基于响应面分析法对烟叶中果胶测定方法的优化

为了对酶解-连续流动法测定烟叶中果胶含量的方法进行优化,采用Box-Benhnken实验设计及响应面分析法对酶解过程中的酶解温度、酶解时间和缓冲液pH值进行优化。结果显示,酶解温度对果胶测定影响最大,缓冲液pH次之,酶解时间影响最小,且最优酶解条件为酶解时间1.9 h、酶解温度56 ℃、缓冲液pH 3.8;在此条件下,果胶具有良好的线性关系(R²=0.999),加标回收率在99.2%~100.9%,相对标准偏差RSD(n=6)<3%;说明Box-Behnken设计结合响应面分析法优化所得的果胶测定方法具有较好的精密度及准确度,适用于烟叶中果胶含量的批量测定。     

流动分析法测定烟草中的纤维素

建立了测定烟草中纤维素含量的流动分析法。采用纤维素酶酶解烟草中的纤维素,利用流动分析仪测定水解液中的葡萄糖。结果表明:①最优酶解条件为:烟粉0.25 g,缓冲溶液60 mL,酶用量0.25 g,水解温度37℃,水解时间24 h;②方法的相对标准偏差(RSD)为2.40%,回收率为96.7%～103.8%,检测限为0.11 mg/mL。该方法适合于烟草中纤维素含量的测定。     

柠檬酸-纤维素酶法提取塔罗科血橙皮中的果胶

以塔罗科血橙皮为原料,采用柠檬酸-纤维素酶法提取了其中的果胶。探索了料液比、酶用量、酶解时间、酶解p H、酶解温度、酸提取p H、提取温度、提取时间等因素对果胶产率的影响。以正交优化建立了纤维素酶法提取果胶的最优条件:料液比为1︰40(g/m L)、酶用量为9 U/m L、酶解时间为45 min、酶解温度为35℃。在最优提取条件下果胶产率29.97%,总半乳糖醛酸含量为79.77%,酯化度为72.29%,含水率为8.37%。研究结果对塔罗科血橙废弃物的综合利用具有一定的参考意义。     

纤维素酶促进菠萝皮果胶提取的研究

为了促进菠萝皮中果胶的提取,采用了纤维素酶处理菠萝皮的酸解液,对此工艺条件进行了初步研究。通过实验,确定了最佳的酶解工艺条件:酶解温度为55℃,酶解pH为pH 4.2,纤维素酶的适宜用量为15.5 U/ml,酶解时间为140min。在此条件下,酶解液中果胶含量达到7.4g/L,比菠萝皮酸解液的果胶含量提高了40.7%。     

酶解-流动分析法测定烟草中果胶前处理方法的改进

为提高烟草中果胶的分析速度,对酶解流动分析法中烟叶的前处理过程进行了改进,即用5%醋酸溶液萃取代替80%乙醇溶液回流抽提除去烟末中的水溶性糖,并采用两种方法同时测定了20个烤烟烟叶样品中的果胶含量.结果表明:①改进法果胶的回收率为99.5%～105.7%,变异系数2.08%;②改进法的检测结果稍高于原方法,但二者没有显著性差异.     

不同成熟度杏果实发酵杏果酒品质分析

对新疆不同成熟度赛买提杏果实发酵的杏果酒理化性质和感官评价进行分析研究。结果表明：不同成熟度赛买提杏果实经酶解后的原果胶、果胶含量及酒精发酵后果酒中还原糖含量、总酸含量、pH 值、色度、色调、甲醇含量均有明显变化。青熟期杏果实经酶解后原果胶含量0.82%、可溶性果胶含量0.27%,发酵后杏果酒甲醇含量271.796 mg/L、酒精度10.57%vol、总酸含量13.6 g/L,酒体颜色呈黄褐色且口感伴有清爽的酸涩。完熟期杏果实经酶解后含原果胶1.04%、可溶性果胶0.55%,发酵后杏果酒甲醇含量为157.69 mg/L、酒精度为12.09%vol、总酸含量为11.98 g/L,酒体口感较为丰富,颜色呈浅金黄色,杏果实风味十足并具有典型性。因此,选择完熟期杏果实酿造的杏果酒有利于发酵过程控制和改善赛买提杏果酒品质。     

不同提取方法对黄秋葵果胶含量和结构特性的影响

本研究探讨了酸水热提、酶解、超声及酶解-超声四种提取方法对黄秋葵果胶含量及其结构特性的影响。酸水热提及酶解-超声联合法对黄秋葵果胶提取效果优于酶解和超声法;当干秋葵加入20倍pH 3 HCl水溶液,以70℃浸提1h(酸水热提法)或添加3‰果胶酶、50℃酶解90min后置于200W超声波处理10min(酶解-超声法)时,其果胶平均含量(以半乳糖醛酸质量分数计)达到43.61g/kg及32.59g/kg。四种提取方法所制果胶均为吡喃糖构型,但酸水热提及酶解法制备果胶的酯键易发生降解,其在1725cm~(-1)红外吸收峰有变弱甚至消失趋势;而超声或酶解-超声法处理则促进了果胶分子链断裂,其平均分子量由酸水热提法下533ku分别降至420～467ku、319ku。研究结果表明:采用酸水热提法(pH 3、70℃)制备黄秋葵果胶,其果胶得率高、分子量分布集中、外观呈片状且排列致密。本研究结果为高品质秋葵果胶的制备奠定基础。     

南瓜果胶不同提取方法的研究

以南瓜果肉为材料,采用咔唑比色的方法,通过正交试验,分别研究超声波法、纤维素酶法和离子交换树脂法提取南瓜果胶的最佳提取条件。结果表明：超声波法的最佳提取工艺条件为：超声波功率400W,时间35min,液料比10:1(ml/g),果胶得率5.98%;纤维素酶法提取果胶的最佳工艺条件为：酶解时间2.0h,pH4.5,酶解温度55℃,加酶量0.5%,果胶得率9.56%;离子交换树脂法提取果胶的最佳工艺条件为：树脂用量15%,料液比为1:20(g/ml),pH2.5,时间2.0h,温度80℃,果胶得率7.62%。三种提取方法进行比较,纤维素酶法果胶得率最高,为南瓜果胶的最佳提取工艺。     

山楂原液果胶酶解工艺

为改良山楂原液果胶的酶解效果,以山楂原液果胶脱除率为响应值,从四种商品酶中筛选出果胶去除率最高的Pectinex Yield MASH果胶酶。在单因素试验的基础上,对加酶量、酶解时间、酶解温度三个影响因素进行响应面优化。结果表明:山楂原液果胶最佳酶解工艺为加酶量12 U、酶解时间52 min、酶解温度45℃,在此条件下的果胶脱除率实际测定值为90.58%,与理论预测值90.18%接近,为山楂及其他水果高附加值产品生产工艺中果胶的脱除方法提供了科学的理论依据。     

再造烟叶中果胶降解条件优化及其应用研究

为降低造纸法再造烟叶中的果胶质含量(质量分数),以造纸法再造烟叶工艺生产线上经解纤和浸提处理的梗末混合物为研究对象,通过单因素及正交试验对黑曲霉产果胶酶降解的果胶工艺条件进行优化;采用在线裂解—气相色谱/质谱法(PY—GC/MS)对酶解前后样品的热裂解产物进行分析,采用硅烷化—GC/MS法分析果胶质酶解前后的单糖组成,并将处理前后的样品添加至卷烟中进行感官评价。结果表明:果胶降解最佳反应条件为酶活力3 700U/mL、料液比1∶1(m∶V)、酶解温度50℃、酶解时间1.5h,在该条件下果胶质降解率为32.47%;酶解后,样品果胶单糖组成中葡萄糖及半乳糖醛酸的含量降低。样品裂解产物的组成及含量有明显变化,酚类物质总量由(3.00±0.16)%降低至(2.46±0.11)%,醛酮类、醇类香味物质总量也有所降低,但杂环类、酯类香味物质总量增加;将酶解后的样品添加于卷烟后,卷烟烟气变得柔和,透发性好,刺激性降低,余味纯净舒适,但香气量及劲头略有不足。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press