香菇水解液的美拉德反应条件研究

以香菇酶解液和葡萄糖为主要底物制备美拉德反应产物。通过单因素和正交实验,考察了微波加热对美拉德反应褐变程度的影响。结果表明:葡萄糖添加量为10%,香菇水解液初始pH值调整为9,加热时间为4min,微波功率为800W时褐变程度最佳。感官评价反应产物具有独特的酱香味。     

葡萄糖-牡蛎酶解液美拉德反应体系的抗氧化活性

以牡蛎酶解液与葡萄糖建立美拉德反应体系,以1,1-二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl, DPPH）自由基清除率、金属离子螯合能力和还原能力为指标,通过葡萄糖质量分数、反应温度、pH值以及反应时 间4 个因素的单因素试验和正交试验优化得到具有强抗氧化活性的美拉德反应产物适宜反应条件。结果表明,葡萄 糖-牡蛎酶解液美拉德反应产物具有较强抗氧化活性的反应条件为葡萄糖质量分数4%、反应温度120 ℃、pH 7.0、 反应时间120 min。在此组合条件下,牡蛎酶解液美拉德反应得到的反应液的DPPH自由基清除率为93.2%,金属离 子螯合能力为22.5%,还原能力为1.436。     

复合酶解及美拉德反应制备鱿鱼调味品

目的以阿根廷鱿鱼为研究对象,采用酶解法结合美拉德反应制备海鲜调味剂。方法以感官评定为主要指标,确定风味蛋白酶、中性蛋白酶、木瓜蛋白酶3种蛋白酶的用量。通过正交试验确定3种酶的最佳质量配比,并将复配酶作为接下来的实验用酶。在单因素试验的基础上进行正交试验优化酶解工艺。美拉德反应以质量配比1:1:1的D-木糖、D-葡萄糖、蔗糖作为实验用糖。通过单因素试验探讨不同pH、反应温度、反应时间和加糖量对美拉德反应产物的感官评定的影响。结果最佳酶解工艺条件为:pH 6.8,酶解温度50℃,底物浓度15%,加酶量0.30%,酶解时间4 h。美拉德反应最佳反应条件为:pH 8.0、反应温度110℃、反应时间60 min、加糖量1.0%。将最佳反应条件下的美拉德反应产物在4500 r/min,20 min条件下离心取上清液后,浓缩为原体积的25%,最后进行冷冻干燥得到浅棕色的具有鱿鱼特征香味的海鲜调味品。结论利用复合酶和美拉德反应制备鱿鱼调味品具有广阔的应用前景,有利于充分发掘鱿鱼的利用价值,拓宽消费者选择空间,丰富调味品市场。     

鳗鱼骨酶解及美拉德反应制备优质风味物工艺研究

利用鳗鱼骨为主要原料进行蛋白酶水解,在酶水解液加入木糖并通过美拉德反应制备出具有鳗鱼风味的提取物产物。实验以感官综合评价为指标,通过单因素试验和正交试验,利用模糊综合评价方法分析并优化工艺配方。结果表明,鳗鱼骨酶解液美拉德反应工艺条件为反应初始pH值7.5、反应时间50 min、反应温度120℃、木糖添加量1.5%时制得的美拉德反应产物的风味得到了较大改善,色泽呈棕褐色或棕黄色,烤鳗鱼滋味和焦香味浓郁,香气突出,没有其他不良异味,该为海洋功能性食品的开发提供了参考。     

美拉德反应用于牡蛎酶解液脱腥的研究

研究了美拉德反应脱除牡蛎酶解液腥味的最佳工艺参数,并分析了美拉德反应产物的游离氨基酸组成.结果表明,美拉德反应的最佳条件为:温度100℃,时间30min,pH7.5,原料配比1:1.最佳工艺条件下的美拉德反应产物中必需氨基酸含量和风味氨基酸含量分别占49.88%和32.62%.经过关拉德反应后,酶解液达到了很好的脱腥效果.     

酶解鲮鱼制备鱼香调味料的研究

利用蛋白酶水解鲮鱼肉得到水解蛋白,然后将水解蛋白与还原糖进行美拉德反应制备肉味香精。实验结果表明:水解鲮鱼肉的最适蛋白酶为复合蛋白酶,最适酶解温度为50℃,最适酶量为0.2%,最适料液比为1∶1,最适pH值为7.0,最适酶解时间为6h;所得的鲮鱼水解液与木糖进行美拉德反应,当最适木糖浓度和温度分别为30%和110℃时,所得产物呈黄色,鱼香味较浓。     

复合酶处理废弃烟末制备烟用美拉德香精

利用α-淀粉酶和β-淀粉酶的复合酶酶解烟草废弃物、浓缩酶解液与特定的氨基酸进行美拉德反应来制备烟用香精。通过单因素实验确定最适酶解条件:质量分数0.2%α-淀粉酶和质量分数3%β-淀粉酶,酶解时间7 h,pH 5.4,温度50℃;在酶解制备的美拉德反应基液中加入氨基酸后,通过正交实验优化美拉德反应条件:反应系含水率15%,反应时间5 h,pH 8,反应温度115℃。经验证实验可知,酶解液中还原糖的质量浓度提高了28.07%,通过GC-MS分析表明,从美拉德反应产物中共检测100种物质,其中与烟草香味有关的化合物有57种,相对质量分数为71.277%。     

海参肠酶解液美拉德反应增香工艺研究

目的优化影响海参肠酶解液美拉德反应的因素,以达到脱腥增香的效果。方法以感官评价,反应后的pH值和美拉德反应产物吸光值为指标,通过优化美拉德反应的条件(还原糖种类和用量、氨基酸种类和用量、反应温度、时间、pH值),获得最佳反应条件。结果最佳条件为:葡萄糖:木糖=1:1,添加量为8%,赖氨酸:精氨酸=2:1,添加量为3%,反应体系的pH=8.5,反应的温度为120℃,反应的时间为32 min。此条件下得到的海参肠美拉德反应产物有明显的焦香味,无腥臭气味。结论本研究提高了海参肠的利用价值,可以进一步开发可食用产品及配料,极大地提高了海肠的利用价值。     

酪蛋白的酶促水解及其水解物的美拉德反应

以酪蛋白为原料，经蛋白酶催化水解，得到蛋白水解液，进而和糖进行美拉德反应制成新型非酶棕色化香料。水解酶为胰蛋白酶和木瓜蛋白酶。本文利用正交试验设计，系统地研究了蛋白酶催化条件下酪蛋白的水解，研究了各实验因素对水解效率的影响。最佳水解条件是：水解温度50℃，pH8．0，水解时间24h，酶-底物浓度比0．5％～1．0％。美拉德反应合成的新型非酶棕色化香料，具有浓郁的烤土豆香味。可应用于食品和烟草的加香。     

鱼蛋白水解液美拉德反应条件优化及反应前后氨基酸组成变化

以蛋白酶水解鳙鱼肉制得的蛋白水解液为对象,进行美拉德反应,获得具有酱香味的美拉德产物.通过单因素及正交试验得到的最佳反应条件是:pH 9.5、反应温度120℃、葡萄糖添加量0.15 g/mL、反应时间100min.硫胺素、维生素C对美拉德反应褐变程度及产物的气味会产生不利的影响.木糖的加入有利于美拉德反应褐变的产生,但高含量的木糖对产物气味有不利的影响.反应前、后氨基酸的分析结果显示,氨基酸变化明显的主要是:精氨酸(减少74.44％)、赖氨酸(减少65.50％)和酪氨酸(减少42.50％),说明这几种氨基酸是参与该美拉德反应产生酱香味的主要氨基酸.     

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.     

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.     

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.