光照和温度对草鱼和三文鱼鱼肉贮藏品质的影响

采用4、10(无光照)、10(5 000 lx)、25℃条件,同时贮藏草鱼鱼片(除去红肉)和三文鱼鱼片,研究光照和温度对草鱼和三文鱼贮藏品质的影响。结果表明,草鱼和三文鱼贮藏过程中pH值、挥发性盐基氮(total volatile basic nitrogen,TVB-N)值、硫代巴比妥酸(thiobarbituric acid,TBA)值和色差变化差异显著(P0.05),且菌落总数(total viable count,TVC)、pH值、TVB-N值、TBA值、色差、ATP分解产物(adenosine triphosphate-related decomposition products)K值均随着贮藏时间的延长而增加。光照(5 000 lx)对于草鱼、三文鱼贮藏过程中的pH值变化、TBA值变化影响显著(P0.05),能使鱼肉中pH值增加量高于避光保存,促进光氧化,提高TBA值增加速率,而对于TVC、TVB-N值、K值、色差变化影响不显著(P0.05)。贮藏温度的差异(4、10℃)对两种鱼肉品质变化都有显著影响(P0.05)。     

冰温保鲜和冷藏保鲜对生食大西洋鲑品质影响的比较研究

目的探讨冰温保鲜和冷藏保鲜对生食大西洋鲑品质变化的影响。方法将大西洋鲑分别置于-1.8℃冰温条件和4.0℃冷藏条件下贮藏,测定菌落总数、pH值、挥发性盐基氮(total volatile basic nitrogen,TVB-N)值、色差值、K值和感官评分,通过这一系列评价指标,综合分析大西洋鲑在冰温保鲜条件和冷藏保鲜条件下品质变化的不同。结果随着贮藏时间的延长, 2组的菌落总数值、TVB-N值、K值均呈上升趋势, pH值在冰温保鲜条件和冷藏保鲜条件下变化趋势相近,色差值在2个保鲜条件下波动变化没有明显差异,感官评分在2个不同温度条件下总体均呈现下降趋势。在冷藏保鲜条件下,生食大西洋鲑的货架期为2 d;在冰温保鲜条件下,生食大西洋鲑的货架期为5d。结论冰温保鲜方式可将生食大西洋鲑的货架期延长3d,与冷藏保鲜方式相比,冰温保鲜方式在大西洋鲑的贮藏过程中体现了良好的保鲜效果。     

4℃、20℃贮藏下鲍鱼品质变化

以新鲜鲍鱼为原料,应用选择培养基、高效液相色谱技术等对贮藏期间的微生物、生物胺及相关理化指标(感官评价、挥发性盐基氮(Total volatile basic nitrogen,TVB-N)、pH值)进行测定,研究4℃、20℃贮藏下鲍鱼品质劣变的优势菌以及危害因子生物胺的产生情况。2种贮藏温度下,假单胞菌和腐败希瓦氏菌均为优势腐败菌,腐胺、尸胺含量和TVB-N值、总菌落数、假单胞菌、腐败希瓦氏菌数量有良好的相关性(R2=0.983~0.914),尸胺、腐胺可以作为鲍鱼品质评价的参考指标,4℃可以有效抑制鲍鱼的腐败进程,延长鲍鱼保质期。     

大西洋鲑贮藏过程中微生物生长预测系统的构建

菌落总数、假单胞菌数量和希瓦氏菌数量是影响大西洋鲑新鲜度的重要指标,因此,探明上述微生物的变化情况将有利于监测和预判贮运过程中大西洋鲑的品质。本研究通过修正的Gompertz模型、Baranyi and Roberts模型以及Belehradek方程拟合大西洋鲑在不同贮藏温度下的菌落总数、假单胞菌数量和希瓦氏菌数量的变化情况,得到大西洋鲑贮藏过程中微生物数量的变化规律,并运用Visual Basic语言编写生成微生物生长预测系统。结果表明:通过比较修正的Gompertz模型和Baranyi and Roberts模型拟合所得的4、10、25℃贮藏温度下微生物生长参数发现,Baranyi and Roberts模型更适宜作为一级模型反映大西洋鲑贮藏过程中微生物数量随时间的变化情况;运用该模型拟合大西洋鲑在不同贮藏温度下菌落总数、假单胞菌数量和希瓦氏菌数量所得的决定系数(R~2)均大于0.9,其中25℃下分别为0.995、0.994、0.952,10℃下分别为0.993、0.996、0.997,4℃下分别为0.981、0.995、0.914。根据Baranyi and Roberts模型拟合所得参数利用Belehradek方程拟合微生物生长延滞时间、最大比生长速率与贮藏温度的关系,并在此基础上通过Visual Basic语言编写生成微生物生长预测软件,快速获得了不同贮藏温度下微生物的数量及生长曲线,为预测和监控大西洋鲑中微生物生长提供一种高效、便捷的工具。     

0℃贮藏卵形鲳鲹货架期的研究及特定腐败菌的分离与鉴定

为研究0℃贮藏卵形鲳鲹的货架期,并分离鉴定其特定腐败菌,以0℃贮藏卵形鲳鲹为研究对象,监测其感官品质、菌落总数、TVB-N值的变化以确定其保质期,采用传统选择性培养基法结合16S r DNA技术,研究了卵形鲳鲹的菌落特征、分离与鉴定腐败菌,并以腐败物质的产量因子(Y_(TVB-N/cfu))为评价标准,定量测定了贮藏末期优势菌的致腐能力。结果表明:0℃贮藏下9 d后卵形鲳鲹的感官品质、货架期达到终点;贮藏末期(9 d)荧光假单胞菌(Pseudomonas fluorescens23.61%)、蜡样芽孢杆菌(Bacillus cereus 20.06%)、草莓假单胞菌(Pseudomonas fragi 17.03%)、沙门氏菌(Salmonella enteric 11.62%)和大肠杆菌(Escherichia coli 10.53%)数量占绝对优势,通过对贮藏末期5株数量优势菌的致腐能力测定发现,荧光假单胞菌致腐能力最强(产量因子:4.66×10~(-8)mg TVB-N/cfu),蜡样芽孢杆菌(3.73×10~(-8) mgTVB-N/cfu)和草莓假单胞菌(3.53×10~(-8) mgTVB-N/cfu)次之,大肠杆菌(2.61×10~(-8) mgTVB-N/cfu)和沙门氏菌(2.46×10~(-8) mgTVB-N/cfu)最弱,综合比较,最终确定荧光假单胞菌、蜡样芽孢杆菌以及草莓假单胞菌为0℃贮藏下卵形鲳鲹的特定腐败菌。     

低压静电场处理对竹节虾(Penaeus japonicus)微冻贮藏过程中品质的影响

为探明低压静电场对舟山竹节虾保鲜过程中品质的影响,以舟山竹节虾为研究对象,以-4℃微冻贮藏的竹节虾为对照组,以静电场(3000 V、50 Hz)-4℃微冻贮藏的竹节虾为实验组,进行对照试验。通过对0~28 d内竹节虾冰点、pH、汁液流失率、挥发性盐基总氮(TVB-N)、菌落总数(TVC)、硫代巴比妥酸值(TBA)、质构分析(TPA)等理化指标的测定与组织微观结构分析,探明低压静电场对舟山竹节虾贮藏保鲜过程中品质的影响。研究结果表明,未经电场处理的对照组竹节虾贮藏至28 d时,pH波动明显,汁液损失严重,TVB-N值达到30.42 mg/100 g,TVC值增长到了7.06 lg(CFU/g),TBA值高达0.82 mg/kg,肌肉纤维之间产生了明显断裂和无规律扩散,此时竹节虾处于不可食用状态;而经过电场处理的实验组竹节虾品质较好,pH波动范围≤ 0.04,竹节虾汁液流失率仅为5.01%,TVB-N、TVC值远低于对照组,脂肪氧化程度显著低于对照组(P<0.05),硬度和弹性下降缓慢,经H&E染色亦发现微观肌间结构完整,缝隙数量很少,无明显冰晶,竹节虾处于可食状态。实验结果表明低压静电场的添加可以有效延缓竹节虾贮藏过程中的品质变化,该项技术成果对改变传统水产品的保鲜方式具有重要的指导意义。     

非真空包装烧鸡贮藏中品质变化和腐败菌分析

对非真空包装烧鸡在低温(0~4℃)贮藏过程中品质和腐败菌种群变化进行研究,通过分析贮藏期间微生物生长情况及pH值、TVB-N值、TBARS值变化,结合感官质量变化,确定低温条件下贮藏产品的货架期和腐败菌群。结果表明:低温贮藏条件下,初始菌数为4.95×103 cfu/g时,产品的货架期约为3 d;酵母菌、假单胞菌属、乳酸菌和葡萄球菌属是产品腐败时的主要微生物;酵母菌、假单胞菌属是优势腐败菌。     

北太平洋鱿鱼低温贮藏中的品质变化与货架期

以感官、色差、质构、总挥发性盐基氮(TVB-N)和微生物为指标,研究了北太平洋鱿鱼在0(冰藏)、5、10、15℃贮藏过程中的品质变化和货架期,并探讨了各指标的一致性程度。结果表明,在0、5、10、15℃贮藏过程中,北太平洋鱿鱼的高品质期终点分别为360、239、96、47 h,货架期终点分别为525、286、147、86 h;不同温度贮藏过程中,a*值无显著差异(p0.05),L*值、b*值均呈现上升趋势,剪切力与咀嚼性均先增加后降低。各温度高品质期终点和货架期终点时TVB-N均值分别为(17.15±0.31)、(30.06±0.92)mg/100g,菌落总数(TVC)分别为(5.89±0.40)、(8.33±0.30)lg(CFU/g),嗜冷菌数分别为(5.61±0.5)、(8.36±0.23)lg(CFU/g),假单胞菌数分别为(5.23±1)、(7.58±0.57)lg(CFU/g);相关性分析表明,TVB-N、TVC、嗜冷菌数和假单胞菌数作为北太平洋鱿鱼低温贮藏中的品质变化指标与感官评分有较好的一致性(r0.9)。     

低压静电场处理对带鱼微冻贮藏期间品质变化影响

为研究低压静电场技术(Low voltage electrostatic field,LVEF)对带鱼微冻贮藏保鲜过程中品质变化影响,本文以新鲜舟山带鱼为实验原料,由冷冻曲线法得其冰点后予以分组。其中,实验组在-4 ℃条件下进行低压静电场(3000 V、50 Hz)处理,以未做电场处理样品为对照组。期间,分别进行两组样品的pH、总挥发性盐基氮(TVB-N)、硫代巴比妥酸值(TBA)、菌落总数(TVC)与K值测定,结合苏木精-伊红(Hematoxylin＆Eosin,H＆E)染色与扫描电镜(SEM)分析,综合评价LVEF协同微冻对带鱼贮藏期间品质变化的影响。结果表明:对照组样品在第21 d时的TVB-N值为29.81 mg/100 g,接近不可食状态;第28 d时的TBA值为1.78 mg MDA/100 g,TVC值超过腐败限值,K值增至88.71%,背肌肌肉纤维变形收缩,产生严重扭曲折叠,鱼体腐败严重;而处理组样品在第28 d时的TVB-N、TBA与TVC值均低于对照组,pH变化幅度不明显,K值为63.17%,细胞间结构完整大小均匀,仅有轻微组织损伤,保鲜效果好。因此,LVEF技术能有效缓解带鱼微冻贮藏过程中的品质劣变,与对照组相比,其可延长微冻带鱼货架期7 d。     

保鲜盒包装冷鲜牛肉贮藏期间品质及菌相变化

为研究保鲜盒包装冷鲜牛肉贮藏期间的感官品质、新鲜度变化,并初步分析其优势菌相,测定0℃~4℃下贮藏第0、1、3、5、7天时肉样的感官指标、挥发性盐基氮值(total volatile basic nitrogen,TVB-N)、pH值、硫代巴比妥酸反应物值(thiobarbituric acid reactive substances,TBARS)、菌落总数、大肠菌群的变化,以及乳酸菌、假单胞菌、肠杆菌以及热死环丝菌的生长情况。结果表明:保鲜盒包装冷鲜牛肉在0℃~4℃条件下最佳冷藏期为3d,贮藏第5天时为次鲜肉,第7天时已腐败;假单胞菌、乳酸菌、热死环丝菌为其优势腐败菌。     

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