冰温条件下贮藏军曹鱼最佳气调包装参数的研究

在冰温下贮藏,研究不同的包装条件对军曹鱼品质的影响,确定冰温气调包装军曹鱼最佳气调包装参数。对照组为空气贮藏,实验组气体配比为6组,分别为100%N2、75%N2+25%CO2、50%N2+50%CO2、30%N2+65%CO2+5%O2、25%N2+75%CO2、100%CO2,包装袋以纯PE、一般阻隔性、高阻隔性3种材质的包装材料为对象进行研究,气调包装后在冰温袋-1.01~0℃范围内贮藏,贮藏期间考察K值、挥发性盐基氮(TVB-N)含量、细菌总数和汁液流失率等品质指标的变化。结果表明,K值、TVB-N含量、细菌总数、汁液流失率均在贮藏期间有不同程度的增加,并且对照组和实验组有显著性差异(p<0.05),以K值、TVB-N含量、细菌总数增长速度慢,汁液流失率少为评定标准,综合比较几种品质指标的变化规律,最终确定为使用高阻隔性包装袋并充以50%N2+50%CO2的气体配比进行冰温气调包装军曹鱼为最佳。     

不同CO_2比例气调包装对冰温贮藏鲜罗非鱼片品质的影响

采用不同的气体组成A(50%CO2/10%O2/40%N2)、B(60%CO2/10%O2/30%N2)、C(70%CO2/10%O2/20%N2)和空气(对照)分别包装鲜罗非鱼片,在-0.5±0.2℃贮藏,研究不同CO2比例气调包装在冰温贮藏条件下对鲜罗非鱼片品质的影响。实验结果表明,罗非鱼的冰点在-0.8～-0.9℃之间,贮藏7d以后,与对照相比,气调包装能显著抑制产品细菌菌落总数和嗜冷菌数的增长(p<0.05)。在冰温贮藏期间,气调包装样品的肉汁渗出率要高于对照产品,随着贮藏时间的延长,四组样品的TVB-N值均有不同程度的上升,但是贮藏10d以后,对照的TVB-N值开始高于三种气调包装样品;包装方式对产品pH的影响并不明显,但是对照的pH随着贮藏时间的延长基本呈上升趋势,四种处理的罗非鱼片在整个贮藏期间TBA值几乎都没有变化。三组CO2比例气调包装样品在贮藏期间的品质差异并不明显,但是在冰温条件下,气调包装处理能明显延长鲜罗非鱼片的货架期。     

包装方式对冰温贮藏鳙鱼头鲜度的影响

以臭氧水减菌化处理的鳙鱼头为原料,研究采用真空(Ⅰ)、30%N2+70%CO2(Ⅱ)、45%N2+55%CO2(Ⅲ)、60%N2+40%CO2(Ⅳ)4种不同包装方式的鳙鱼头在冰温贮藏期间鲜度的变化,对其细菌总数、TBA值、TVB-N含量、K值、感官进行测定,以探讨包装方式对冰温贮藏鳙鱼头鲜度变化的影响。结果表明:包装方式对冰温贮藏期间鳙鱼头的鲜度变化具有显著性的影响,充气包装冰温贮藏的效果比真空包装冰温贮藏效果好。在3种充气包装中,比较适宜的充气比例为30%N2+70%CO2混合气体包装,鳙鱼头保鲜期较长。采用30%N2+70%CO2混合气体包装鳙鱼头在冰温(-1±0.5)℃条件下贮藏15d时,鳙鱼头的TVB-N值含量为11.37mg/100g,细菌总数1.83×105CFU/g,保鲜期比真空包装鳙鱼头延长了3d。     

冰温和冷藏对气调包装鱼糜制品品质的影响

为研究冰温冷藏温度对气调包装鱼糜制品(鱼丸)品质的影响,分别以-2℃冰温、0、3℃冷藏气调包装鱼丸,测定了鱼丸的菌落总数、TVB-N值、pH、感官和质构等品质的变化.结果表明:在-2℃冰温条件下,气调包装鱼丸的细菌受到更好地抑制,其TVB-N值、pH、感官、质构等品质指标均优于0、3℃冷藏下的鱼丸.-2℃冰温、0、3℃冷藏对鱼丸品质的保鲜效果优劣依次为-2℃ ＞0℃ ＞3℃,对应货架期分别为35、21、14d.-2℃的冰温结合气调包装对鱼丸有较好的保鲜效果;与3℃的冷藏条件相比,冰温能够更好地维持气调包装鱼丸的品质,从而延长其货架期.     

不同气调包装对醉虾贮藏品质的影响

研究了40%CO2+60%N2和100%CO2的气调包装以及真空和空气包装4种包装方式对贮藏醉虾菌落总数、理化指标和感官指标的影响。结果表明:相对于真空和空气包装组,100%CO2或40%CO2+60%N2的气体包装,对醉虾的保鲜效果较好,其样品的菌落总数和挥发性盐基氮含量较低,质地和色泽变化较小,感官评分较高。但由于100%CO2包装随着贮藏时间的延长,气体收缩较明显导致产品包装外观不理想,40%CO2+60%N2的混合气体包装更适合于醉虾的贮藏。     

养殖大黄鱼气调包装保鲜工艺研究

通过感官评定、微生物和理化分析,评价不同气体(空气、真空)包装以及不同气体比例的气调包装(30%CO2/70%N2、60%CO2/40%N2、75%CO2/25%N2)对养殖大黄鱼冷藏(4℃±1℃)保鲜效果的影响。试验结果表明:气调包装能明显延缓养殖大黄鱼的腐败变质,延长货架期,并保持良好的品质,尤以贮藏初期的保鲜效果较好;在冷藏(4℃±1℃)条件下养殖大黄鱼气调包装最适气体配比为75%CO2/25%N2,其货架期可达15 d,比空气包装延长了8 d。     

气调包装军曹鱼片在冰温保鲜期间的品质变化分析

为了探明气调包装军曹鱼片在冰温保鲜期间的品质变化,本文以空气包装和真空包装为对照,研究了气调包装军曹鱼片在冰温贮藏期间的K值、细菌总数、TVB-N、pH值、持水性、汁液流失率、感官评价、质构等品质指标的变化规律。结果表明:气调包装鱼片的鲜度指标K值达到初期腐败值60%和细菌总数的最大限值106 CFU/g是18 d,比空气包装和真空包装分别延长了6 d和2 d,达到TVB-N含量最大限值0.30 mg/g是23 d,比空气组和真空组延长了9 d和7 d。气调包装样品的汁液流失率、pH值升高速度较对照组缓慢;气调包装鱼片的持水率、感官品质、质构参数、色泽的变化较对照组小。综合比较表明,冰温气调包装军曹鱼片比空气包装和真空包装分别延长了8~10 d和2~6 d的贮藏期,说明冰温气调包装具有较明显的延缓军曹鱼片的腐败变质,更适合应用于高品质军曹鱼片的保鲜贮藏。     

模拟蟹肉复合保鲜技术研究

评价生物保鲜剂（水溶性壳聚糖0.4%+食用级植酸0.04%）结合气调包装（75%CO2+25%N2）和冰温〔（-2±0.5）℃〕贮藏的复合保鲜技术对模拟蟹肉的保鲜效果。通过测定样品的菌落总数、理化指标和感官指标及其与贮藏时间的相关性,分析V₁（真空包装）、V₂（真空包装+保鲜剂）、M1（气调包装）和M₂（气调包装+保鲜剂）等处理方式对冰温贮藏条件下模拟蟹肉品质的影响。结果表明,模拟蟹肉冰点为（-3.4±0.5）℃,添加保鲜剂后冰点基本不变。冰温贮藏模拟蟹肉的合适温度为（-2±0.5）℃。模拟蟹肉贮藏至56d时,各组样品的菌落总数都小于1 logCFU/g,保持良好的感官品质。贮藏至70d时,V₁组样品菌落总数为3.32logCFU/g,其它3组样品的菌落总数均小于1logCFU/g。贮藏70d后V₂、M₁和M₂组样品细菌总数均呈明显的上升趋势。经综合评定,冰温贮藏条件下V₁样品的货架期为84d左右,M₁和M₂样品的货架期为98d左右,V₂样品的货架期最长,可达到100d以上。研究结果显示复合保鲜技术可明显抑制腐败菌的繁殖,延缓感官品质的下降,在模拟蟹肉产业化中显示了良好的实际应用前景。菌落总数、硬度、胶着性的变化与贮藏时间呈显著正相关,感官评分、凝聚性、回复性与贮藏时间呈显著负相关。将这些指标作为反映模拟蟹肉品质变化的指标。而pH、TVB-N、白度在贮藏期变化不大,不适合作为反映模拟蟹肉品质变化的指标。     

气调包装对太平洋牡蛎冷藏保鲜效果的研究

研究了气调包装(60%CO2/40%N2、60%CO2/30%N2/10% O2)对太平洋牡蛎的气调保鲜效果.以空气包装组为对照,通过感官评定、pH、TVB-N、需氧菌数几项指标来评价气调包装的牡蛎样品在冷藏务件下(4±1℃)的贮藏效果,并对对照组和气调包装组的腐败样品进行了细菌菌相分析.实验结果表明,气调包装有效延长了牡蛎的冷藏货架期,对照组、CO2/N2组和CO2/N2/O2组的赁架期分别为6～7d、9～10d和11～12d.货架期终点时,对照组牡蛎样品以革兰氏阴性菌为主,其中假单胞菌(Pseudomonas)比例高达55%,是常规包装牡蛎冷藏的特定腐败菌;气调包装组样品以革兰氏阳性菌为主,其中CO2/N2组的优势菌为乳酸菌(Lactic acid bacteria),CO2/N2/O2组的优势菌为棒状杆菌(Corynebacterium).     

不同气调包装结合冰温贮藏对羊肉保鲜效果的影响

为延长鲜羊肉的保鲜时间,研究不同气体组分的气调包装对羊肉冰温贮藏过程中品质的影响。以真空包装为对照,比较75% O2＋25% CO2、75% N2＋25% CO2气调包装羊肉在－1 ℃冰温条件下贮藏过程中感官品质、色泽、汁液流失率、嫩度、挥发性盐基氮、pH值、微生物等品质指标的变化。结果表明：真空包装羊肉的汁液流失率显著高于2 种气调包装,而75% N2＋25% CO2气调包装羊肉的色泽和感官评分最差。75% O2＋25% CO2气调包装的保鲜效果最好,其色泽和感官评分最高,汁液流失率较小,pH值最低,－1 ℃冰温条件下贮藏42 d时,羊肉的菌落总数、假单胞菌菌数、乳酸菌菌数的对数值分别为5.91、5.95、5.23 （lg（CFU/g））,其中菌落总数指标符合国家二级鲜肉标准。因此,－1 ℃冰温条件下结合75% O2＋25% CO2气调包装可以使羊肉有效保鲜42 d,是较好的鲜羊肉保鲜方法。     

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.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

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.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

低温带皮菜籽粕微粉的不同粒级部分的功能特性

为研究低温带皮菜籽粕微粉的不同粒级部分的功能特性,以经低温脱脂的带皮菜籽粕为原料,经微粉碎后筛分成212~425μm、150~212μm和106~150μm的3个不同粒级的微粉样品,检测这些样品的吸水性、吸油性、乳化性和乳化稳定性、蛋白质体外消化率。结果表明:1 3个不同粒级的微粉样品之间的粗纤维含量存在显著差异,表明三者的结构组成成分有一定差异。23个微粉样品的乳化活性和乳化稳定性随粒度级别的减小而显著增加(P0.01)。33个微粉样品的蛋白质体外消化率随粒度级别的减小而显著增加(P0.01)。4不同粒级带皮菜籽粕微粉样品的吸水性与吸油性受其结构组成物质不同和粒度的双重影响,与粒度的相关性不明显。     

Microbiology of food taints

Fresh and processed foods are often spoilt by the presence of undesirable flavours and odours caused by microbial action. The aim of this paper is to review the current knowledge of microbiologically induced taints that occur in a wide range of foodstuffs, including meats, poultry, fish, crustaceans, milk, dairy products, fruits, vegetables, cereals and cereal products. Examples have been chosen where the compounds responsible for the taint have been identified and sufficient data obtained to demonstrate the involvement of microorganisms. However, in some cases the full identity of the causative organism may not have been elucidated. The types of microorganisms covered by this review include bacteria, fungi, yeasts, actinomycetes and cyanobacteria. Although cyanobacteria do not in general infect foods, their presence in aqueous systems and water supplies can lead to off-flavours in aquatic organisms and processed foodstuffs. Several examples of each of these processes are discussed. Wherever possible, the likely biosynthetic pathway used by the microorganism to produce the offending compound in a foodstuff is indicated.