氯化钙处理对牛肉系水力影响的研究

试验采用2因素有重复试验设计,研究对宰后8h的牛肉分别注射肉重3%的浓度为200mmol/L、250mmol/L、300mmol/L的CaCl2溶液,然后将处理样品在4℃下腌制12h、24h、48h,通过对其煮熟率的测定,分析注射CaCl2溶液及腌制时间对牛肉系水力的影响。试验结果表明:与对照组相比,不同浓度的CaCl2溶液处理对牛肉煮熟率影响差异不显著(P>0.05);不同腌制时间对牛肉煮熟率的影响差异亦不显著(P>0.05)。注射CaCl2溶液对牛肉的系水力无显著影响。     

注射氯化钙和 Vc对牛肉品质的影响

将宰后 8 h 的牛肉分别注射0、100、200 mmol/L 的氯化钙溶液和 0%、1%、2%的 Vc 溶液(注射量为肉质量的 5%),然后将肉样在 4 ℃下分别放置2、4、6 d,通过对其剪切力、pH、总色素进行测定,以研究注射氯化钙和 Vc 对牛肉嫩度、pH、总色素的影响.结果表明:氯化钙溶液处理显著影响牛肉的嫩度(P<0.05),但对pH和色泽的影响不显著(P>0.05);Vc 溶液处理显著影响牛肉的 pH(P<0.05),但对嫩度、色泽的影响不显著(P>0.05);Vc 和氯化钙对牛肉品质的影响没有互作效应.     

牛肉嫩化机制的初步研究

对牛肉分别注射300mmol／LCaCl2溶液、EDTA溶液、ZnCl2溶液（注射量为肉重的5％），然后将处理样品在4℃下分别腌制24h、48h，通过对其剪切力值、MFI的测定，初步研究牛肉嫩化的机制。结果表明，注射CaCl2能促进肌原纤维的分解，进而加速肉的嫩化；而注射EDTA和ZnCl2却抑制肌原纤维的分解，阻止肉的嫩化。牛肉的嫩化是Ca^2＋通过促进肌原纤维的分解而实现的。     

CaCl_2处理对羊肉嫩度和系水力的影响

选用宰后8h的羊背最长肌,注射占肉质量3%的浓度分别为0、150、200和250mmol/L的CaCl2溶液,将样品放在4℃左右冷藏24h后,测定其剪切力和煮熟率,以此分析不同浓度CaCl2处理对羊肉嫩度和系水力的影响。研究结果显示,CaCl2处理能显著降低羊肉的剪切力(P<005),但对煮熟率影响不显著(P>005)。注射CaCl2在改善羊肉嫩度同时,不影响羊肉的系水力。     

应用蛋白酶进行牛肉嫩化的研究

以牛肉为材料,研究不同嫩化液及重组等处理对牛肉的持水力值、pH值及色泽等指标变化的影响,旨在阐明牛肉嫩化机理,寻找适于对牛肉生产的嫩化方法和最佳物质组合,确定牛肉的最佳加工工艺。主要研究结果如下:在4℃条件下,不同嫩化液对牛肉嫩化的单因素试验显示:各种嫩化液都可不同程度地提高肉的嫩度,以0.03?Cl2溶液、40%木瓜液、60%苹果梨汁20 mL/100 g嫩化效果较好,对牛肉色泽均有显著影响;CaCl2溶液对pH值没有显著影响,但木瓜液和苹果梨汁对pH值均有一定影响。优化试验表明:牛肉嫩化效果的主次顺序为CaCl2溶液>木瓜液>苹果梨汁>腌渍时间,3种嫩化液组合注射,其CaCl2溶液、木瓜液、苹果梨汁浓度分别为0.03%、40%、20%,在4℃条件腌制时间为12 h,牛肉嫩化效果最佳。     

不同注射处理对牛肉剪切力和肌原纤维小片化指数的影响

本文研究了不同注射处理对牛肉在成熟过程中剪切力,肌原纤维小片化指数(MFI)的影响。3头改良黄牛(鲁西黄牛×犁木赞)在屠宰厂按照标准的屠宰工艺屠宰并预冷20h后取样,将样品给予7个不同的处理,每个处理分别按样品重10%注射蒸馏水(作为对照)、200mmol/L CaCl2、200mmol/L EGTA、200mmool/L ZnCl2、0.2mg/ml亮肽素、0.2mg/ml亮肽素 1%Triton X-100、1%Triton X-100,处理后将样品分别成熟3、8、16d后测一些指标变化。结果发现注射外源性钙激活酶抑制剂(亮肽素,ZnCl2)显著降低了牛肉的成熟速度,使牛肉剪切力增加,MFI降低;而注射CaCl2则相反,且注射CaCl2后牛肉成熟4d时的剪切力和对照组成熟16d时的差异不显著(p>0.05)。     

超声结合氯化钙溶液处理对牛肉品质的影响

探讨超声波结合氯化钙处理在不同成熟期对牛肉色泽、系水力、蒸煮损失及嫩度的影响。选择对宰后12h成年母黄牛的臀肉注射300mmol/L 氯化钙(注射量分别为肉质量的5%、10%),样品再分别在强度为133W/m2 的超声波中处理6、12min,即4 个处理组(Ⅰ组注射量5%、处理6min,Ⅱ组注射量5%、处理12min,Ⅲ组注射量10%、处理6min,Ⅳ组注射量10%、处理12min),对照组未作任何处理。各组分别在4℃成熟1、2、3、4、5、7d时检测肉块的色泽、系水力、蒸煮损失及嫩度(剪切力)。结果表明：注射10% 氯化钙结合超声波处理12min 对牛肉的色泽、系水力、蒸煮损失改善效果最好,注射5% 氯化钙结合超声波处理6min 对改善嫩度效果最显著(P ＜0.05),剪切力平均降低了28.41%。所以超声波结合氯化钙处理牛肉能明显改善牛肉品质。     

焦磷酸钠处理对牛肉嫩度和系水力影响的研究

向牛肉切块中注入10mmol／L、20mmol／L、30mmol／L3种不同浓度的焦磷酸钠（注射量占肉重0．3％）．然后在0～4℃条件下腌制24h，通过测定剪切力、煮熟率。分析不同浓度焦磷酸钠对牛肉嫩度和系水力的影响。结果表明，焦磷酸钠对牛肉剪切力影响极显著（P〈0．01）。牛肉嫩度有显著的改善作用；焦磷酸钠的适宜浓度为20mmol／L。焦磷酸钠处理对牛肉煮熟率的影响无显著差异（P〉0．05），焦磷酸钠处理对牛肉系水力无影响。     

可溶性胶原蛋白含量、肌原纤维小片化指数和粗钙激活因子活性的测定及其与牛肉嫩化效果之间的关系研究

本试验采用宰后向牛的股二头肌注射CaCl2溶液和木瓜蛋白酶来嫩化牛肉，并于后熟24h进行了肌原纤维小片化指数（MFI），粗钙激活因子活性（CAF）和可溶性胶原蛋白含量等指标的测定。实验结果表明，宰后注射CaCl2溶液和木瓜蛋白酶，显著降低了股二头肌的剪切力。3?Cl2溶液导致CAF活性比对照组显著增强。试样的可溶性胶原蛋白含量与剪切力相关性（r=-0.96)。对照组MFI与相应的剪切力相关显著（r=-0.736)。因此，MFI可作为量常规方法后熟或注射CaCl2牛肉的嫩度的方法。对于采用注射植物蛋白酶嫩化的牛肉，测量其可溶性胶原蛋白含量对于预测嫩度具有重要意义，而CAF活性的测定则可衡量常规方法后熟或注射CaCl2溶液的牛肉后熟的程度及其嫩度。     

注射CaCl2对猪半腱肌品质的影响

选用宰后48 h的猪半腱肌,注射占肉重5%、浓度分别为0和300mmol/L的CaCl2溶液,放在4℃左右条件下冷藏72 h后,测定其剪切力、煮熟率、pH和总色素,以此分析CaCl2处理对猪半腱肌品质的影响.结果显示,注射CaCl2能显著降低猪半腱肌的剪切力（P＜0.05）,但对煮熟率、pH和总色素影响均不显著（P＞0.05）.可见,注射CaCl2能通过改善猪半腱肌的嫩度而提高其品质,而对系水力、pH和色泽没有影响.     

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.     

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.     

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.     

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.     

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.