荞麦醋摇床醋酸发酵条件的研究

利用摇床进行荞麦醋的醋酸发酵.探讨了不同接种量、发酵液酒精度、发酵温度、摇床转速和瓶装量对发酵的影响.在单因素试验的基础上,选取发酵温度、摇床转速和瓶装量三个因素进行正交试验.研究结果表明:最佳产酸条件为温度30℃,转速90 r/min,装量1/4;最佳酒精转化条件为温度28℃,转速150 r/min,装量1/4.产酸速度和酒精转酸率分别达到0.328 g/L·h和76％.     

枯草芽孢杆菌工程菌株产普鲁兰酶发酵条件的优化

利用基因工程手段获得的产长野芽孢杆菌普鲁兰酶的枯草芽孢杆菌基因工程菌株WB600/pWB-pulB,通过单因素筛选及正交试验进行发酵培养基优化,得到产酶最佳配方为玉米淀粉3.0％,酵母膏20％,CaCl20.03％,Na2HPO41.0％.同时对重组菌株摇瓶条件下液体发酵的主要影响因素初始pH、接种量、装液量、转速、温度等进行探讨,确定了产酶最佳培养条件为,以3％接种量接种于优化后培养基,初始pH7.0,装液量30 mL/250 mL,37℃,200 r/min摇床培养36 h.在此优化条件下,普鲁兰酶活力达到20.16 U/mL,是之前研究结果(10.94 U/mL)的1.84倍.     

拐枣醋的工艺研制

文章以拐枣为原料酿造果醋,开发一种新型的保健果醋.通过单因素试验和正交试验对发酵温度、初始酒精浓度、醋酸菌种接种量、通风量进行了考察,优化得到的最佳工艺条件为:发酵温度34℃、接种量10％ (V/V)、初始酒度10％ (V/V)、通风量200 r/min(以摇床转速计),酿造得到具有浓郁的拐枣香气的新型保健果醋.     

二年残孔菌发酵条件优化研究

二年残孔菌摇瓶发酵较佳条件:最优培养基,葡萄糖38.08g/L,酵母浸粉8.54g/L,KH2PO4∶MgSO4=1∶1为4.25g/L,最优培养条件为温度30℃,500mL三角瓶装液量150mL,初始pH值为5,摇床转速180r/min,10％接种量的培养9d,达到最大产量15.5g.发酵罐使用培养基葡萄糖38.08 g/L,酵母浸粉8.54g/L,KH2PO4:MgSO4=1:1,初始pH值为5,装液量6L/10L,在温度30℃,搅拌速度380r/min,10％接种量的培养条件下,培养132h时达到大值15.8g/L.     

耐高糖面包酵母发酵工艺优化

为了优化耐高糖酵母发酵工艺,基于培养温度、摇床转速、装液量、初始p H、菌体接种量五个因素的单因素实验的结果,之后对装液量、初始p H、菌体接种量进行响应面优化实验。结果表明,最佳工艺条件为:培养温度30℃,摇床转速200 r/min,装液量8.4%,p H4.7,接种量7.4%,在此条件下,酵母细胞干重提高了55.72%。同时,利用5.0 L机械搅拌罐以溶氧反馈流加、恒速流加、间歇流加三种糖蜜补充方式进行酵母细胞培养,绘制生长曲线,发现以溶氧反馈流加方式补充糖蜜更有利于酵母繁殖,最大酵母湿重达到143.95 g/L,达到了耐高糖面包酵母高密度发酵的实验水平,确定了酵母最佳的流加补料方式。     

产辅酶Q10海洋酵母的筛选及培养条件的优化

从50株海洋酵母中选取11株辅酶Q10产量相对高的菌株,经过复筛得到辅酶Q10高产菌株FH-08,经过对氮源、碳源、初始pH值、培养温度等条件的研究分析,得到最佳的发酵条件。通过优化实验,确定培养基的碳源为葡萄糖3%,氮源为酵母粉2%;pH6.5、温度30℃、接种量4%,300ml三角瓶中的装液量为50ml,摇床转速为200r/min。按此条件进行培养,发酵液中菌体生长量为2.34g/200ml,辅酶Q10的产量为28.6mg/L。     

响应面法优化桑黄菌产胞外多糖的培养条件研究

利用响应面分析法对桑黄菌产胞外多糖的液体发酵培养条件进行了优化.研究温度、摇床转速、装液量、接种量、时间等因素对桑黄菌胞外多糖产量的影响.在单因素实验的基础上,利用Box-Benhnken设计和响应面分析法对温度、摇床转速、装液量、接种量进行分析.结果表明,桑黄菌产胞外多糖的最佳液体发酵培养条件为:温度为26.3℃,摇床转速为162r/min,装液量为81.4mL(250mL三角瓶),接种量为16.0%.在此条件下的验证试验表明,胞外多糖平均可达1.866g/L.     

发酵型灵芝醋饮料的工艺研究

以灵芝子实体为原料,通过浸提、酒精发酵和醋酸发酵等步骤,对灵芝醋发酵工艺条件进行了初步探索,研究表明灵芝子实体的最佳浸提条件为0．1MPa、1．0h、料液比1:20、浸提两次,提取液多糖含量为1．25mg/ml;酒精发酵选择接种量10%、时间72～80h、温度30℃较为适宜;醋酸发酵选择接种量10%、温度34～36℃、摇床转速150r/min、起始pH5．5、时间72h较为适宜,发酵原液添加6．5%白砂糖或0．3%蛋白糖可得到酸甜可口、风味独特的灵芝醋酸饮料。     

巴斯德芽孢杆菌培养基及培养条件的优化

通过单因素和正交实验对巴斯德芽孢杆菌(Bacillus pasteurii)培养基组分及培养条件进行研究。结果表明,最适培养基配方(g/L)为甘露醇40、大豆蛋白胨25、氯化铵3、氯化钠10,pH为8.0;最适培养条件为温度30℃,摇床转速200r/min,接种量4.0%(V/V),装瓶量75mL/250mL;在优化条件下,菌体培养24h达到生长高峰期,活菌数达9.52×109cfu·mL-1,分别是普通LB培养基和牛肉膏蛋白胨培养基的1.71、1.55倍。     

灰树花真菌发酵条件优化研究

通过单因素试验及L9(34)正交试验,研究灰树花液体发酵培养过程中接种量、转速、装液量对灰树花真菌菌体及多糖产量的影响.结果表明,三者均有不同程度的影响.接种量的影响显著,适宜于灰树花真菌发酵培养的条件为:接种量10%,摇瓶转速200 r/min,装液量100 mL.     

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.     

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.     

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.     

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.