内源化学反应及细菌活动对冰温贮藏罗非鱼片腐败变质的贡献研究

目的 评估内源化学反应及细菌活动对冰温贮藏罗非鱼片腐败变质的贡献。方法 研究经抑菌处理及未经抑菌处理的罗非鱼片在冰温贮藏期间的菌落总数、挥发性盐基氮(totalvolatilebasicnitrogen,TVB-N)值、pH、硫代巴比妥酸(thiobarbituric acid, TBA)值及感官鲜度的变化,采用电子鼻监测挥发性成分的变化,并对未经抑菌处理罗非鱼片各指标与菌落总数间进行皮尔逊相关性分析。结果 贮藏期间经抑菌处理的样品的菌落总数始终小于5.05 log CFU/g, TVB-N值小于3.00 mg/100 g, pH及电子鼻测定的各种挥发性成分基本未变,未发生感官腐败,虽然TBA值有所增加(P<0.05),但始终低于0.05 mg MDA/100 g。而未经抑菌处理的罗非鱼片,菌落总数在21 d时达到9.19 log CFU/g, TVB-N值增至40.69 mg/100 g, pH由6.65增至7.63,电子鼻测定的氮氧化合物、硫化物及有机硫化物骤增, TBA值增至0.072 mg MDA/100 g,显著高于抑菌处理的样品,感官腐败明显。结论 冰温贮藏条件下内源...     

大菱鲆微冻贮藏过程中的品质变化规律

以微生物、理化和感官为指标,对大菱鲆在-2℃微冻贮藏过程中的品质变化进行了研究。试验结果表明,大菱鲆在-2℃贮藏时其货架期可达到20 d。货架期终点时菌落总数为5.99 ln(CFU/g),pH值为6.88,TVB-N值为37.08 mg N/100 g,TBA值为1.81 mg MDA/kg。硬度、弹性和色差b*值与贮藏时间呈显著负相关。电子鼻LA分析结果与贮藏期鱼肉品质变化相吻合。     

高压静电场解冻对冻罗非鱼片品质的影响

本文以冻罗非鱼片为研究对象,分析了不同高压静电场(0、1.8、3.8 k V)、不同解冻温度(25、15、5℃)条件下解冻,其解冻曲线、解冻时间和解冻速率的变化情况;并以解冻损失率、菌落总数、感官品质、色差值、总挥发性盐基氮(TVB-N)、脂质氧化(TBA)等为衡量指标,研究了高压静电场解冻对罗非鱼片品质指标变化影响。结果显示,对各解冻温度组,3.8 k V高压静电场解冻速率更快,解冻时间更短,在5℃时,3.8 k V高压静电场解冻速率是对照组速率的1.59倍;高压静电场解冻后鱼片TVB-N值和菌落总数都显著低于对照组,15℃时,3.8 k V高压静电场解冻候的菌落总数为4.29 log CFU/g显著低于对照组的4.67 log CFU/g(p0.05);总体上高压静电场解冻不仅可以加速冻罗非鱼片的解冻,而且能更好地保持鱼肉的品质,从解冻速率和品质指标综合考虑,15℃、3.8 k V高压静电场解冻是最佳的选择。     

养殖尼罗罗非鱼鲜度特征及动力学模型构建

通过感官、化学、微生物学方法对低温(0～10℃)和室温(25℃)贮藏尼罗罗非鱼鲜度特征进行评价,确定产品货架期及货架期终点细菌种群,运用平方根相对腐败速率方程构建货架期预测模型。结果表明:鲜鱼感官品质良好,菌落总数、假单胞菌数、产H2S细菌数和挥发性盐基氮(TVBN)分别为(4.41±1.13)、(3.39±1.09)、(2.01±0.88)(lg(CFU/g))和(8.53±0.73)mg/100g。低温贮藏罗非鱼货架期终点时,菌落总数、假单胞菌、产H2S细菌数和TVBN分别为(7.79±0.35)、(7.24±0.45)、(6.35±0.23)(lg(CFU/g))和(19.90±2.10)mg/100g,确定货架期为5.5～20.1d,优势菌是假单胞菌属,而室温贮藏的罗非鱼货架期为1.3d,优势菌为气单胞菌。0～25℃范围贮藏的罗非鱼品质动力学模型参数Tmin为-8.9℃,并用3、8℃恒温和变温等实际流通条件对货架期预测模型进行了验证,显示货架期预测模型能有效评价0～25℃范围内的罗非鱼品质。     

不同温度贮藏对黄鳍鲷鱼肉鲜度与品质的影响

以黄鳍鲷（Acanthopagrus latus）为研究材料,通过测定鱼肉菌落总数、pH值、挥发性盐基氮（total volatile basic nitrogen,TVB-N）值、硫代巴比妥酸（2-thiobarbituric acid,TBA）值和剪切力等指标,结合感官评定,设立4℃冷藏为对照组,研究0℃和微冻（-4℃）贮藏对黄鳍鲷鱼肉鲜度和品质的影响。结果表明：在贮藏期间,各贮藏组黄鳍鲷鱼肉的菌落总数、TVB-N和TBA值均呈现上升趋势,鱼肉pH值呈先稍下降后再上升的趋势,而鱼肉剪切力和感官评分均呈逐渐下降趋势。0℃和微冻两贮藏组黄鳍鲷鱼肉各项指标的变化速率均小于4℃冷藏对照组,0℃和微冻保鲜效果明显优于4℃冷藏保鲜;0℃和微冻贮藏组,黄鳍鲷贮藏7 d后鱼肉菌落总数分别为6.88 lg（CFU/g）和5.72 lg（CFU/g）,TVB-N值分别为20.54 mg/100 g和11.40 mg/100 g,TBA值分别为0.88 mg/100 g和0.38 mg/100 g,剪切力分别为4.96 N和5.51 N,说明微冻贮藏能更好地抑制鱼肉微生物繁殖,有效地减缓鱼肉蛋白质分解和脂肪氧化,较好地保持鱼肉嫩度和品质;相比于4℃冷藏,0℃和微冻下贮藏的黄鳍鲷鱼肉货架期至少可延长2 d和8 d。     

茶多酚对罗非鱼微冻保鲜的影响

以罗非鱼为实验对象,研究茶多酚对罗非鱼片在微冻保鲜过程中品质变化的影响。通过罗非鱼片冻结曲线的绘制,确定其冻结点。同时,结合感官评定、菌落总数、硫代巴比妥酸值(TBA值)、挥发性盐基氮(TVB-N值)等指标测定,综合评价茶多酚结合微冻处理对罗非鱼片品质的影响。结果表明:罗非鱼的冻结点为-2.5℃左右。经0.1%茶多酚处理后的罗非鱼片的菌落总数、p H、TBA值、TVB-N值与对照组相比降低显著(p0.05),其感官评分值显著提高(p0.05),且使其货架期由19d延长至28d。     

低盐虾酱在不同温度下贮藏的品质变化与货架期

对低盐虾酱在20℃、25℃、30℃、35℃下贮藏的品质变化与货架期进行了研究。通过检测贮藏期间菌落总数、副溶血性弧菌、挥发性盐基氮(TVB-N)的变化,并结合感官品质的变化,初步推测了在不同温度下贮藏产品的货架期,并对货架期终点的指标值进行了分析。结果表明:在20℃、25℃、30℃、35℃贮藏过程中,低盐虾酱货架期分别为100d、100d、80d、60d。各温度货架期终点时的菌落总数分别为3.8×104cfu/g、3.9×104cfu/g、4.1×104cfu/g、4.2×104cfu/g,TVB-N值分别为134.6mg/100g,146.8mg/100g,148.7mg/100g,153.6mg/100g,未检出副溶血性弧菌。在4种温度贮藏条件下,感官品质的变化主要是由微生物和化学变化导致的,其变化与菌落总数、TVB-N的变化趋势基本一致。     

冷冻处理的熟制虾肉在保鲜条件下的货架期

以熟制克氏原螯虾(Procambarus clarkia)虾肉为原料,分别进行缓慢冷冻和快速冷冻处理后,于4℃下贮藏,通过感官评价、理化指标和微生物指标的测定,研究冷冻处理的熟制虾肉的货架期和品质。研究发现:快速冷冻处理虾肉的品质优于缓慢冷冻处理,但两者的货架期均为5d,6d为可接受的限值,未经冷冻处理的虾肉货架期为2d。感官评分值与TVB-N,MDA含量和菌落总数均有极显著的负相关,R2均在-0.947以上(P<0.01)。快速冷冻组虾肉在贮藏期间失重率和pH值稳定。TVB-N和菌落总数有望作为评价熟制虾肉品质的化学指标,TVB-N值为30mg/100g和菌落总数为6logcfu/g可作为熟制虾肉可接受的限值。冷冻处理有效的延长了熟制虾肉在4℃贮藏条件的货架期,可作为一种处理手段应用于熟制水产品的保鲜。     

微酸性电解水对罗非鱼片保鲜效果的研究

为探讨微酸性电解水在罗非鱼加工应用的前景,开展微酸性电解水对罗非鱼片的保鲜效果研究。将罗非鱼片浸泡在有效氯浓度为(31. 39±1. 48) mg/L的微酸性电解水10 min后沥干装入聚乙烯保鲜袋,置于4℃下贮藏,以感官评定、挥发性盐基氮(total volatile base nitrogen,TVB-N)值、k值、菌落总数与p H等作为评价指标,测定罗非鱼片冷藏过程中的品质变化。结果表明,在贮藏期间,对照组样品TVB-N值2～3 d超过20 mg/100 g,而实验组样品第6天刚超过20 mg/100 g,对照组样品k值2～3 d超过60%,而实验组样品5～6 d超过60%,对照组样品菌落总数2～3 d超过6 lg CFU/g,而实验组样品第6天刚超6 lg CFU/g,实验组样品p H增加始终较对照组样品慢,而实验组样品感官评分始终高于对照组样品。采用微酸性电解水处理后的罗非鱼片,对比对照组货架期延长2～3 d。为微酸性电解水在水产品保鲜技术上应用提供技术参考和依据。     

鲅鱼贮藏过程中的品质变化和货架期预测

将感官、微生物和化学变化作为检测指标,对鲅鱼(Scomberomorus niphonius)在0℃、4℃、15℃、22℃和25℃贮藏过程中的品质变化和货架期进行研究。通过化学分析研究,对菌落总数(TVC)、挥发性盐基氮(TVB-N)、三甲胺(TMA)与感官评价的一致性进行探讨。结果表明,在0℃、4℃、15℃、22℃和25℃贮藏过程中鲅鱼较好品质的时期分别为192h、144h、24h、18h和12h,货架期终点分别为240h、192h、48h、24h和20h。各个温度条件下,鲅鱼贮藏过程中较好品质期和货架期终点的TVB-N平均值分别为(22.88±1.98)mg/100g、(49.40±2.40)mg/100g;TMA均值为(11.67±1.88)mg/100g、(18.88±2.75)mg/100g;菌落总数分别为(4.01±0.49)lg(CFU/g)、(6.17±0.49)lg(CFU/g);产H2S菌数分别为(3.28±0.63)lg(CFU/g)、(5.78±0.65)lg(CFU/g),、假单胞菌数分别为(3.60±0.39)lg(CFU/g)、(6.12±0.50)lg(CFU/g)。可知TVB-N、TMA、菌落总数、产H2S菌、假单胞菌作为鲅鱼贮藏过程中的鲜度指标与感官评价具有一致性。     

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.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

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