冰衣对冷冻南美白对虾贮藏品质的影响

通过测定－20 ℃冷冻条件下无冰衣组、15%镀冰衣组和25%镀冰衣组南美白对虾的感官评分、解冻损 失、蒸煮损失、挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量、盐溶蛋白含量及肌苷酸（inosine-5’- monophosphate,IMP）关联物各比值,研究镀冰衣处理对冻藏南美白对虾品质的影响。通过分析IMP关联物各比值 （K、Ki、G、P、H及Fr）与主要鲜度指标间的相关性,探讨更适宜作为－20 ℃冷冻条件下镀冰衣南美白对虾品质评 价的指标。结果表明：随着贮藏时间的延长,3 组南美白对虾的解冻损失、蒸煮损失和TVB-N含量均呈明显上升趋势, 盐溶蛋白含量显著下降,25%镀冰衣组南美白对虾的品质始终优于无冰衣组和15%镀冰衣组;根据各指标间的Pearson相 关性分析,K、Ki、G、P、H及Fr值中,K值更适合用于评价该贮藏条件下南美白对虾的整体质量;无冰衣组、15%镀冰 衣组和25%镀冰衣组分别在贮藏第12、16、16周感官不可接受,镀冰衣能够有效延长冻藏南美白对虾的贮藏期。     

不冻液冻结乌鳢块冻藏过程中品质变化

为了研究不冻液冻结对乌鳢块冻藏过程中冰晶及品质的影响,采用不同冻结温度（－20、－30、－40 ℃）的不冻液和空气冻结乌鳢块,以冰晶大小、盐溶性蛋白含量、pH值、挥发性盐基氮（total volatile basic nitrogen,TVB-N）含量、硫代巴比妥酸（thiobarbituric acid,TBA）值和持水性等为指标,考察了乌鳢块冻藏（－18 ℃）过程中的品质变化。结果表明：采用－20、－30、－40 ℃不冻液冻结的乌鳢块通过最大冰晶生成带的时间分别为310、226 s和125 s,生成冰晶的面积分别为308.8、142.4 μm2和86.5 μm2,分别显著短于和小于空气冻结方式下乌鳢块通过最大冰晶生成带的时间（3 412 s）和生成冰晶的面积（939.6 μm2 ）（P＜0.05）。另外,在－18 ℃冻藏过程中,经不冻液冻结的乌鳢块的盐溶性蛋白含量均明显高于空气冻结组,而形成冰晶大小、pH值、TBA值、TVB-N含量、汁液流失率和蒸煮损失率均明显低于空气冻结组,其中－40 ℃不冻液冻结后的乌鳢块在冻藏过程中品质变化最小。综合以上结果,不冻液冻结比空气冻结能够更好地保持冻藏过程中乌鳢块的品质,且不冻液的冻结温度越低,冻结速率越高,形成冰晶越小,越有利于鱼肉品质的保持。     

冻结及冻藏温度对小龙虾品质的影响

为探究冻结及冻藏温度对小龙虾品质的影响,将小龙虾热烫后置真空包装盒内,灌水并抽成真空,分别于3个冻结温度(-20,-40和-55℃)的冰柜内冻结至中心温度为-15℃,再置于2个冻藏温度(-20,-40℃)的冰柜中冻藏24周,测定小龙虾的汁液流失率、持水率、剪切力、pH值、TVB-N值、水分状态和肌肉组织的显微结构。结果表明:-20℃与-40℃和-55℃两种冻结温度的小龙虾肌肉组织对比,其肌纤维被破坏程度较轻,虾肉持水率较高,汁液流失率、剪切力、pH值、TVB-N值较低。与-40℃相比,在-20℃冻藏的小龙虾的肌纤维完整性较低,孔隙较大,结构从紧密变成松散,虾肉的持水率、结合水和不易流动水含量较低,汁液流失率、剪切力、自由水含量、pH值和TVB-N值均较高。结论:冻结及冻藏温度影响小龙虾的品质。     

南美白对虾肉糜低温冻藏过程中蛋白质的特性变化

研究南美白对虾肉糜在冻藏过程中的蛋白质特性变化。以虾仁为对照组,主要考察冻藏第0、20、40、60、80、100、120d时在虾仁和虾糜中的pH值、Ca~(2+)-ATPase酶的活性、疏水键、二硫键、水溶性和盐溶性蛋白含量、离子键和巯基类等指标的变化。随着冻藏时间的延长,虾仁和虾糜的pH值,疏水键和二硫键的值都处于升高状态,但是虾糜组的指标都比虾仁低,冻藏120 d的虾糜组分别比虾仁组低0.18、3.28、2.64mg/g;在水溶性和盐溶性蛋白含量、Ca~(2+)-ATPase活性、总巯基、活性巯基、离子键的含量等方面各组数据都处于下降状态,但是虾糜的下降幅度比虾仁小。虾糜组的离子键、水溶性和盐溶性蛋白含量在冻藏120 d后分别比虾仁组高3.62、12.14、5.73 mg/g。在120 d时虾仁的肌原纤维蛋白含量降至新鲜虾仁的38.21%,而虾糜的含量降至43.36%。这表明在冻藏过程中,虾糜的储存形式比虾仁的储存形式更有利于对虾品质的贮藏。本研究的研究结果为虾糜的蛋白等理化品质鉴定提供了理论基础,同时也为虾类产品的精深加工提供了科学依据。     

鲍鱼冻藏过程生化及感官指标变化研究

研究-20℃和-80℃两种冻藏温度下,鲍鱼的生化特性、菌落总数、水煮感官指标等的变化。结果表明:两组鲍鱼解冻失水率呈现上下波动趋势,未发现明显差异。-80℃下冻藏鲍鱼的pH值上升速度低于-20℃时的pH值;解冻后的含水量明显高于-20℃时;TBA值比-20℃时低,且差异达极显著水平(P<0.01)。冻藏至90d时,-20℃冻藏鲍鱼的TVB-N较-80℃时高2.12mg/100g;而ATPase活性较-80℃低5.02μg/mL;-80℃冻藏鲍鱼菌落总数较-20℃时降低43.16%。从水煮后的汤汁香气、色泽、味道及鲍鱼肉口感等分析,-80℃冻藏鲍鱼各项感官指标均优于-20℃时。方差分析表明,除鲍鱼肉口感差异不显著外,其余感官指标均差异显著(P<0.05)。综上所述,-80℃冻藏可大大延缓鲍鱼的品质下降,抑制微生物的生长,延长鲍鱼的货架贮藏期,提高鲍鱼的冻藏品质。     

鸡胸肉冻藏温度下的理化和感官特性变化研究

系以p H值、水分活度、色泽、主成分分析、质构特性为理化指标并结合感官评价,探究鸡胸肉在-20、-40℃和-80℃不同冻藏温度下的变化规律。结果表明:在-20℃冻藏温度下,鸡胸肉的pH值随时间的延长呈先上升后下降的趋势,在-40℃和-80℃时pH值逐渐上升;在冻藏过程中,随着冻藏时间的延长,鸡胸肉的水分活度值、a*值、b*值、硬度、弹性和粘聚性均呈下降趋势,而L*值呈上升趋势;鸡胸肉的感官评分随冻藏时间的延长均呈下降的趋势。综合来看,冻藏温度越低,冻藏时间越短,越有利于鸡胸肉的保藏。     

盐藻多糖对熟制南美白对虾冻藏期间品质变化的影响

研究了0.06%盐藻多糖处理对冻藏南美白对虾品质的影响。以菌落总数、TVB-N值、TBA值、色差(L~*、a~*和b~*)、质构(硬度和弹性)和水分含量作为评价指标,分析盐藻多糖处理对冻藏对虾新鲜度和品质的影响。结果表明,熟制南美白对虾冻藏期间新鲜度没有超标,但虾体水分含量降低幅度较大,硬度迅速增加,弹性降低,L~*、a~*和b~*值降低,对虾整体品质随着贮藏时间的增加而下降。盐藻多糖处理提高了对虾的新鲜度,且保持了虾体水分,改善了对虾的硬度和弹性,抑制了对虾褪色,起到了一定的保水和护色作用。     

冻结速率对凡纳滨对虾虾仁贮藏特性的影响

本文以凡纳滨对虾（Penaeusvannamei）虾仁为原料,分别采用-80℃和．20℃两种冻结条件对虾仁进行冻结处理,分析冷冻速率对凡纳滨对虾虾仁贮藏过程中理化、鲜度及色泽特性的影响,明确冻结速率对虾仁解冻后的质量变化特征的影响规律。总体来讲,冻藏过程中虾仁质量变化趋势基本一致,随着冻藏时间的延长,虾肉解冻损失率增加,鲜度降低,pH呈下降后上升的趋势,TVB-N值上升,产品的亮度指标L＊升高。冻结速率对虾仁的贮藏特性影响差异显著,冻藏6d后冻结速率对虾仁解冻损失率、鲜度指标影响出现分化,-80℃速冻处理可明显改善虾仁的解冻失水,保证虾仁鲜度。20d后,pH值、TVB-N值变L‘值变化情况也表明-80℃速冻在一定程度上可以减轻虾仁贮藏过程中的质量劣化程度。     

液氮冻结温度对冻藏黄鳝脂质氧化和气味变化的影响

目的 探讨液氮冻结温度对冻藏黄鳝脂质氧化和气味变化的影响。方法 测定液氮冻结(?50、?80、?110℃)和?20℃冰柜冻结(对照)的冻藏黄鳝的脂质和游离脂肪酸(free fatty acids, FFAs)含量、过氧化值(peroxide value, POV)、硫代巴比妥酸反应物(thiobarbituric acid reactive substances, TBARs)、脂肪酸组成、挥发性气味物质, 并进行感官评价。结果 随着冻藏时间的延长, 整体上4种温度条件下黄鳝的脂质、单不饱和脂肪酸(monounsaturated fatty acids, MUFAs)和多不饱和脂肪酸(polyunsaturated fatty acids, PUFAs)含量显著下降(P<0.05), FFAs、POV、TBARs值及饱和脂肪酸(saturated fatty acids, SFAs)含量显著上升(P<0.05)。液氮冻结黄鳝的脂质、MUFAs、PUFAs含量和感官评分高于对照, ?80℃和?110℃液氮冻结黄鳝的FFAs、SFAs含量显著低于?50℃液氮冻结和对照(P<0.05); ?80℃和?110℃液氮冻结黄鳝的脂质氧化差异基本上不显著(P>0.05)。气相色谱-离子迁移谱法检测出25种挥发性气味物质。此外, 液氮冻结温度越低, 冻藏黄鳝的正己醛和正丙醛相对含量越低。结论 降低液氮冻结温度能够显著抑制冻藏黄鳝的脂质氧化和气味变化, 有效保护黄鳝的品质。     

干冰冻结对大黄鱼冻藏期间冰晶及品质的影响

目的:考察冻结方式及冻藏温度对大黄鱼贮藏过程中品质的影响。方法:采用干冰冻结和-40℃空气冻结新鲜大黄鱼鱼片至中心温度-18℃,然后分别置于-40,-18℃冰柜贮藏。测定大黄鱼冻结后和冻藏过程中冻结曲线、冰晶形态、pH值、挥发性盐基氮、K值、Ca²⁺-ATP酶活性、总巯基、羰基、蛋白降解、质构特性等理化指标。结果:干冰冻结通过最大冰晶生成带的时间为40 min,是-40℃空气冻结的1/6,干冰冻结鱼肉样品初始冰晶横截面积和当量直径分别为(96.12±1.61)μm²和(11.06±1.43)μm,显著低于空气冻结的鱼肉样品。结论:冻藏温度对鱼肉肌原纤维蛋白的影响要大于冻结温度，且冻藏温度越低，鱼肉肌原纤维蛋白降解程度越低。干冰冻结后-40℃贮藏有利于保持大黄鱼的鲜度和品质稳定性。     

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