速冻山药热烫工艺研究

对山药的速冻预处理工艺进行了研究。在实验中,以清水为热烫液,通过测定Vc的含量、可溶性固形物的含量、过氧化物酶和多酚氧化酶的活性这四个指标来确定最佳的热烫时间和温度。同时对经热烫和不经热烫两种不同处理的山药在冻藏过程中的色泽变化进行了评价。研究表明,速冻山药必须进行热烫处理以使酶失活。最佳的热烫时间和温度为60s和90±1℃。     

速冻芦笋的热烫工艺条件研究

对速冻芦笋的热烫工艺条件进行了研究。结果显示，热烫因子笋径(A)、热烫温度(B)和热烫时间(C)对芦笋热烫效果影响的主次顺序为A＞B＞C；笋径对多酚氧化酶(PPO)和过氧化物酶(POD)活性有极显著的影响，对芦笋烫后的感官品质有显著影响；热烫温度和时间对POD活性有显著影响。芦笋热烫的适宜条件范围为茎粗0．8—1．4cm，热烫温度88—95℃，热烫时间为2—3min。热烫最佳处理组合为A2B3C1。     

生姜速冻前热烫工艺的实验研究

对速冻籽姜冻结前的热烫工艺进行了研究,分析了漂烫温度、时间对原料过氧化物酶活性、Vc含量及感官品质带来的影响,确定了漂烫工艺的最佳参数。     

阳春长山药热泵干燥工艺初步研究

采用热泵干燥技术对阳春长山药进行干燥试验研究,以热烫处理、切片厚度和干燥温度为试验变量,通过对干燥后山药品质进行分析,确定最佳工艺参数为:新鲜物料切片后直接浸泡清水无需进行热烫处理,切片厚度6 mm,热泵干燥温度60℃,干燥时间3 h~4 h,可获得较好的山药干制品。     

甘蓝复合汁工艺参数的确定

利用脱水蔬菜厂的甘蓝下脚料,经超滤澄清与苹果汁复合,开发出一种甘蓝、苹果复合汁饮料.通过研究不同热烫时间、温度对还原VC和不同酶解条件(酶用量、酶配比、pH值、时间和酶解温度)对出汁率与粘度的影响,采用正交试验确定了最佳酶解工艺为:质量分数0.06％的纤维素酶用量,物料:酶质量比30:1,pH值5.5,酶解时间40 min,温度45℃.     

甜玉米速冻前热烫工艺研究

对甜玉米速冻前热烫工艺进行了研究,通过PPO、POD等酶活性、可溶性糖和Vc等指标的检测分析和感官评价,探讨了水煮热烫处理、蒸气热烫处理和微波热烫处理等热烫处理方式、热烫处理时间等因素对速冻甜玉米品质的影响。试验结果表明,适宜的热烫处理工艺(蒸气热烫20min)能减少可溶性糖和Vc的损失,同时钝化PPO和POD酶活性,提高速冻甜玉米的品质。     

紫山药香菇营养酱的开发研制

以紫山药和香菇为主要原料,开发研制富含功能性成分的营养酱。通过单因素试验和正交试验确定了热烫温度、热烫时间、紫山药块和香菇块大小、大豆酱的加入量、紫山药和香菇质量比的最佳方案。结果表明:以热烫温度90℃、热烫时间60s、紫山药和香菇切块大小0.5×0.5×0.5cm~3、大豆酱加入量20%、紫山药和香菇质量比1∶2为最佳工艺配方。经测定,此工艺配方条件下酱体中含有蛋白质19.5g/100g、脂肪6.8g/100g、多糖1.56g/100g。可知在此条件下能得到高蛋白、低脂肪、保健价值高、口感良好、香味浓郁的紫山药香菇营养酱。     

高压二氧化碳技术速冻香菇工艺

采用高压二氧化碳技术(high pressure carbon dioxide,HPCD)对香菇进行速冻,以期解决国内食用菌速冻技术存在的能耗大、成本高的问题。在原料热烫钝酶的基础上,通过单因素试验和正交试验,并结合速冻产品感官评价对工艺条件进行优化。结果表明:HPCD速冻香菇最佳工艺参数为处理釜初温6℃、处理釜设定压力7MPa、卸压时间4min,且卸压时间为影响速冻产品品质的最显著因素。     

速冻蔬菜热烫处理的优化和节能

大多数速冻蔬菜必须经过热汤处理以保证其在冻藏期间质量的稳定性。但是热烫易引起蔬菜的色、香、味和质地的变化。目前蔬菜的热烫终点以过氧化物酶作为指示剂来确定。有关研究表明，以过氧化物酶的指示剂会导致某些蔬菜热烫过度，因此必须寻找对这蔬菜更合适的酶作为指示剂，以便优化热烫处理。在速冻蔬菜的热烫过程中要消耗大量的能量 和水，有一种热烫－冷却组合器可较好地解决蔬菜热烫过程的节能、节水问题。     

脱水海芦笋的护色工艺研究

研究了不同Na2CO3质量分数、浸泡时间、过氧化酶相对酶活、热烫时间、含盐量对脱水海芦笋护色效果的影响,通过单因素和正交实验,对脱水海芦笋的护色工艺进行了研究.结果表明:海芦笋在质量分数为1%的Na2CO3溶液中按料液质量体积比1 g∶8 mL浸泡15 min取出后,在95～100 ℃沸水浴中热烫7 min,此工艺的护色效果最佳.     

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.