热处理联合不同包装对鲜切马铃薯贮藏品质的影响

为解决鲜切马铃薯贮藏品质劣变快、货架期短的问题,本研究探讨45℃热处理3 min联合真空包装和30%CO2+70%N2气调包装对鲜切马铃薯贮藏品质的影响。结果表明：热处理联合气调包装可延缓鲜切马铃薯呼吸速率的上升,显著抑制丙二醛（malondialdehyde,MDA）含量上升及苯丙氨酸解氨酶（phenylalanine ammonia-lyase,PAL）、过氧化物酶（peroxidase,POD）、多酚氧化酶（polyphenol oxidase,PPO）活力（P<0.05）,有效维持总酚、抗坏血酸（ascorbic acid,AsA）、可溶性固形物含量（soluble solids content,SSC）和淀粉含量,抑制细菌菌落总数的增长,保持马铃薯原有挥发性风味和感官品质。综上,热处理联合气调包装可以使鲜切马铃薯保持较好的感官和营养品质,抑制微生物生长以及褐变酶活性,从而延长鲜切马铃薯货架期。     

不同抗褐变剂处理对鲜切慈姑褐变的影响

以慈姑为研究材料,研究1%抗坏血酸和0.2 g/L阿魏酸2个抗褐变剂处理对鲜切慈姑冷藏(4±1℃)过程中褐变的影响。通过测定贮藏过程中鲜切慈姑褐变度、可溶性固形物含量(TSS)、总酚、类黄酮含量、多酚氧化酶(PPO)、过氧化物酶(POD)和苯丙氨酸解氨酶(PAL)活性等各项指标的变化,确定抗褐变剂对鲜切慈姑褐变的影响。结果发现, 2种抗褐变剂均能有效抑制鲜切慈姑的褐变,较好维持鲜切慈姑TSS含量,降低鲜切慈姑贮藏过程中总酚、类黄酮含量的上升,有效抑制褐变关键酶PPO、POD和PAL活性,不同抗褐变剂抑制效果不同,但是从褐变度和营养品质上看0.2 g/L阿魏酸处理效果较好。     

高浓度二氧化碳气调包装通过调节酚代谢抑制鲜切莲藕的酶促褐变

鲜切莲藕褐变的主要原因是酶促褐变,高浓度CO_2气调包装(Modified-atmosphere packaging,MAP)可以有效延缓鲜切果蔬褐变,而苯丙氨酸解氨酶(L-phenylalanine ammonia-lyase,PAL)、多酚氧化酶(Polyphenol oxidase,PPO)和过氧化物酶(Peroxidase,POD)的编码基因是引起果蔬褐变的主要基因。然而,高浓度CO_2 MAP对鲜切莲藕片PAL、PPO、POD酶及其编码基因表达的影响却鲜有报道。本文分析了100%CO_2MAP对鲜切莲藕贮藏过程中褐变度、总酚含量、PAL、PPO和POD酶活性及其编码基因表达的影响。结果表明:100%CO_2 MAP对延缓鲜切莲藕褐变有较好效果,且100%CO_2 MAP贮藏期间鲜切莲藕PAL、PPO和POD酶活性随褐变程度的增加而同步变化。此外,Nn PAL1,Nn PPOA和Nn POD2/3的表达变化与PAL,PPO和POD酶活性的变化及褐变相一致,说明高浓度CO_2 MAP可能通过下调Nn PAL1,Nn PPOA和Nn POD2/3的表达来延缓鲜切莲藕褐变。     

抗坏血酸钙和ε-聚赖氨酸对鲜切甘薯保鲜护色效果的影响

以二郎苕甘薯为试验材料,研究在4℃贮藏条件下,抗坏血酸钙和ε-聚赖氨酸2种绿色保鲜剂及其复合处理对鲜切甘薯褐变度、菌落总数、总酚含量、苯丙氨酸解氨酶(Lphenylalanin ammonia-lyase,PAL)、多酚氧化酶(polyphenol oxidase,PPO)和过氧化物酶(Peroxidase,POD)活性等的影响。研究结果表明,与对照相比,5%抗坏血酸钙+0.03%ε-聚赖氨酸浸泡10min能够有效降低鲜切甘薯贮藏期间的褐变度和菌落总数,保持鲜切薯块较高的总酚含量,抑制鲜切薯块PAL、PPO、POD活性的升高,对提高鲜切甘薯贮藏品质和延长贮藏周期具有一定效果。     

OPP/CPP膜中不同气体比例对鲜切马铃薯片保鲜的影响

为研究鲜切马铃薯片在不同气体比例下的品质变化,以品质优良的马铃薯为试材,采用OPP/CPP膜进行气调包装,以空气包装组为对照,分析不同气体比例下的鲜切马铃薯片在贮藏期间的感官品质变化,并对其褐变度、多酚氧化酶(PPO)活性、过氧化物酶(POD)活性、丙二醛(MDA)含量、V_C含量及菌落总数进行测定。结果表明:在4℃条件下,采用40%CO_2+50%O_2+10%_N2的混合气对鲜切马铃薯片进行气调包装,与其他组相比,可以维持较高的感官品质,显著(p0.05)抑制酶促褐变反应、PPO活性和POD活性,显著(p0.05)影响微生物的增殖与MDA的积累,V_C损失显著减少,感官评价较高,保鲜效果最好。     

复合保鲜剂结合MAP对鲜切茄子贮藏品质的影响

为延长鲜切茄子的保鲜时间,研究单一气调包装(2%CO2+5%O2+93%N2)和保鲜液(1.5%壳聚糖+1%抗坏血酸+1%氯化钙+2%柠檬酸)结合气调包装对鲜切茄子品质的影响。以感官评分、褐变度、硬度、多酚氧化酶(PPO)活性和细菌总数为指标,分析鲜切茄子于(10±1)℃下贮藏8d内的品质变化。结果表明:贮藏8d后,对照组样品的L*值、硬度、PPO酶活性和细菌总数分别为75.66、7.41kg/cm2、68.77U/(min·g)和5.52lg CFU/g,而经保鲜液结合气调包装的鲜切茄子各指标分别为82.51、10.05kg/cm2、23.70U/(min·g)和2.87lg CFU/g。气调包装能够抑制鲜切茄子的褐变、萎蔫等感官品质的下降,并抑制PPO活性的增加和细菌的生长繁殖,尤其在结合保鲜液处理后效果更加明显,贮藏8d仍保持较好的品质。     

热处理对鲜切马铃薯褐变及挥发性物质的影响

褐变是影响鲜切马铃薯贮藏品质的重要因素之一。该研究探讨45、50℃热处理1～4 min对鲜切马铃薯褐变和挥发性风味物质的影响,以期为鲜切马铃薯品质保持提供调控技术和理论依据。45、50℃热处理4 min鲜切马铃薯在室温下2 h就观察到轻微的褐变,L*值下降10.51%、14.96%;a*值上升2.74、3.84,而45、50℃热处理1～3 min组鲜切马铃薯6 h内均未观察到褐变现象。与对照组相比,45℃热处理1～3 min组鲜切马铃薯硬度无显著变化,而其余热处理组硬度显著降低;两种温度1～3 min热处理组鲜切马铃薯苯丙氨酸解氨酶（PAL）、过氧化物酶（POD）酶活性和总酚含量分别降低了27.81%～33.68%、18.33%～50.37%、6.22%～28.92%。45℃热处理1～3min和50℃热处理1～2min热处理组较好的维持鲜切马铃薯原有的挥发性风味物质。总的来说,45、50℃热处理1～3 min可有效的抑制鲜切马铃薯褐变;其中,45℃热处理3 min抑制马铃薯褐变的同时较好维持了硬度、色泽、抗坏血酸含量和挥发性风味物质。     

马齿苋提取物对鲜切苹果褐变的影响

酶促褐变是影响鲜切果蔬品质及商业价值的关键问题之一。为探究马齿苋提取物在果蔬保鲜方面的应用价值,以鲜切苹果为研究材料,采用质量分数0.05%马齿苋提取物溶液浸泡鲜切苹果5min,在(4±1)℃存放8d。以鲜切苹果的褐变指数、多酚氧化酶(polyphenol oxidase,PPO)活力、苯丙氨酸解氨酶(phenylalanine ammonia-lyase,PAL)活力、过氧化氢酶(catalase,CAT)活力、过氧化物酶(peroxidase,POD)活力、丙二醛(malondiadehyde,MDA)含量、抗坏血酸含量以及DPPH自由基清除能力为评价指标,分析马齿苋提取物对鲜切苹果褐变及贮藏品质的影响。结果表明:与蒸馏水对照组相比,马齿苋提取物溶液处理能有效抑制鲜切苹果的褐变程度,在降低POD、PPO和PAL活力方面也有明显效果,能够在保证膜完整性的基础上减少细胞膜出现的损伤。相关性分析表明:鲜切苹果的褐变指数与CAT活力、抗坏血酸含量、DPPH自由基清除能力呈现极显著负相关(P<0.01),与MDA含量、PPO活力、POD活力、总酚含量呈极显著正相关(P<0.01)。马齿苋提取物溶液处理的鲜切苹果抗褐变效果较好,同时贮藏后鲜切苹果的抗氧化能力也有一定提高。     

复合保鲜剂对鲜切苹果贮藏品质的影响

以鲜切苹果为试材,研究不同浓度柠檬酸、壳聚糖及D-异抗坏血酸钠(D-sodium erythorbate,D-SE)复合保鲜剂处理5 min,4℃贮藏期间鲜切苹果贮藏品质特性的变化规律。结果表明:复合保鲜剂处理组可保持鲜切苹果感官品质、抑制鲜切苹果多酚氧化酶(PPO)及过氧化物酶(POD)活性,对鲜切苹果有较好的保鲜效果;1.0%柠檬酸+0.5%壳聚糖+1.0%D-异抗坏血酸钠溶液处理组优于其他处理组,能在4℃贮藏12 d内保持鲜切苹果外观品质与食用品质品质,有效抑制鲜切苹果果肉褐变,延缓硬度和TSS含量降低速率,降低与褐变有关的多酚氧化酶(PPO)及过氧化物酶(POD)活性。     

高氧气调包装对鲜切胡萝卜的保鲜效果

研究了不同氧分压条件对鲜切胡萝卜保鲜效果的影响,评定其在贮藏过程中感官品质、呼吸强度、PPO、POD、PAL活性的变化。结果表明,40%氧气包装不适合鲜切胡萝卜贮藏保鲜。100%氧气包装的保鲜效果最好,可有效抑制鲜切胡萝卜呼吸强度以及PPO、POD、PAL的活性。60%、80%氧气包装的保鲜效果次之,但均可起到保鲜的作用。     

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