复配生物涂膜保鲜液对冷藏南美白对虾的保鲜效果研究

目的探究复配生物涂膜保鲜液对冷藏南美白对虾的保鲜效果。方法以新鲜南美白对虾为原料,通过单因素实验考察壳聚糖、海藻酸钠、明胶及乳酸链球菌素(Nisin)对冷藏南美白对虾货架期的作用。在此基础上优化壳聚糖、海藻酸钠及Nisin所组成的复配涂膜保鲜液的最适配比。结果壳聚糖6 g/L、海藻酸钠8 g/L、Nisin 0.4 g/L组成的最佳配比复合保鲜液涂膜南美白对虾后冷藏保存,冷藏期限可以达到12 d,测得pH值为7.52,感官评分为3分,比对照组延长了6 d。结论南美白对虾涂膜复合保鲜液后,更能隔绝外界接触,抑制细菌繁殖,从而延缓虾肉的腐败变质,具有更好的保鲜效果,为进一步研究南美白对虾货架期与特定腐败微生物关系奠定理论基础。     

复合保鲜涂膜液对冷鲜牦牛肉保鲜及抗氧化效果的影响

本研究选用壳聚糖、茶多酚和乳酸链球菌素(Nisin)作为保鲜涂膜液,对牦牛肉保鲜进行了探讨。首先对单一防腐剂的保鲜效果进行评价,在此基础上,采用L9(34)正交实验法以菌落总数对数值、挥发性盐基氮值(TVB-N)和硫代巴比妥酸值(TBARs)为筛选指标,筛选出最佳复合保鲜涂膜液配比。结果表明:最佳复合保鲜涂膜液配比为壳聚糖0.9 g/100 m L,茶多酚0.9 g/100 m L,Nisin 0.005 g/100 m L,处理过牦牛肉第16 d时菌落总数对数值、TVB-N值、TBARs值、p H、感官评分值分别为(5.15±0.29)CFU/g、(9.05±2.01)mg/100 g、(0.274±0.018)mg/kg、(5.54±0.07)、(8.47±0.32)分,均显著低于(或高于)对照组(p0.05),仍具有一级新鲜度,能够有效延长冷鲜牦牛肉的货架期。     

3种天然保鲜剂对凤尾菇的保鲜效果

目的:研究肉桂精油、壳聚糖和抗坏血酸3种天然保鲜剂对凤尾菇储藏过程中的保鲜效果。方法:以新鲜凤尾菇为研究对象,分别采用不同浓度肉桂精油、壳聚糖和抗坏血酸对凤尾菇进行处理,结合感官评价找出3种保鲜液的最佳浓度,并研究不同浓度保鲜剂的凤尾菇在5 ℃贮藏过程中感官评价、呼吸强度、褐变度和腐烂指数的变化规律。接着通过正交试验,以3种不同浓度的保鲜剂为考察因素,感官评价与失重率为指标,选出保鲜效果最佳的复合保鲜剂配方。结果:单一涂膜处理时,肉桂精油1.5 g/L、壳聚糖15 g/L和抗坏血酸1.0 g/L具有最好的保鲜效果。最佳的复合保鲜剂配方为,肉桂精油浓度为1.0 g/L、壳聚糖浓度为15 g/L和抗坏血酸浓度为1.0 g/L,该复合保鲜液处理凤尾菇贮藏9 d,感官评分为(78±3)分,失重率为6.98%±0.43%。结论:此复合保鲜液对凤尾菇的保鲜能起到更明显的效果,贮藏期间凤尾菇的品质和色泽均较好。     

魔芋葡苷聚糖复合涂膜对樱桃保鲜效果研究

以汉中西乡樱桃为试材,研究魔芋葡苷聚糖(KGM)复合涂膜结合低温保藏对樱桃贮藏保鲜效果的影响。结果表明:以KGM6g/L,明胶1.0g/L,柠檬酸0.5%,山梨酸钾0.1%,山梨醇0.03%,VC0.1%,CaCl22%配制的涂膜液涂膜樱桃后的保鲜效果最好,可显著降低果实的失重率、腐烂指数、呼吸强度,延缓果实VC、总酸、可溶性固形物含量的下降。在(4±0.5)℃可贮藏9d。     

壳聚糖/氧化石墨烯复合涂膜食品包装纸的研究

为改良壳聚糖在食品包装中应用存在的机械性能不强,溶解性较差等缺陷,通过流延涂膜法,将壳聚糖/氧化石墨烯复配涂膜至食品包装纸,经抗氧化性、拉伸强度及水蒸气、油脂透过率等指标,对复合涂膜食品包装纸性质进行评估,结果发现采用酸溶性壳聚糖(18 m L,10 mg/mL)与氧化石墨烯(1 m L,1 mg/mL)再加入氧化剂(1 mL,1 mg/mL)制备得到的涂膜液复合涂膜食品包装纸,具有良好的保鲜功能,并初步探索壳聚糖/氧化石墨烯复合涂膜食品包装纸对生鲜猪肉贮藏保鲜过程中颜色、弹性、球蛋白沉淀、汁液流失率、蒸煮损失率的影响。与仅用壳聚糖处理的食品包装纸保鲜功能比较,壳聚糖/氧化石墨烯复合涂膜食品包装纸具有较好的保鲜效果。本研究结果为开发来源丰富、天然、无毒,具有优良性能的高效天然生物保鲜剂和保鲜材料提供理论依据。     

魔芋葡甘聚糖复合膜液对樱桃番茄的保鲜效果

以樱桃番茄为研究对象,研究魔芋葡甘聚糖(KGM)与乳酸链球菌素(Nisin)复合膜液对樱桃番茄的保鲜效果。分别采用不同浓度的KGM (3, 6和9 g/L)与Nisin (0.09 g/L)复合膜液对樱桃番茄进行涂膜处理,以无菌水处理为对照,处理后的樱桃番茄在室温(25℃)下贮藏,并定期测定其腐烂指数、失重率、可溶性固形物含量、硬度和过氧化物酶(POD)活性。结果表明, KGM-Nisin复合膜液涂膜处理能明显降低樱桃番茄的腐烂指数和失重率,有效减缓可溶性固形物含量和硬度的损失,能诱导POD活性维持在相对较高水平,其中,经6 g/L KGM与0.09 g/L Nisin复合膜液涂膜处理樱桃番茄的保鲜效果最好,说明涂膜处理能有效延缓樱桃番茄果实品质下降,为KGM-Nisin复合膜液在果蔬保鲜上的应用提供理论依据。     

魔芋葡甘聚糖复合涂膜对鲜切莲藕保鲜效果的影响

采用正交试验研究魔芋葡甘聚糖、黄原胶、植酸复合涂膜处理对鲜切莲藕保鲜效果的影响,筛选出保鲜效果较优的组合质量浓度,并进行验证实验。结果表明,较优的组合为15 g/L魔芋葡甘聚糖、1.5 g/L黄原胶、0.5 g/L植酸,在此条件下魔芋葡甘聚糖复合涂膜能有效抑制鲜切莲藕表面的褐变,降低呼吸强度,减少营养物质VC和可溶性固形物损失,并且可抑制其酚类物质含量的下降以及提高抗氧化能力,具有良好的保鲜效果。     

海藻酸钠复合膜对鲜切贡梨贮藏品质的影响

以海藻酸钠、明胶和山梨酸钾为涂膜材料,按照L9(33)正交试验制作不同配比的海藻酸钠复合膜,涂膜鲜切贡梨,在(0±0.5)℃条件下进行贮藏保鲜.结果表明,海藻酸钠复合涂膜能显著降低贮藏过程中鲜切贡梨的褐变指数、抑制呼吸速率,减少TA及Vc的损失;海藻酸钠的保鲜效果达到显著水平(P＜0.05);海藻酸钠复合膜的最佳配比为海藻酸钠0.05 g/kg、明胶0.03 g/kg、山梨酸钾0.03 g/kg.     

海藻酸钠/纳米TiO_2复合涂膜对香菇采后品质的影响

为探讨海藻酸钠/纳米TiO2复合物(SANT)涂膜处理对香菇的保鲜效果,考察了4℃条件下1.5%复合溶液涂膜处理对香菇品质和生理的影响。试验结果表明:SANT较对照组能更好地维持香菇的感官品质,减缓其水分散失,抑制呼吸强度,并保持较高的VC、总酚含量,对可溶性蛋白含量则无显著影响。此外,SANT较之于单独使用海藻酸钠涂膜能更好地控制微生物的生长。SANT处理对香菇的保鲜具有潜在的应用前景。     

银杏叶提取物/阿拉伯胶复合涂膜对草莓保鲜效果的影响

本研究采用不同浓度（0.25、0.50、0.75 mg/mL）的银杏叶提取物（Ginkgo biloba leaves extracts,GBLE）与100 mg/mL阿拉伯胶（gum arabic,GA）复合配制保鲜液，通过测定贮藏期间草莓感官品质、失重率、可滴定酸含量、可溶性固形物含量、Vc含量、硬度、腐烂率以及丙二醛含量的变化，探究GA-GBLE复合涂膜对草莓果实的保鲜效果。研究表明：单一GA涂膜和GA-GBLE复合涂膜较CK组相比对草莓保鲜效果均有显著性差异，均能显著的延缓草莓果实的感官品质、可滴定酸含量、可溶性固形物含量、Vc含量和硬度的下降，有效缓解失重率、腐烂率、丙二醛含量的上升。其中GA-GBLE复合涂膜液保鲜效果优于单一GA涂膜，且GA-0.50 mg/mL GBLE复合涂膜液保鲜效果最佳，可有效延缓草莓的贮藏期。因此，阿拉伯胶/银杏叶提取物复合涂膜作为保鲜剂，在果蔬贮藏保鲜方面具有一定的参考价值。     

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.