Separation and identification of polyphenols in apple pomace by high-speed counter-current chromatography and high-performance liquid chromatography coupled with mass spectrometry

Apple pomace, a by-product in the processing of apple juice, was investigated as a potential source of polyphenols. Two methods of separation and purification of polyphenols from apple pomace extract were established by combination of gel chromatography with high-speed counter-current chromatography (HSCCC) and solvent extraction with HSCCC, respectively. The optimal separation was performed on a Sephadex LH-20 column using gradient aqueous ethanol as eluting solvent from 0% to 100% in increments of 10%. HPLC analysis indicated that main polyphenols existed in fractions eluted between 40% and 50% aqueous ethanol. The fractions of interest from column were separated by HSCCC with the solvent system hexane–ethyl acetate–1% aqueous acetic acid (0.5:9.5:10, v/v/v). Ethyl acetate fractionation of the apple pomace extract followed by direct HSCCC separation by the same solvent system in the volume ratio of 1:9:10 also produced a good separation of the main polyphenols of interest. Six high-purity polyphenols were achieved tentatively and identified by HPLC/MS: chlorogenic acid (1, m/z 354), quercetin-3-glucoside/quercetin-3-glacaside (2, m/z 464), quercetin-3-xyloside (3, m/z 434), phloridzin (4, m/z 436), quercetin-3-arabinoside (5, m/z 434), and quercetin-3-rhamnoside (6, m/z 448). These results provided a preliminary foundation for further development and exploration of apple pomace.     

高效液相色谱法测定苹果汁中8种酚类化合物

提出了高效液相色谱法同时测定苹果汁中儿茶素、绿原酸、咖啡酸、表儿茶素、香豆酸、阿魏酸、槲皮素和根皮素等8种酚类化合物的方法,并考察了光照、保存时间等因素对酚类化合物的稳定性的影响.选用Eclipse XDB C18色谱柱(150 mm×4.6mm,5μm),以甲醇和乙酸-水(1+99)溶液作为流动相进行梯度洗脱,利用二极管阵列检测器,在各种酚类物质的最大吸收波长下进行紫外光度检测.对各化合物工作曲线的线性范围作了试验,并推导得到相应的线性回归方程,其相关系数均为0.999 9,在苹果汁样品的基础上用标准加入法各进行7次测定,测得平均回收率均在96.0%～100.8%之间,相对标准偏差(n=7)小于等于3.0%,8种化合物的检出限(3S/N)分别为20,10,4,20,5,8,30和7μg·L-1.     

氢化物发生原子荧光光谱法测定磷酸中的砷

采用HCl处理H3PO4试样，氢化物发生原于荧光光谱法测定As，对仪器条件、HCl酸度、预还原剂用量、还原剂用量、共存干扰进行了试验，方法的检出限为0．18ng／mL，测定精密度1．9％-3．0％，回收率为96．0％-98．0％。     

Volatile constituents of Custard Apple

Summary Volatile components in Custard Apple (Annona atemoya) have been isolated by both trapping on Tenax GC followed by thermal desorption and by simultaneous distillation extraction (SDE). Analysis by capillary gas chromatography-mass spectrometry led to the characterisation of 40 components. Twenty components were identified in the headspace sample, and 94% of the GC peak area consisted of esters. The major components were methyl and ethyl butanoate and methyl hexanoate. All 25 components detected in the SDE extract were terpenes, major components being α- and β-pinene, E-ocimene and germacrene-D.     

超高效合相色谱-四极杆飞行时间质谱法测定水果和茶叶中手性农药顺式-氟环唑对映体残留

利用超高效合相色谱-四极杆飞行时间质谱( UPC2-QTOF/MS),建立了顺式-氟环唑在苹果、葡萄和茶叶中的手性对映体拆分与残留分析方法。对合相色谱条件(流动相改性剂及比例、色谱柱温度、背压、辅助溶剂等)进行了优化。样品采用乙腈提取, Cleanert TPT或Pesti-Carb柱净化, Chromega Chrial CCA柱进行分离,以CO2/异丙醇(95：5, V/V)为流动相,流速2.0 mL/min,动态背压13.79 MPa,柱温30℃,离子化辅助溶剂为2 mmol/L甲酸铵的甲醇-水(1：1, V/V),采用超高效合相色谱-四极杆飞行时间质谱分析测定,基质外标法定量。结果表明,本方法的线性范围为0.01 mg/L ~1.00 mg/L,相关系数大于0.99;在0.005,0.025和0.25 mg/kg添加浓度水平下,苹果和葡萄中顺式-氟环唑手性对映体平均回收率(n=6)为67.9%~92.8%,相对标准偏差小于10%,方法定量限为0.005 mg/kg;在0.01,0.05和0.5 mg/kg添加浓度水平下,茶叶中顺式-氟环唑手性对映体平均回收率( n=6)为74.1%~84.0%,相对标准偏差小于8%,方法定量限为0.01 mg/kg。本方法准确、简便、可靠,可以满足残留分析的要求。     

The influence of immersion and contact ultrasound treatment on selected properties of the apple tissue

Ultrasound (US) treatment is considered to be one of the most promising non-thermal technology used in the food processing. The food-related applications of this technique are linked to the analytical and technological purposes. The ultrasound waves in the food can cause the formation of micro-channels due to the systematic and alternating compression and decompression of the material (so called “sponge effect”). Additionally, in liquids the ultrasound application can cause the cavitation which can modify the food properties as well. Hence, due to its mechanism, the ultrasound treatment can also improve the extraction of pigments, aromas or antioxidants from the food matrices.     

基于高光谱成像技术和MNF检测苹果的轻微损伤

苹果损伤是一种发生在水果采摘和产后处理阶段的不可避免的主要缺陷。为了快速有效地识别苹果的轻微损伤,以具有代表性的双色红富士苹果为研究对象,提出了一种以高光谱成像和最低噪声分离(MNF)变换的苹果轻微损伤识别检测方法。首先,使用高光谱成像系统获取苹果的可见-近红外波段(400~1 000 nm)的图像,对比发现全波段的最低噪声分离变换比主成分分析(PCA)变换可获得更好的识别效果;其次,利用I-RELIEF算法对正常表皮和损伤区域的光谱进行分析得出权值系数图,依据该系数曲线挑选出了5个特征波段(560,660,720,820和960 nm);最后,特征波段和最低噪声分离变换开发了损伤苹果的识别检测算法。利用该算法对80个正常苹果和含有不同时间阶段轻微损伤的苹果进行试验,损伤识别总体正确率为97.1%,试验结果表明,利用该方法和选取的特征波段可以快速有效地识别苹果的早期轻微损伤,为利用多光谱成像技术和最低噪声分离变换在线检测苹果轻微损伤奠定了基础。     

苹果汁中吡虫啉农药残留荧光检测研究

根据有机物受激发射荧光的基本原理,研究了杀虫剂吡虫啉的荧光特性。利用荧光光谱仪对吡虫啉及苹果汁-吡虫啉混合体系进行了研究,得到了苹果汁中不同农药含量下的荧光谱图,分析了荧光强度与农药含量的关系。实验表明：当234 nm作为激发波长时,苹果果汁几乎没有荧光峰出现,而吡虫啉有很强的荧光,荧光峰值在373 nm左右。向果汁中逐量添加吡虫啉药液后,得到苹果汁中吡虫啉含量最佳预测模型,决定系数达到0.996 74,预测准确率高于90%。研究结果表明,利用荧光光谱法直接对苹果果汁中农药残留检测是快速和可行有效的。     

基于模糊识别的苹果花期冠层钾素含量高光谱估测

依据2008年和2009年2年在栖霞试验区利用地物光谱仪ASD FieldSpec3测定的苹果花期冠层高光谱和实验室内测定的钾素含量数据,以冠层高光谱反射率及其11变换形式与钾素含量分别进行相关分析,以相关系数最大者为自变量,采用模糊识别算法,建立钾素含量估测模型;以2008年的检验样本对模型进行检验,并利用2009的独立试验数据对模型进行验证。结果表明,原始光谱反射率(R)及其倒数(1/R)、对数(lgR)、平方根(R1/2)与钾素含量的相关性较差,但它们的一阶微分和二阶微分与钾素含量之间的相关性明显增强;建立的钾素含量估测模型=11.344 5h+1.309 7的相关系数r为0.985 1,总均方根差RMSE为0.355 7,F统计量为3 085.6;24个检验样本实测值与估测值的平均相对误差为9.8%,估测精度为90.2%;2009年试验验证精度达到了83.3%。表明模型用于苹果花期冠层钾素含量的估测具有较高的稳定性,模型精度能满足生产上对苹果钾素含量估测的要求。     

微区X射线荧光光谱仪研制及元素生物地球化学动态分布过程研究

微区无损分析可提供物质组成元素的原位分布信息,以揭示物质形成条件、元素动态分布过程与相互作用机理、生物代谢作用等。文章报道了实验室型微区X射线荧光(μXRF)光谱仪的研发和元素生物地球化学动态分布过程研究结果。μXRF光谱仪采用15 μm光斑的聚束毛细管X射线透镜为激发源,选用分辨率为135 eV的硅漂移探测器(SDD),样品和探测器间角度可调,使之可进行异型样品如地质样品的原位分析,利用五轴自控实现样品时空四维元素分布测定。利用该μXRF光谱仪测定了矿物-生物膜间的元素迁移和玉米种发芽过程中的元素分布,发现(1)生物膜可吸附、富集毒性元素铅,是重金属的重要汇集地,最大富集系数1.7。(2)生物膜是金属从固态矿物相经水相进入生态系统的重要途径。(3)在玉米种子中,可检测到K,Ca,Mn,Fe,Cu,Zn和Pb。Zn主要在胚乳中分布,胚中有少量Zn存在;在胚乳和胚中存在微量Fe;胚乳中存在微量Pb,胚中未观测到Pb。(4)经含Pb溶液浸泡发芽后,K在玉米种中胚和胚乳中部分富集,Fe分布在种皮和胚乳中,Cu和Zn主要在胚乳中分布;Pb主要在胚根、胚轴和胚芽中分布,且Pb在新生根中高度富集。研究表明,在种子萌发阶段,Pb等毒性元素可被植物滞留于根部,制约了其向地上部的转移,从而揭示了植物对毒性元素的耐受机制。