总多糖在WE中含量最高,达到(402.25±13.49)μg.mg_-1^,相关性分析显示,总黄酮为重要的抗菌和抗氧化活性成分。异黄酮单体功能成分在四种提取物中组成和含量差异均较大,且主要集中在EE和ME,其中EE以大豆苷(30.3428±1.4251)μg.mg_-1^{和大豆苷元}(45.7235±2.0230)μg.mg_-1^为主,ME以大豆苷(60.0125±3.9250)μg.mg_-1^{和染料木苷}(20.5655±1.3025)μg.mg_-1^为主。结论 粉葛愈伤组织次生代谢产物具有较强的抗菌、抗氧化活性以及微弱的细胞毒活性,主要含有大豆苷、染料木苷和大豆苷元等功能成分,该结果为粉葛愈伤组织次生代谢产物在食品与制药领域的开发利用提供了一定的参考。     

基于高倍富集放大反应的双点电位滴定法测定谷物中氟含量

【目的】饮食中氟可影响人体健康与安全,简捷准确检测饮食中氟含量就显得十分重要。【方法】以现有GB/T 5009. 18-2003的氟离子电极电位滴定法为基础,以高倍富集放大反应为获得高灵敏度的突破点,以双点电位滴定法为确保方法准确的手段,探寻出灵敏准确测定谷物中微量氟的新方法。以方法的检测限(LOD)、加标回收率和相对标准偏差(RSD)等为衡量指标,通过单因素试验法对影响富集反应的富集剂种类、用量、温度、时间、反应体系酸度(pH)、搅拌速率和洗涤次数等因素考察后,针对富集反应主要影响因素富集剂用量、反应温度、反应时间和反应体系酸度(pH)等用L₉(3^₄)正交试验优化获得最适宜的测定条件。【结果】所得最适宜条件为：含Ca^₂₊复合富集剂用量为(m_氟/m_复合剂) = 1:1×10^₅,反应时间200min,反应温度22℃,反应体系酸度pH 5.5,搅拌速率200~300 r/min,沉淀物洗涤4次。该法的LOD_F = 5.3×10^_-3 μg/g,且c_F在1.0×10^_-6 mol/L ~ 1.0×10^_-1 mol/L内呈良好定量函数关系：E = 38.657 lgc - 174.44 (R2 = 0.996)。加标回收率为91.5 %~100.3 %,测定结果较稳定(RSD≤2.7%)。实样氟含量测定值符合GB 2762-2005氟限量要求。【结论】本法集合了富集反应的高倍放大的效果和双点电位滴定法的高精准的特点,测定选择性高,速度快,灵敏度较高,是种实用可靠的微量氟的定量分析方法。且有易于实现自动化和智能化快捷在线检测的潜能。     

微波功率对月柿果片微波间歇干燥中水分迁移及品质的影响

目的：探讨微波间歇干燥对月柿果片水分动态和微观结构的影响。方法：选取不同微波功率（280,350,420,490,560 W）对月柿果片进行微波间歇干燥,对干燥过程中月柿果片的水分动态和迁移进行监测,以及对月柿果片的色泽、质构、微观结构进行测定分析。结果：新鲜月柿中的水分主要以结合水（T₂₁）、不易移动水（T₂₂）和自由水（T₂₃）3种形式存在,分别对应3个明显的水峰。随着干燥时间的延长,不易移动水和自由水的横向弛豫时间显著降低。L^*、a^*、b^*值随着微波功率的增加显著减小,ΔE、硬度、弹性、咀嚼性随着微波功率的增加而增加。随着微波功率的增加,果片的组织结构收缩塌陷越明显。结论：较低的微波功率能得到品质较佳的月柿干制品。     

含银杏叶提取物胶囊中黄酮类化合物检测方法改进

黄酮类化合物是银杏叶提取物中最重要的成分之一,采用亚硝酸钠—硝酸铝—氢氧化钠显色法测定保健食品中总黄酮含量存在一定缺陷。通过研究6种银杏叶提取物中主要的黄酮类组分对总黄酮含量的贡献值,结果表明槲皮苷是该方法下对总黄酮含量贡献最大的组分。进一步研究了该方法测定HZ胶囊(某公司生产的银杏叶提取物胶囊)中总黄酮含量过程中取样量、洗脱液乙醇浓度和超声时间对测定结果的影响,结果表明洗脱液乙醇浓度和超声时间对HZ胶囊中总黄酮含量具有重要影响。改进方法后,HZ胶囊中总黄酮含量在1.68~1.83g/100g,平均含量为1.71~1.77g/100g,相对标准偏差为1.36%~4.08%,芦丁回收率为94.05%~100.44%,重复性、精密度和加标回收率结果表明改进后的方法符合HZ胶囊生产过程用于质量控制的检测方法要求。     

Evaluation of Aluminium Complexation Reaction for Flavonoid Content Assay

Two widely applied spectrophotometric assays based on aluminium complex formation used for determination of total flavonoid content in food or medicinal plant samples were examined for several compounds from different classes of flavonoid family. The method which involves the measurement at 410–430 nm after addition of AlCl₃ solution is selective only for flavonols and flavones luteolin. The procedure in the presence of NaNO₂ in alkaline medium seems to be specific for rutin, luteolin and catechins, but also phenolic acids exhibit considerable absorbance at 510 nm. Application of both procedures to natural samples gave different order in terms of their flavonoid content. Thus, the expression “total flavonoid” content is not adequate as the results of both methods are dependent on the structure of the individual flavonoids present.     

Comparison of flavonoids profile in sprouts of common buckwheat cultivars and wild tartary buckwheat

In this study, major types of flavonoids in 7‐day sprouts of five common buckwheat cultivars grown in Poland (Hruszowska, Kora, Panda, Luba and Emka) and wild tartary buckwheat were investigated. Results demonstrated that sprouts of common buckwheat cultivars and wild tartary buckwheat contained both known and a newly discovered flavonol: quercetin 3‐O‐galactosyl‐rhamnoside. An exceptionally high content of this flavonoid was found in cotyledons of wild tartary buckwheat (30.79 ± 0.14 mg g^?1 DW), exceeding about 10 times level of rutin (3.16 ± 0.07 mg g^?1 DW). The results are not consistent with the data published so far on the content of flavonoids in sprouts of tartary buckwheat. Higher levels of flavonoids were measured in cotyledons than in hypocotyls with the exception of anthocyanins, which were present in higher amounts in hypocotyls. Cotyledons of common buckwheat sprouts were rich in C‐glycosides of luteolin and apigenin, the total content of which exceeded ca. 5 times the concentration of rutin.     

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.     

Antioxidant properties of tartary buckwheat extracts as affected by different thermal processing methods

The effects of roasting, pressured-steam heating and microwave heating on total phenolics, total flavonoids, and antioxidant properties of whole-meal flour from tartary buckwheat (Fagopyrum tataricum Gaertn.) were investigated. The total phenolics were evaluated by Folin-Ciocalteau assay, total flavonoids by aluminum nitrate colorimetric assay whilst antioxidant properties were based on free radical scavenging activity of flour extracts against hydroxyl and superoxide anion radicals, and inhibition of lipid peroxidation in vitro. This study showed that thermal treatment of buckwheat flour caused a decrease in total phenolics, total flavonoids and antioxidative activities. The changes in trend of the antioxidant activities due to the thermal treatment were positively correlated with the content of phenolics (R² = 0.8401-0.9909). Therefore, it can be suggested that special care should be taken when processing method is selected for the exploration of tartary buckwheat products.     

Composition and antioxidative properties of the flavonoid-rich fractions from tartary buckwheat grains

Tartary buckwheat, a healthy food, is associated with a reduced risk of certain human chronic diseases; however, its bioactive components are unknown. This study used high performance liquid chromatographyphotodiode array-mass spectroscopy (HPLC-PDA-MS) to identify the flavonoids in flavonoid-rich fractions (FRFs) from tartary buckwheat grain and tested antioxidative capacity of FRFs to confirm their bioactivity. Ultraviolet (UV) absorption and electrospray ionization (ESI⁻) MS/MS spectra identified several flavonols in the embryo, endosperm, testa, and hull, including the predominant flavonoid rutin and minor flavonoids quercetin 3-O-rutinoside-3′-O-β-glucopyranoside, kaempferol 3-O-rutinoside, and quercetin. Tartary buckwheat FRFs extended the Rancimat induction period of lard less than common buckwheat FRF did, while their scavenging rate of DPPH free radicals exceeded that of common buckwheat FRF and rutin. These results indicate that tartary buckwheat FRFs from the grains have potential health benefits.     

Nutritional composition and flavonoids content of flour from different buckwheat cultivars

Thirty nine buckwheat cultivars were collected from China, of which twenty one were tartary buckwheat and others were common buckwheat. Flour samples from these cultivars were analysed for colour properties, nutritional composition and flavonoid content. Buckwheat cultivars exhibited high variations for each of these parameters. The flour of common buckwheat showed a higher whiteness index than that of tartary buckwheat and contained very low levels of flavonoids. On average, the tartary buckwheat flour contained a higher level of ash (2.38%) and lower levels of total starch (70.22%), amylose (22.32%), resistant starch (17.66%) than the common buckwheat flour (2.17%, 73.69%, 23.01%, 18.69% respectively) (P < 0.05) whereas the contents of proteins, fats and crude fibres of the tartary buckwheat flour were similar to those of common buckwheat flour. The Mei‐Hua‐Shan tartary buckwheat flour contained the highest level of total flavonoids and quercetin (22.74 mg g^?1 and 2.38 mg g^?1, respectively).     

Buckwheat (Fagopyrum esculentum Moench) Grain and Fractions: Antioxidant Compounds and Activities

Abstract: Buckwheat (Fagopyrum esculentum Moench) is an alternative crop belonging to the Polygonaceae family. In comparison to antioxidant activity of frequently used cereals, buckwheat has been reported to possess higher antioxidant activity (AOA), mainly due to high rutin content. The objective of this work was to determine the main antioxidant compounds and AOA of buckwheat grain fractions (whole grain, hull, and groat). Buckwheat grain fractions were extracted with ethanol/water (80/20, v/v), followed by determination of total phenolic and flavonoid content. Quantification of phenolic compounds and tocopherols was performed by high‐performance liquid chromatography (HPLC). The AOA was estimated by 2 direct electron spin resonance (ESR) and 4 indirect (spectrophotometric) tests. Significantly higher contents of total phenolics and total flavonoids were found in buckwheat hull than in whole grain and groat. Protocatechuic, syringic, and sinapic acid, rutin, and quercetin were found in all tested fractions, whereas vanilic acid was found in whole grain and hull. The content of total tocopherols in investigated samples ranged from 23.3 mmol/g for hull to 61.8 mmol/g for groat. Hull was superior in scavenging activity on 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH^?), hydroxyl (^?OH), and superoxide anion (O₂^?‐) radicals, reducing activity, AOA by β‐carotene bleaching method, and chelating activity on Fe²⁺ as evidenced by its lower IC₅₀ value. Obtained results can broaden the utilization of buckwheat, especially a share of hull in whole grain flour production. Practical Application: Obtained results suggest possibility to supplement the whole grain buckwheat flour with hull, which leads toward better usage of by‐products in buckwheat production, and enhancement of antioxidant potential of the final product.     

苦荞麦中黄酮成分剖析

苦荞麦中富含黄酮,通过对苦荞麦中各部分黄酮的测定,结果发现,苦荞麦皮中黄酮含量较高。