比色法快速测定糙米中γ-氨基丁酸含量研究

基于Berthelot显色反应，研究了快速测定糙米中γ-氨基丁酸含量的比色法。结果表明，糙米或发芽糙米粉以60％乙醇溶液为溶剂，在70℃温度下回流提取2h，其离心上清液以重蒸苯酚和次氯酸钠溶液作为显色剂显色反应，在645nm处比色测定，以标准品为对照可以计算样品中γ-氨基丁酸含量。该方法简单、快速、经济，相对标准偏差（RSD）为0．98％，平均回收率为99．4％，适合于大量稻米品种中γ-氨基丁酸的定量分析。     

非浸泡法发芽条件对发芽糙米中γ-氨基丁酸含量的影响规律研究

为了提高发芽糙米中γ-氨基丁酸(GABA)含量,研究采用了一种不同于传统浸泡法的非浸泡法生产发芽糙米.在非浸泡法工艺的基础上,研究了后期发芽条件对发芽糙米中GABA的影响规律,并将浸泡法与非浸泡法进行对比试验.研究结果表明:非浸泡法中发芽温度和发芽时间对发芽糙米中GABA含量的影响规律均为先增加、后降低;利用Excel...     

食品中三种γ-氨基丁酸检测方法比较

应用高效液相色谱(HPLC)、改良纸层析法和Berthelot 色法对不同来源介质中的γ-氨基丁酸(GABA)检测效果进行了比较研究,分别建立了3种方法的GABA检测体系.结果表明,HPLC测定结果准确,灵敏度高,适用范围广;改良纸层析法和Berthelot色法操作简单快速,可用于大量样品中GABA的检测.进一步地,改良纸层析法可用于微生物发酵液等色素含量较少介质中的GABA检测,而比色法更适合成分相时单一介质中的GABA检测.     

温度和时间对发芽糙米中γ-氨基丁酸含量的影响

以福建省农科院水稻所提供的籼稻"繁71-49"为原料,对发芽糙米的生产工艺进行研究.研究了浸泡温度、浸泡时间、发芽温度和发芽时间等因素对吸水率、发芽率和γ-氨基丁酸含量的影响.结果表明,吸水率和发芽率与浸泡温度和时间有关,吸水率影响发芽率,发芽时间对发芽糙米的γ-氨基丁酸含量产生影响;制备高含量γ-氨基丁酸的最适宜条件是:浸泡温度30℃、浸泡时间24 h、发芽温度30℃、发芽时间28 h;采用该工艺,发芽后糙米中γ-氨基丁酸含量是未发芽糙米的2.3倍,是精白米的7.6倍.     

基于Berthelot比色法快速测定糙米中γ-氨基丁酸含量的体系优化

目的与方法：Berthelot比色法是目前测定植物组织中γ-氨基丁酸(GABA)含量的最广泛和最常用方法，但测定结果常常受组织特异性、提取方法和显色条件等的影响。为能准确快速地测定糙米中的GABA含量，本研究基于实验室已优化的Berthelot比色法测定植物叶片中GABA含量的技术体系，以蒸馏水为提取剂，从提取料液比、提取温度、提取时间、显色水浴温度和时间对其进行了系统优化。结果：采用Berthelot比色法测定糙米中GABA含量的最佳提取方法为料液比1 g:20 mL、水浴温度60℃和水浴时间30 min,最适显色反应条件为显色水浴温度60℃和显色时间10 min。结论：优化后的测定体系将尽可能地实现糙米中GABA的充分提取和快速测定，是一个准确可靠、快速经济和科学高效的测定体系。     

发芽糙米新工艺及开发价值研究

采用非浸泡法生产工艺制备发芽糙米,测定其营养指标,结果发现:可以提高发芽糙米中γ-氨基丁酸含量,且可有效抑制发芽糙米水溶性物质的流失和裂纹的产生。减少生产过程中水的使用量和污水的排放量,减少发芽糙米的含水量,降低干燥能耗,有效避免干燥过程中发芽糙米自身的剥离现象。     

响应面法优化富硒富γ-氨基丁酸发芽糙米饼干配方

以富硒富γ-氨基丁酸发芽糙米为原料研制饼干。通过单因素试验探讨了富硒富γ-氨基丁酸发芽糙米、白砂糖、黄油添加量对饼干感官品质的影响,采用Design-Expert中的响应面法对配方进行优化。结果表明,以小麦粉和发芽糙米粉组成的混合粉质量为100%计,富硒富γ-氨基丁酸发芽糙米添加量为57%、白砂糖为26%、黄油为40%时,饼干的感官品质最好,其理化指标符合GB/T 20980—2007要求;饼干中的硒含量为0.38 mg/（100 g）,γ-氨基丁酸含量为23.40 mg/（100 g）。三因素对饼干感官品质影响的大小顺序为：发芽糙米、白砂糖、黄油。     

工艺条件对发芽糙米中γ-氨基丁酸含量的影响

为获得高含量γ-氨基丁酸生产工艺条件,探讨了浸泡时间、培养时间、发芽温度对糙米发芽中γ-氨基丁酸含量的影响应用响应面分析法优化糙米发芽工艺条件,实验结果表明,高含量γ-氨基丁酸生产的最佳条件是:浸泡时间9.3h,发芽时间14.3h,发芽温度27℃,此条件下γ-氨基丁酸含量为232.8mg/100g.     

发芽糙米中γ-氨基丁酸的富集与测定

糙米是一颗完整、有生命活力的种子.发芽可以改变糙米的化学成分.与糙米相比,发芽糙米中的必需氨基酸及生理活性物质种类更多、含量更高,其中γ-氨基丁酸提高率最大.γ-氨基丁酸是一种天然存在的功能性氨基酸,是由谷氨酸经谷氨酸脱羧酶作用生成.概述了γ-氨基丁酸的生理功能及其在糙米中的富集与测定方法,并对糙米发芽条件的优化进行了...     

响应面法优化发芽糙米生物活性物质提取工艺

目的 优化发芽糙米的工艺条件,提高糙米中生物活性物质的含量.方法 利用响应面法优化糙米发芽过程中的温度、时间和湿度,以最大程度地提高γ-氨基丁酸(γ-aminobutyric acid,GABA)、总酚化合物(total phenolic compound,TPC)和谷胱甘肽(glutathione,GSH)的含量.结...     

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.     

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.     

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.     

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.     

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.