响应面法优化鱼皮胶原蛋白多肽螯合锌工艺

采用响应面法优化鱼皮胶原蛋白多肽与硫酸锌进行螯合反应的条件,制备胶原肽螯合锌产品.以胶原肽与硫酸锌的质量比、时间、温度和pH值4因素3水平进行Box-Behnken中心组合实验,运用Design-Expert7.0数据统计分析软件,建立螯合率的回归方程.结果表明,最佳螯合工艺条件为胶原肽与硫酸锌的质量比2.8∶1,时间33.2min,温度40.1℃,pH值7.3.在此条件下,螯合率为67.25％,与模型的预测值67.36％接近.紫外光谱检测结果初步显示,胶原肽与锌发生了螯合并产生了一种新型螯合物.     

白鲢鱼骨胶原多肽螯合钙的工艺优化

为减少淡水鱼加工过程中副产物对环境的污染和资源的浪费、提高淡水鱼的附加值,对白鲢鱼骨制备胶原多肽螯合钙的工艺进行研究。以白鲢鱼骨和氯化钙为原料,在一定条件下制备胶原多肽螯合钙,考察温度、鱼骨胶原多肽与氯化钙的质量比、时间、pH值对螯合率和螯合物中钙含量的影响。根据单因素试验结果,对胶原多肽螯合钙工艺进行四因子二次正交旋转设计优化,得到鱼骨胶原多肽螯合钙的最佳工艺参数为温度42 ℃、时间38 min、鱼骨胶原多肽与氯化钙的质量比2.1∶1、pH 6.8,此条件下的螯合率和螯合物中的钙含量分别为80.4%和12.1%。对螯合钙进行氨基酸组成成分分析,其总氨基酸含量为61.03%,且具备典型的胶原蛋白氨基酸组成特征。红外光谱扫描和电镜扫描观察表明：钙离子与胶原多肽发生了螯合反应,结合方式有离子结合、配位结合和吸附作用。     

丝素肽与锌螯合工艺条件的研究

研究了丝素蛋白水解物中的多肽与锌离子合成制备多肽-锌螯合物的工艺条件,探讨了反应液的pH、多肽液与锌的质量比、多肽浓度、锌盐来源、反应温度、反应时间对螯合反应的影响.通过正交实验确定了获得螯合物的最佳工艺条件是:反应液pH6,多肽与锌的质量比2:1,多肽液浓度0.05g/mL,反应温度50℃.此条件下,锌的螯合率为86.54%,螯合物得率为84.5%.     

鮟鱇鱼骨胶原多肽螯合钙的工艺优化

为减少水产品加工过程中副产物对环境的污染与资源的浪费、提高水产品的附加值,对鮟鱇鱼骨制备胶原多肽螯合钙的工艺进行优化。以鮟鱇鱼骨为原料,在适宜条件下制备小分子胶原多肽,并与鱼骨钙提取液进行螯合,制成胶原多肽螯合钙,分别考察螯合温度、鱼骨胶原多肽与鱼骨浸提液的质量比、时间、pH值对螯合率和螯合物中钙含量的影响。根据单因素试验结果,对胶原多肽螯合钙工艺进行四因素三水平正交试验,得到鮟鱇鱼骨胶原多肽螯合钙的最佳工艺参数为螯合温度30℃、时间50 min、鮟鱇鱼鱼骨胶原多肽与钙浸提液质量比2∶1、pH 6,此条件下的螯合率和螯合物中的钙含量分别为98.00%和21.29%。对螯合钙进行氨基酸组成成分分析,其中,具备典型的胶原多肽氨基酸的含量占总氨基酸含量的17.37%。     

猪皮胶原多肽螯合钙的制备及其结构表征

以猪皮明胶复合酶解胶原多肽和葡萄糖酸钙为原料,多肽钙螯合率为指标,在一定条件下制备多肽螯合钙。通过Plackett-Buiman(PB)和中心组合设计(CCD),考察胶原多肽/水料液比、多肽/葡萄糖酸钙质量比、p H、反应温度、反应时间、搅拌时间、搅拌速度等因素对多肽螯合率的影响。结果表明:通过PB设计筛选出多肽/葡萄糖酸钙质量比、p H和反应时间为多肽钙螯合主要影响因素,经CCD优化确定最佳螯合工艺为多肽/葡萄碳酸钙质量比5.5∶1,p H6.0,反应时间130 min,胶原多肽/水料液比1.5∶100,反应温度60℃,搅拌速度30 r/min,搅拌时间20 min。在此条件下,多肽螯合率达78.3%。采用紫外光谱、红外光谱、扫描电镜、X衍射等手段,研究了猪皮胶原多肽螯合钙的结构,结果表明猪皮胶原多肽与钙形成了螯合物,且胶原多肽的氨基和羧基均与Ca2+发生了螯合反应。     

罗非鱼多肽-Ca、Cu螯合工艺及其产物的结构特征

以罗非鱼多肽为原料,研究多肽与钙、铜金属离子在不同质量比、pH、温度和时间等条件下合成多肽-钙及多肽-铜螯合物的螯合反应工艺条件,并通过红外分析螯合物的结构特征。结果表明:pH和质量比是影响多肽-金属螯合反应的主要因素,制备罗非鱼多肽-钙螯合物和罗非鱼多肽-铜螯合物的适宜工艺分别为质量比4:1、pH9、温度45℃、时间45 min和质量比3:1、pH4.5、温度50℃、时间45 min,螯合率分别达43.06%和53.36%。     

小麦肽-锌螯合物的制备

研究了用谷朊粉水解物与锌离子制备多肽-锌鳌合物的工艺条件,探讨了反应液的pH、多肽液与锌的质量比、多肽浓度、锌盐来源、反应温度、反应时间对螯合反应的影响.通过正交试验确定了获得螯合物的最佳工艺条件为:反应液pH6、肽锌质量比2:1、反应温度70℃、多肽反应液浓度0.03g/mL、反应时间50min.此条件下,锌的螯合率和螯合物得率分别是84.25％、82.07％.     

利用废革屑制备不同分子量肽-Zn螯合物的工艺探究

本文主要通过不同用量的碱对废革屑进行水解,制备不同分子量的多肽1、多肽2、多肽3,利用GPC测定3种多肽分子量,并将多肽和Zn(CH3COO)2进行螯合反应来制备多肽-Zn金属螯合物。设计单因素实验,考察了pH、反应温度、反应时间、多肽-Zn质量比等因素对螯合反应的影响。确定了Zn(CH3COO)2与多肽螯合的最佳条件。多肽1的最佳螯合条件:多肽-Zn比为7∶1,反应时间60 min,反应温度为60℃,pH为8,最佳条件下的螯合率为66.83%;多肽2的最佳螯合条件:多肽-Zn比为7∶1,反应时间60 min,反应温度为60℃,pH为8,最佳条件下的螯合率为75.33%;多肽3的最佳螯合条件:多肽-Zn比为6∶1,反应时间60 min,反应温度为60℃,pH为7,最佳条件下的螯合率为82.56%;最后,对多肽-Zn螯合物进行红外光谱分析表征,结果表明Zn离子成功螯合到多肽上,得到Zn肽螯合物。     

鲢鱼源多肽锌的制备工艺对其抑菌活性的影响

研究了制备工艺中的主要因素对鲢鱼源多肽锌螯合物的抑菌活性影响。以抑菌圈直径为指标,探讨了酶解工艺(蛋白酶种类和酶解时间)和螯合工艺(螯合反应的pH、多肽与氯化锌的质量比、螯合反应的温度和时间)对多肽锌螯合物的抑菌活性影响。结果表明,酶法水解鲢鱼蛋白制备抑菌型多肽锌的最佳条件为风味蛋白酶酶解时间6h、螯合反应pH为6.0、多肽与氯化锌质量比为2:1、反应时间45min、温度30℃,得到的螯合物对大肠杆菌和金黄色葡萄球菌的抑菌圈直径分别为12.50mm和12.66mm,螯合物得率38.67%。因此,鲢鱼源多肽锌螯合物具有较好的抑菌活性,有望作为一种潜在的抗菌剂。     

蚕蛹多肽螯合钙的制备工艺优化及结构表征

利用蚕蛹多肽为原料制备多肽螯合钙,以可溶性钙含量为主要指标,综合考察螯合率和得率,研究了螯合pH、温度、时间以及肽钙比等单因素的影响,并进一步通过响应面优化法对制备工艺进行优化,确定最优的反应条件为反应时间80min、反应温度73℃、pH 10、肽钙质量比3.41.0,该条件下蚕蛹多肽螯合钙的含钙量为14.51%。傅利叶红外光谱分析表明蚕蛹多肽主要通过羧基、胺基和磷酸基团与钙离子结合。     

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.     

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.     

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.