壳聚糖对桑叶水提液的絮凝工艺研究

运用单因素实验和正交实验,以总黄酮和总多糖含量为指标,对壳聚糖加入量、桑叶水提液质量体积比、药液pH值及水浴温度进行考察,确定壳聚糖对桑叶水提液的最佳絮凝工艺条件为:桑叶水提液质量体积比1∶10(g∶mL)、壳聚糖加入量1.2 mL.g-1、药液pH值6.0、水浴温度35℃、絮凝时间3 h。在此条件下,所得总黄酮和总多糖平均含量分别提高至27.46 mg.mL-1、51.15 mg.mL-1。该方法成本低、生产周期短。     

分光光度法测定桑叶中黄酮总含量的研究

黄酮类物质是桑叶中主要的有效成分。对分光光度法测定桑叶中总黄酮含量进行了研究,采用芦丁为对照品,在508 nm处建立了工作曲线,并考察该方法的精密度和稳定性。实验结果表明:在检测浓度范围内,芦丁浓度与吸光度之间有良好的线性关系(r=0.99965);该方法具有较好的精密度(RSD=0.576%),但其稳定性差。     

桑叶蛋白的提取及应用分析

桑叶中蛋白质含量较高,氨基酸种类丰富,桑叶蛋白酶促水解产物具有抗氧化等功效。桑叶蛋白应用前景广阔,可应用于食品、保健品、医药等领域。介绍了桑叶蛋白的提取工艺,并对应用现状进行分析,为桑叶蛋白的进一步开发和利用提供参考。     

ZTC1＋1天然澄清剂在桑叶多糖提纯中的应用

考察Ⅱ型ZTC1＋1天然澄清剂在桑叶多糖提取中的提纯效果。以硫酸-蒽酮法测定多糖含量,通过正交试验优化天然澄清剂处理工艺。试验表明Ⅱ型ZTC1＋1天然澄清剂能有效地保留桑叶中的有效成分多糖。适宜工艺条件为药液浓缩程度为5mL／g,澄清剂B和A两组分的加入量分别为浓缩药液体积的2％和1％,絮凝温度50℃。在此工艺下,多糖保留率为96％,浸膏中多糖含量约为22％,蛋白去除率约为16％。     

从桑叶中提取多酚、黄酮和多糖的优化试验

研究了用水煮浸提法提取桑叶药用成分，并分别测定了浸提液中的多酚、黄酮和多糖等成分的含量。通过正交试验对提取工艺中的温度、料液比、浸提时间及酸碱度等因素进行优化，用综合评分法确定最佳提取条件，结果表明：在80℃，料液比1：100，pH=10，浸提60min，浸提液中多酚含量达9．56mg／g。黄酮含量达15．17mg／g，多糖含量达92．51mg／g。     

不同提取方法对桑叶中芦丁含量的影响研究

本实验阐述了不同方法对提取桑叶中芦丁含量的影响,通过线性关系实验、精密度实验、重复性试验、稳定性试验、加样回收率试验的检验,同时用水和90.00%乙醇对桑叶分别进行回流、超声和索氏提取的方式来考察不同提取方法对桑叶中芦丁含量提取的影响,其结果为以90.00%的乙醇回流提取1小时提取两次,芦丁提取率最大,所得桑叶中芦丁含量约为5.30%。     

干桑叶浸提物总还原力的化学应用研究

以干桑叶为实验材料,在相同色谱和质谱的条件下,对干桑叶浸提物的挥发性产物成分及含量等方面进行分析。以乙酸乙酯为溶剂,采用回流法得到桑叶乙酸乙酯浸提物(EAE),进行气相色谱-质谱(GC-MS)分析,共鉴定出33种化合物。以体积分数70%乙醇溶液为溶剂,采用超声波辅助浸提法得到桑叶70%乙醇超声浸提物(EUE),进行GC-MS分析,共鉴定出3种化合物。对EAE、EUE分别进行总还原力测定,实验浓度范围内两种浸提物均有较好的还原力,EUE的总还原力更强,EAE的总还原力则更加稳定。干桑叶浸提物具有在化工产品等方向的潜在开发价值。     

桑叶染色液的提取及贮存过程的变化

为解决桑叶作为天然植物染料源在工厂实用化中的一些问题进行了本研究。桑叶染色液既可用鲜桑叶也可用桑叶粉提取,用桑叶粉有利于工厂贮存和加工;桑叶粉可由桑叶经日晒粉碎、烘干粉碎得到,日晒式节约、方便,即有利于农户也有利于厂商;桑叶提取染色液为碱性、在阴凉的室温下避光可以保存一段时间,还原剂的加入可使保存时间延长;用20g/L的Na OH作为提取剂时,采用大浴比1∶100,一次性沸煮提取的方法较节约。     

养蚕区桑叶样品中的氟含量测定

介绍了运用氟离子选择电极法测定桑叶中的氟含量.方法的回归方程为y=63.2lgx-273.2,r=0.9996.通过对不同采样点样品的快速测定,及时了解桑叶中氟污染的现状,为管理部门能及时作出相应整治措施提供科学依据.     

桑叶活性成分的含量及其提取工艺研究进展

桑叶是一种十分重要的药食两用植物资源,其含有多种生物活性成分,在降血糖、降血压、抗氧化、抗菌、抗病毒和抑癌等方面具有一定功效,颇具开发价值。本文综述了近年来在桑叶中重要生物活性成分含量及其提取工艺的研究进展,以期为桑叶资源开发利用提供参考。     

Improvement of quality and antioxidant properties of dried mulberry leaves with combined far-infrared radiation and air convection in Thai tea process

Combined far-infrared radiation with hot-air convection (FIR-HA) drying was used for improving colour and antioxidant properties of mulberry leaf tea. Antioxidant properties and phenolic compounds of FIR-HA dried mulberry tea were determined and compared with the commercial product and with fresh leaves. We found that a smaller decrease in L and b values of the FIR-HA dried tea than those of commercial tea was observed. FIR-HA tea was found to have similar colour to fresh leaf while the commercial tea had darker colour. A significant decrease in total phenolic acid content (TPC) and total flavonoid content (TFC) was found in hot-air (HA) dried commercial tea compared to fresh leaves, while TPC in FIR-HA dried tea was significantly increased. Similar results were found in 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical activities. However, the results were different for ferric reducing antioxidant power (FRAP). Both teas had lower FRAP values compared to fresh leaves. Eleven phenolic compounds were identified in fresh leaf and in mulberry tea, namely p-coumaric acid, benzoic acid, (+)-catechin, chlorogenic acid, vanillic acid, syringic acid, sinapic acid, protocatechuic acid, ferulic acid, gallic acid and caffeic acid. The total content of phenolic compounds (TPCC) increased in FIR-HA dried samples compared to those of HA dried tea, except for chlorogenic and syringic acids, which were found in greater amounts in HA dried commercial tea. Our results have demonstrated that FIR-HA should be considered as a suitable drying method for mulberry tea with respect to preserving its antioxidant properties and phenolic compounds.     

Comparative Proteomic Analysis of Tolerant and Sensitive Varieties Reveals That Phenylpropanoid Biosynthesis Contributes to Salt Tolerance in Mulberry

Mulberry, an important woody tree, has strong tolerance to environmental stresses, including salinity, drought, and heavy metal stress. However, the current research on mulberry resistance focuses mainly on the selection of resistant resources and the determination of physiological indicators. In order to clarify the molecular mechanism of salt tolerance in mulberry, the physiological changes and proteomic profiles were comprehensively analyzed in salt-tolerant (Jisang3) and salt-sensitive (Guisangyou12) mulberry varieties. After salt treatment, the malondialdehyde (MDA) content and proline content were significantly increased compared to control, and the MDA and proline content in G12 was significantly lower than in Jisang3 under salt stress. The calcium content was significantly reduced in the salt-sensitive mulberry varieties Guisangyou12 (G12), while sodium content was significantly increased in both mulberry varieties. Although the Jisang3 is salt-tolerant, salt stress caused more reductions of photosynthetic rate in Jisang3 than Guisangyou12. Using tandem mass tags (TMT)-based proteomics, the changes of mulberry proteome levels were analyzed in salt-tolerant and salt-sensitive mulberry varieties under salt stress. Combined with GO and KEGG databases, the differentially expressed proteins were significantly enriched in the GO terms of amino acid transport and metabolism and posttranslational modification, protein turnover up-classified in Guisangyou12 while down-classified in Jisang3. Through the comparison of proteomic level, we identified the phenylpropanoid biosynthesis may play an important role in salt tolerance of mulberry. We clarified the molecular mechanism of mulberry salt tolerance, which is of great significance for the selection of excellent candidate genes for saline-alkali soil management and mulberry stress resistance genetic engineering.     

桑椹红色素提取试验

本试验从桑椹原浆中提取桑椹红色素 ,并对其理化性质开展研究。结果表明 ,在所采用工艺条件下 ,桑椹红色素浸膏得率 11% ;桑椹红色素属花青素类色素 ,在酸性条件下 ,对温度、光照和食品添加剂的影响 ,显现出较稳定的特征。还对桑椹红色素浸膏的营养成分作了测试分析     

正交试验法优选药用菊花的总黄酮提取工艺

采用超声提取的方法,通过正交试验确定杭菊、贡菊、野菊的最佳提取条件,比较其总黄酮的含量.实验结果表明,贡菊中的总黄酮含量最高,野菊其次,杭菊最低.它们的提取最佳条件如下:贡菊超声时间90 min、乙醇体积分数60%、液料比(mL∶g)45∶1;野菊超声时间90 min、乙醇体积分数45%、液料比(mL∶g)45∶1;杭菊超声时间90 min、乙醇体积分数45%、液料比(mL∶g)40∶1.在最佳提取条件下进行了4次验证实验,相对标准偏差在0.8%以下.     

气相色谱法测定桑叶中残杀威残留量

利用气相色谱仪,建立了残杀威在桑叶中残留量的分析方法。样品以乙腈提取,毛细管柱气相色谱法测定。残杀威标准曲线的线性范围为0.1～20mg·L-1,线性相关系数为0.9996,残杀威在桑叶中最低检测浓度为0.05mg·kg-1,平均回收率在81.23%～102.54%之间,变异系数为5.48%～6.42%,符合农药残留测定要求。     

Molecular Characterisation of Flavanone O-methylation in Eucalyptus

Flavonoids are ubiquitous polyphenolic compounds in plants, long recognised for their health-promoting properties in humans. Methylated flavonoids have received increasing attention due to the potential of methylation to enhance medicinal efficacy. Recently, Eucalyptus species with high levels of the O-methylated flavanone pinostrobin have been identified. Pinostrobin has potential commercial value due to its numerous pharmacological and functional food benefits. Little is known about the identity or mode of action of the enzymes involved in methylating flavanones. This study aimed to identify and characterise the methyltransferase(s) involved in the regiospecific methylation of pinostrobin in Eucalyptus and thereby add to our limited understanding of flavanone biosynthesis in plants. RNA-seq analysis of leaf tips enabled the isolation of a gene encoding a flavanone 7-O-methyltransferase (EnOMT1) in Eucalyptus. Biochemical characterisation of its in vitro activity revealed a range of substrates upon which EnOMT1 acts in a regiospecific manner. Comparison to a homologous sequence from a Eucalyptus species lacking O-methylated flavonoids identified critical catalytic amino acid residues within EnOMT1 responsible for its activity. This detailed molecular characterisation identified a methyltransferase responsible for chemical ornamentation of the core flavanone structure of pinocembrin and helps shed light on the mechanism of flavanone biosynthesis in Eucalyptus.     

含高价锰叶面肥中钾含量的测定

采用四苯硼酸钾重量法测含高价锰叶面肥的钾含量,以硫酸锰作催化剂,在碱性条件下消除高价锰对钾测定的干扰。