复合凝固剂对豆腐品质的影响

我国传统的豆腐生产工艺中广泛使用的是单一凝固剂。单一凝固剂作用于大豆蛋白制成的豆腐各不相同。本文对凝固剂的种类与豆腐品质的关系进行了研究,试验先以出品率、含水率、保水性、蛋白含量和感官评价确定了3种单一凝固剂（石膏、氯化镁和葡萄糖酸-δ-内酯）的最佳用量,然后将葡萄糖酸-δ-内酯（GDL）、石膏（CaSO4）与氯化镁按一定比例混合制成复合型凝固剂,然后按照优选法的原则,确定了3种凝固剂用量比例为5∶3∶2时,其豆腐出品率、保水性、蛋白质含量、豆腐外观、内部结构及风味等各个方面均好于单一凝固剂制品豆腐。     

豆腐用复合凝固剂的研究

中国传统豆腐广泛应用的是单一凝固剂(石膏或卤水),凝固剂的浓度与用量直接影响豆腐的品质,研究确定了单一凝固剂的浓度,并在此基础上,将石膏与卤水按一定比例混合制成复合型凝固剂,并通过实验优选法获得了最佳配比,当石膏与卤水质量比为4∶6时,豆腐质量和口感都较好。     

加热即食方便豆腐脑产品的开发

采用豆粉冲调、均质、添加凝固剂和85 ℃水浴加热15 min的方式制作即食豆腐脑。研究了不同添加量的葡萄糖酸-δ-内酯（GDL）、氯化钙和氯化镁对制作的即食豆腐脑特性的影响。结果表明,GDL、氯化钙和氯化镁单一使用时,添加量分别在0.50%、0.30%和0.40%时豆腐脑产品凝胶效果较好。在对以上3种凝固剂进行不同比例复配,从质构特性和感官评价两方面确定了GDL、氯化钙、氯化镁的复配比例在10∶2∶3时开发的即食新产品相较于单一使用凝固剂和其他3种复配比例有显著优势（P＜0.05）。     

提高内酯豆腐质量的探讨

用葡萄糖酸-δ-内酯（Gluconil-δ-cfon．G．D．L）作为豆腐的凝固剂,生产的豆腐持水性好,洁白细嫩,味美卫生,保鲜期较长。但内酯豆腐偏软,易破裂,不能用于煎炒,且略有酸味。为了解决这些问题,经反复试验,选出一种混合凝固剂及几种淀粉添加剂,从根本上解决了内酯豆腐存在的不足,现将试验方法和结果报道如下。1试验材料与方法1．1试验材料葡萄糖酸-δ-内酯：上海黄海制药厂蔗糖脂肪酸酯：浙江金华第二制药厂氯化镁、磷酸氢二钾、碳酸钙：化学纯大豆、地瓜粉、面粉、纯米粉：市售1．2凝固剂的种类及用量①葡萄糖酸-δ-内酯70％MgCl222％CaCO35％蔗糖脂肪酸酯3％将上述原料混合,每kg豆浆加     

彩色豆腐加工技术

以胡萝卜和大豆为主要原料,制作出具有营养价值的彩色豆腐.并对豆浆与菜汁的添加比例,凝固剂的选择与用量进行研究,结果表明:豆浆与菜汁的最佳配比为3∶1,凝固剂采用6-葡萄糖酸内酯与氯化钙按7∶3的质量比例混合,添加量为0.3%.     

高纤维猕猴桃营养型保健果冻的研制

以猕猴桃果汁、魔芋精粉为主要原料研制高纤维猕猴桃营养果冻，分别对猕猴桃汁的用量，魔芋精粉的浓度、凝固剂的用量等工艺条件进行了研究，得到了最佳工艺配方：猕猴桃汁7％，魔芋精粉0．35％，凝固剂0．15％、柠檬酸0．25％，糖、香精、色素等各适量。     

复合凝固剂组分对豆腐品质影响的研究

在我国豆腐生产中广泛使用的是单一凝固剂。每种单一凝固剂对豆腐品质的影响不同。本文对凝固剂与豆腐品质的关系进行了研究 ,将石膏与δ 葡萄糖酸内酯按一定比例混合制成复合型凝固剂 ,并通过试验优选法获得了最佳配比。当δ 葡萄糖酸内酯与石膏质量比为 2∶1时 ,其出品率、含水率、离水率、蛋白质含量、豆腐外观、内部结构及风味等各个方面均好于单一凝固剂豆腐。     

酶法制取JA澄清剂的研究

采用纤维素酶和酸性蛋白酶对甲壳质进行酶解改性，并对实验条件进行了比较筛选。确定最适生产工艺条件：底物浓度为1％。纤维素酶用量为25μ／g，酸性蛋白酶用量为50μ／g，pH4．0-4．5．水解温度为45℃，转化时间4-5h，而且双酶水解明显优于单一酶的作用。     

甜玉米风味豆腐脑的研制

本文以大豆、甜玉米为主要原料,利用葡萄糖酸-δ-内酯作为凝固剂,研究了甜玉米风味豆腐脑的制作工艺．并采用正交优化试验方法,研究了豆浆浓度、甜玉米汁与白砂糖的用量比例以及葡萄糖酸-δ-内酯用量对甜玉米风味豆腐脑产品质量的影响。试验结果表明：当打浆时干大豆与水的比例为1：13,甜玉米汁用量为8％,白砂糖用量为7％,β-环状糊精用量为1．5％,葡萄糖酸-δ-内酯用量为0．25％．凝固温度为78℃,凝固时间为20min时,甜玉米风味豆腐脑产品的色泽呈淡黄色,具有良好的甜玉米风味和纯正的豆香味,并且豆腐脑的口感细腻、凝胶强度适中。     

凝固剂及豆腐的品质

豆腐凝固剂对于豆腐的加工生产,对于豆腐产品质量的优劣都起着重要作用。日本豆腐业对于豆腐凝固剂的研究尤为重视。 豆乳→添加凝固剂凝固→入箱压榨→脱水→豆腐,这是日本木棉豆腐的生产流程,它使用的凝固剂为CaSO_4。凝固剂用量为0.3～0.6％之间,加工制作的豆腐的质量差异,见图1～3。从图中可视豆腐的硬度、豆腐的固     

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.     

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.     

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.     

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.     

Influence des ions sur le pouvoir hydratant de l'ure e: e tude sur peau de porc ex vivo

This study deals with the influence of ions (NaCl and MgSO4) in a W/O emulsion containing 10% urea. Moisturization kinetics are assessed by corneometry on pig skin ex vivo. The formula's influence on urea penetration is measured by infrared spectrometry with an ATR device and the stripping method. Corneometry and spectroscopy were chosen to record simultaneously the hydratation levels and urea localization into superficial cell layers. Urea crystallization after evaporation of emulsions and aqueous solutions is described. Results show that urea does not hydrate nor penetrate when applied to the skin through an aqueous gel. In a W/O emulsion, sodium chloride increases the ability of urea to moisturize without improving penetration. In vitro urea crystallization is disturbed by sodium chloride or magnesium sulphate for solutions and emulsions. This stabilization by ions is correlated with good moisturization values. The stabilization of urea in the solute state provided by ions increases its water epidermal binding capacity without enhancing penetration.