三氯氧磷提高谷朊粉的黏性研究

研究了磷酸化处理对谷朊粉黏性的影响。结果表明,磷酸化处理明显改善了谷朊粉的黏性,通过单因素及正交实验,得到磷酸化处理提高谷朊粉黏性的最佳条件为:谷朊粉浓度7.5%、pH6.0、三氯氧磷体积0.5mL,此条件下谷朊粉的黏度为2.88mPa·s;诸因素对改善黏性的重要性依次为:谷朊粉浓度>三氯氧磷体积>pH,通过方差分析显示谷朊粉浓度和三氯氧磷体积对黏性的影响最为显著。     

改性谷朊粉的制备及其凝胶结构分析

先将谷朊粉进行脱脂处理,然后采用微波、三氯氧磷和转谷氨酰胺酶法对谷朊粉进行修饰,并使用电子显微镜扫描分析了不同干燥工艺制备的改性谷朊粉凝胶结构.结果表明:脂肪对改性谷朊粉的凝胶性能影响较小,改性谷朊粉的凝胶临界浓度为16%,冷冻干燥比常压干燥更能明显地保持改性谷朊粉的交联结构.因此,酶法改性结合冷冻干燥是一种制备具有优良凝胶性能改性谷朊粉的先进工艺.     

微波处理改善谷朊粉粘性研究

探讨了微波处理对谷朊粉粘性的影响。结果表明:微波处理明显地改善了谷朊粉的粘性,通过单因素及正交实验,得到微波处理提高谷朊粉粘性的最佳条件为:谷朊粉浓度为0.1g/ml、pH值为4、加热时间为120s和微波功率为630W,此条件下的粘性为9.20mPa·s;诸因素对改善粘性的重要性依次为:pH值、谷朊粉浓度、微波处理时间、微波功率,通过方差分析显示谷朊粉浓度和pH值对粘性的影响最为显著。     

两种物理方法改善谷朊粉乳化性效果的研究

分别用微波法和湿热法两种物理方法处理谷朊粉,比较不同处理组的乳化活性和乳化稳定性,确定乳化效果较好的物理方法.结果表明,经两种物理方法处理的谷朊粉乳化性比原始谷朊粉都得到极大提高,微波法比湿热法处理的谷朊粉乳化效果好;除pH值变化曲线相似外,微波处理所用谷朊粉浓度比湿热处理少1%,反应时间约是湿热处理的1/6,温度比湿热处理低15℃;微波法处理谷朊粉的溶解度比湿热法高28.7%.从SDS-PAGE图谱分析两种物理方法处理谷朊粉的结构变化相似.     

谷朊粉的有限酶解对其分散性及胶黏性的影响

为了改善谷朊粉在水溶液中的物化性能,利用碱性蛋白酶对谷朊粉进行了有限水解。通过单因素实验,分析了底物浓度、反应温度、加酶量和反应时间对其分散稳定性、胶黏性的影响,并分析了酶解物中的蛋白质分子粒径。通过正交实验确定了以提高谷朊粉分散特性和胶黏性为目的的最佳酶解条件为:底物浓度0.30g/mL、温度50℃、加酶量0.50%、反应时间20min,此时可使谷朊粉的相对分散稳定性达到96.3%,黏度为3.2mPa.s,蛋白质平均分子粒径604.6nm。分析显示,不同酶解样品分散稳定性、黏度和蛋白质平均分子粒径三种指标之间的变化趋势并不完全一致。     

微波处理提高谷朊粉乳化性的研究

以谷朊粉为原料，研究了利用微波处理对谷朊粉乳化性的改善作用，通过pH值，谷朊酚浓度，微波能量及加热时间对谷朊粉乳化性的影响，确立了四因素三水平的正交实验，探讨了微波处理提高谷朊酚乳化性的最佳条件。结果表明：各因素对提高谷朊粉乳化性的明显程度依次为：加热时间＞pH值＞谷朊粉浓度＞微技能量。正交试验分析表明，微波处理提高乳化性的最佳作用条件为：pH值＝10．0、谷朊粉浓度＝9．0％、加热时间=100和微波能量＝560W。在最佳条件下，谷朊粉的乳化活性及乳稳定性均为100％，溶解度＝37．6％。说明微波处理显著提高了谷朊粉的乳化性。     

果胶-谷朊粉复合物对谷朊粉分散稳定性的影响

采用吸光度法检测谷朊粉的分散稳定性,研究并优化了果胶-谷朊粉复合物的制备工艺参数。通过单因素和正交实验,以分散稳定性为指标,探索果胶-谷朊粉复合物制备工艺的最佳条件:料液比为1∶10,谷朊粉:果胶(w/w)为40∶1,pH4.5,温度40℃,反应时间60min。在最佳制备条件下的复合物分散稳定性达到86.89%,10%浓度的分散液粘度仅16mPa·s。     

酶解谷朊粉-卡拉胶复合体系凝胶特性研究

采用物性仪研究了酶解谷朊粉-卡拉胶复合体系的胶凝条件和凝胶特性。结果表明,酶解谷朊粉为300 mg/mL时仍是松软的糊状形态,添加0.3%卡拉胶时凝胶成形较好;随着卡拉胶浓度或酶解谷朊粉浓度增加,凝胶的黏性和弹性持续提高,而硬度则在0.3%卡拉胶或250 mg/mL谷朊粉时达到最高点后逐渐下降;随着加热温度增加或加热时间延长,凝胶的质构特性均呈现先逐渐增加后又下降的趋势。综合分析可知,在酶解谷朊粉300 mg/mL、卡拉胶0.3%8、0℃加热30 min条件下形成的复合凝胶硬度(252.822 g)、黏性(128.112 g.s)和弹性(0.045)均达到了较高值。     

超声波处理提高谷朊粉溶解度的工艺条件

以谷朊粉为原料,研究了利用超声波处理对谷朊粉溶解度的改善作用,通过pH值、离子强度、脉冲振幅、超声时间、脉冲on值和off值对谷朊粉溶解度的影响,确立了四因素三水平的正交试验,探讨了超声波处理提高谷朊粉溶解度的最佳条件。结果表明：各因素对提高谷朊粉溶解度的明显程度依次为脉冲振幅＞脉冲on值和off值＞超声时间＞pH值。正交试验分析表明,超声波处理提高溶解度的最佳作用条件为pH4.5、脉冲振幅60%、超声时间为120s、脉冲on值和off值分别为40s和20s。在最佳条件下,谷朊粉的溶解度为51.12mg/ml,与未处理时相比,溶解性提高到18.4倍,拓宽了谷朊粉的应用范围。     

微波处理对酶解谷朊粉的影响

以谷朊粉为原料,研究了微波预处理对中性蛋白酶水解谷朊粉水解度的影响。结果表明,微波作用不改变酶解反应的最适温度和pH,也不改变水解度与水解温度、pH、底物浓度、酶浓度之间关系曲线的变化趋势,但使谷朊粉酶解后的水解度提高了。在微波功率540W,作用时间120s的预处理后,中性蛋白酶水解谷朊粉的最佳工艺条件为:酶加量3%E/S,反应温度40℃,pH 8.0,底物量8%,水解时间2h,水解度为31.58%。     

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.     

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.     

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.     

Analysis on Economic Indicators from 62 Enterprises in Printing Machinery Industry in Q1 2014

Operation of printing machine industry was still unsatisfactory in the first quarter of 2014.Analysis on operation of printing machine industry.a.Market demand was not strong;sales of product undulated and declined.According to the statistics,the total industrial output value fell by 19.28% in the first quarter of 2014 than the average quarter value in 2013; industrial added value decreased by 4.16%; sales revenue dropped by 22.83%. h. Business operation of enterprises was in poor condition. c. R＆D of new products is an important transformation guarantee for enterprises. d. To take self explore new ways upgrading advantages,and explore new ways.