核磁共振技术研究冷冻处理对魔芋粉丝中水分的影响

利用核磁共振技术测定魔芋粉丝在不同处理温度过程中质子的自旋-自旋弛豫时间(T2)以及质子信号密度(A)。魔芋粉丝体系中水分流动性不同,T2和A不同。结果表明,在魔芋粉丝冷冻处理过程中,其“束缚水”和“自由水”迁移行为不同。当处理温度为－12℃,处理时间为3h时,复水后的魔芋粉丝持水性质最佳。     

绿豆淀粉魔芋凝胶基体的制备及性能表征

为改善纯魔芋凝胶品质及扩大魔芋凝胶在素食行业中的快速应用,该研究以魔芋粉、绿豆淀粉为研究对象,以硬度和持水力为评价指标,通过单因素和正交试验得到制备绿豆淀粉魔芋凝胶基体的最优工艺。同时利用差式扫描量热仪（Differential scanning calorimeter,DSC）、傅立叶红外光谱（Fourier-transform infrared spectroscopy,FT-IR）、扫描电镜（Scanning electron microscope,SEM）和X-射线衍射（X-ray diffraction,XRD）等手段对添加绿豆淀粉前后的魔芋凝胶性能进行对比分析。结果表明,制备绿豆淀粉魔芋凝胶基体最优工艺参数为淀粉量3.00 g、碱含量7.00%、冷冻时间1.50 h、溶胀时间1.50 h、柠檬酸浓度0.50% m/V。此条件下制备的绿豆淀粉魔芋凝胶基体硬度为1782.61 g,持水力为92.63%,较纯魔芋凝胶相比分别提高了54.30%、2.41%,具有更好的凝胶状态和持水效果。性能表征分析进一步证明了绿豆淀粉与魔芋粉具有相容性,绿豆淀粉魔芋混合体系相互作用加强,形成了网络状的空间结构,具有更好的质构特性。     

冻融处理对大豆分离蛋白及其糖基化产物凝胶理化性质的影响

为探究大豆分离蛋白(SPI)及其糖基化产物凝胶在不同温度冻融过程中的变化情况,采用SPI和SPI-葡聚糖(分子质量分别为10、40、70 kDa)轭合物制备凝胶,对其进行-18、-80℃冻融处理,测定冻融处理前后凝胶的表面疏水性、总游离巯基含量、凝胶网络结构、凝胶强度和持水力,研究冻融条件对SPI及其糖基化轭合物凝胶理化性质的影响。结果表明：与冻融前比较,-18、-80℃冻融处理后SPI凝胶表面疏水性显著增加,总游离巯基含量降低,凝胶网络结构被破坏,凝胶强度总体降低,持水力升高。与冻融前比较,SPI-葡聚糖轭合物凝胶在-18℃冻融处理后表面疏水性显著增加,最高增加了23.29%(SPI-40 kDa葡聚糖轭合物),而-80℃冻融处理后无显著变化;-18℃冻融处理后总游离巯基含量下降,-80℃冻融处理后总游离巯基含量升高;冻融处理后凝胶结构未发生明显变化,而凝胶强度均降低;持水力在-18℃冻融处理后总体变化不大,-80℃冻融处理后升高。综上,-18℃冻融处理对SPI凝胶及SPI-葡聚糖轭合物凝胶的总游离巯基含量、凝胶强度的影响总体小于-80℃冻融处理,且3种分子质量的葡聚糖改性的SPI-...     

基于碱性电解水形成的魔芋热不可逆凝胶性质研究

首次采用碱性电解水(alkaline electrolyzed water, AEW)代替传统凝固剂制作魔芋热不可逆凝胶(魔芋凝胶),探究AEW对魔芋凝胶性能的影响,为AEW应用于魔芋凝胶食品的开发利用提供理论依据和技术参考。该文以魔芋精粉为原料,探索了AEW为凝固剂制作魔芋凝胶的方法,基于色度、持水性、凝胶强度、冻融稳定性、质构、流变学、表观结构等指标研究该凝胶的性能,并以传统凝固剂氢氧化钙、碳酸钠制作的魔芋凝胶为对照,进行分析比较。结果表明,AEW可作为凝固剂制作魔芋热不可逆凝胶,且该凝胶在色度、持水性、凝胶强度等方面优于工业生产常用的以氢氧化钙凝固剂制作的凝胶。     

冷冻魔芋复合凝胶保水性和质构特性的调控

本研究将瓜尔豆胶、大豆油、乳化剂依次加入到魔芋凝胶中,以探究其对冷冻魔芋凝胶保水性和质构特性的影响。首先添加瓜尔豆胶到魔芋凝胶中,相比于控制组(纯魔芋凝胶),冷冻后的魔芋/瓜尔豆胶复合凝胶的保水性能提升,其冷冻析水率最多减小了3.63%,持水率最大升高了4.68%,硬度最多增大了930.74 g。为了进一步提高冷冻复合凝胶的保水性,将大豆油和乳化剂添加入魔芋/瓜尔豆胶复合凝胶中。添加大豆油可以增大魔芋/瓜尔豆胶凝胶的保水性,但复合凝胶硬度有所降低。在魔芋/瓜尔豆胶/大豆油复合凝胶中添加5种不同的乳化剂进行对比,发现单甘油脂肪酸酯对提高冷冻凝胶的保水性的效果最好。当瓜尔豆胶、大豆油和单甘油脂肪酸酯在复合凝胶中的比例分别为0.10%、5%和0.10%时,对比控制组,冷冻复合凝胶的析水率由25.37%降低到10.19%,持水率由62.55%升高至82.83%,但凝胶硬度降低。瓜尔豆胶、大豆油和单甘油脂肪酸酯的复合添加可以有效改善魔芋凝胶在冷冻后的保水能力,并改变了凝胶的质构特性。本研究为调控冷冻魔芋复合凝胶的性能提供了数据支撑,也为冷冻魔芋复合凝胶产品的生产提供了理论参考。     

魔芋葡甘聚糖的酯化及其产物特性

为提高魔芋葡甘聚糖性能,扩大其应用范围,用六偏磷酸钠与魔芋葡甘聚糖进行酯化反应. 采用红外光谱测得其产物的结构表征,并研究了其性能.结果表明:酯化改性的最佳条件为:m(六偏磷酸钠)∶m(葡甘聚糖)=1∶8,温度 55 ℃,pH值 2,时间 1.5 h.在此条件下,产物的粘度、溶胶稳定性、冻融稳定性、透明度均有改善,产物适用于冷冻食品等行业.     

冻融处理不同来源淀粉魔芋复合凝胶特性及其影响

为探究冻融处理不同来源淀粉对魔芋凝胶的影响,以6 种不同的市售淀粉,按不同淀粉与魔芋粉的质量比来制备冷冻复合凝胶。基于各种不同来源淀粉理化性质,综合分析复合凝胶的质构特性和持水性差异,通过相关性分析探究不同来源淀粉对魔芋凝胶的影响。结果表明,不同来源淀粉间直链淀粉含量、糊化特性以及淀粉凝胶的流变特性存在差异,添加不同来源淀粉均可以改善冷冻复合凝胶的凝胶品质,降低凝胶硬度的同时提高弹性,淀粉与魔芋质量比（2∶8）可提高复合凝胶的持水性。而不同来源淀粉的添加对凝胶品质影响存在差异性,其中小麦淀粉魔芋复合凝胶综合品质最优,与纯魔芋凝胶相比具有较好的弹性及内聚性。小麦淀粉与魔芋粉质量比为1∶9 时改善冷冻复合凝胶特性效果最佳。     

冷榨豆粉凝胶特性及其在千页豆腐制作中的应用

目的 研究不同加热温度(90、95、100℃)、不同加热时间(20、30、40、50、60 min)对冷榨豆粉凝胶特性的影响及其在千页豆腐中的应用。方法 以凝胶强度和持水性为指标探究冷榨豆粉凝胶特性; 以黏度、储能模量和损耗模量为指标探究冷榨豆粉凝胶在热处理过程中流变学特性变化。采用单因素实验和响应面优化实验对冷榨豆粉基千页豆腐加工工艺进行优化, 探讨不同冷冻条件对其品质影响。结果 热处理使冷榨豆粉分散液形成弹性凝胶(储能模量大于损耗模量)。冷榨豆粉凝胶黏性、储能模量、损耗模量、随着加热温度的升高及加热时间的延长而增加, 凝胶强度和持水性同样随之增加, 且分别在100℃加热90 min处达到最大[(130.57±0.02) g, 0.99 g/g]。经优化得出冷榨豆粉基千页豆腐最佳工艺条件为: 冷榨豆粉添加量100.00 g、冰水添加量575.00%、谷氨酰胺转氨酶(transglutamianse, TG)添加量1.64%、大豆分离蛋白(soy protein isolate, SPI)添加量46.00%。优化后的冷榨豆粉基千页豆腐的硬度为2271.24 g, 弹性为0.95。在-18和-45℃两种冷冻温度下, 千页豆腐中结合水(T2b)含量随着冷冻时间的延长而减小, 弛豫时间缩短, 凝胶网络中的水受到限制。降低冷冻温度可缩短水受到限制的时间, 导致水的流动性降低。不易流动水(T21)含量随着冷冻时间的增加先增加后减小, 且分别在冷冻7和3 d处达到最大。结论 热处理会对冷榨豆粉凝胶特性产生积极的影响。冷冻会使冷榨豆粉基千页豆腐内部结构中的更多结合水向自由水转移, 使冷榨豆粉基千页豆腐结构疏松, 孔径变大。     

冻融处理对胡萝卜膨化效果的影响研究

以胡萝卜为原料,结合压差膨化技术,研究冻融前处理对胡萝卜膨化效果的影响。以膨化后产品的脆度和色泽为指标,通过对冷冻温度、冷冻时间、融冻温度、冻融次数及其协同作用影响因素的实验分析,来探究冻融处理对胡萝卜膨化效果的影响,确定胡萝卜压差膨化冻融前处理工艺参数。结果表明:冷冻温度和冷冻时间对脆度均具有显著影响(p0.05);冻融次数对脆度的影响较为显著。优选胡萝卜冻融处理参数为:冷冻温度-18℃,时间120min,融冻温度(80±2)℃时融冻一次,膨化后产品的脆度均值达到211.1N/s,明亮度L*值为46.99,产品品质较好。     

超声波-热水浴溶胀对魔芋复合粉丝品质的影响

研究以魔芋精粉和大豆分离蛋白为原料,采用超声波-热水浴溶胀工艺制备魔芋复合粉丝,通过与常温溶胀、热水浴溶胀和超声波溶胀制备的魔芋复合粉丝的质构特性和粉丝的基本品质特性进行比较,结论如下:当超声波功率70W、超声处理时间4min、超声波温度50℃和热水浴温度45℃时,魔芋复合粉丝能获得最佳的凝胶强度;通过多重比较分析可得,超声波-热水浴溶胀制备的魔芋复合粉丝硬度、黏性、咀嚼性、断条率、白度和感官特性显著改善,弹性、凝聚性和烹煮损失率与其他3种溶胀方法制备的魔芋复合粉丝不存在显著差异,析水率显著提高。     

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