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1.
米糠半纤维素提取工艺参数的研究(Ⅰ)   总被引:1,自引:1,他引:1  
以工业脱脂米糖为原料提取米糠水溶性半纤维素及碱溶性半纤维素,是米糠综合利用的又一有效途径。提出了适合于工业化生产的分步提取途径。研究结果表明:水溶性半纤维素的最佳提取工艺参数为:料液比为1:10,3h,60℃;碱溶性半纤维提取工艺参数为:料液比为1:10,4h,25℃,碱液浓度为1.0N。在上述工艺条件下,水溶性半纤维素和碱溶性半纤维素的提取率分别为1.43%和9.02%《  相似文献   

2.
蒸煮对金枪鱼肉及其蛋白质热变性的影响   总被引:2,自引:0,他引:2  
试验测定了金枪鱼肉在蒸气加热过程中的传热曲线以及重量、水分含量和蛋白质组分随中心温度的变化情况.结果显示:中心温度随着加热时间的延长而不断上升,加热初期的升温速度较后期快;蒸煮损失随着中心温度的升高而不断增大,80 ℃时的失重率和失水率分别为19.86%和14.43%;蛋白质组分在加热过程中发生了明显变化,随着中心温度的上升,水溶性蛋白和盐溶性蛋白的含量急剧减少,碱溶性蛋白的含量不断增加,此外,碱不溶性蛋白在60 ℃时开始迅速减少,非蛋白氮的含量随着中心温度的上升也有少量增加.  相似文献   

3.
米糠和麦麸膳食纤维的制备研究   总被引:11,自引:0,他引:11  
探讨了米糠半纤维素和麦麸膳食纤维的提取工艺。结果表明 :( 1 )料液比 1∶1 0 ,6 0℃浸提 3h ,米糠水溶性半纤维素提取率 1 38% ;( 2 )料液比 1∶1 0 ,0 5mol/L的NaOH 2 5℃浸提 3h ,米糠碱溶性半纤维素提取率 8 86 % ;( 3) 0 6 %的NaOH ,α 淀粉酶加入量 0 4% ,70℃浸提 1 5h ,麦麸膳食纤维提取率达 6 6 2 7%。  相似文献   

4.
本文利用碱性过氧化处理,分离提取菠萝皮渣中纤维素和半纤维素组分,得到4个不同纤维素组分(C0、C1、C2、C3)和4个半纤维素组分(H1、H2、H3、H4)。利用红外光谱、离子色谱、热重分析、差示扫描量热分析对这些组分的结构进行表征。结果表明:纤维素提取过程中,碱性过氧化处理能有效去除原料纤维中的半纤维素和木质素,离子色谱分析显示纤维素C3组分的葡萄糖含量达93%以上,较C0、C1、C2有大幅度提升,纯度显著提高;热稳性分析表明纤维素C3在335.8℃左右热解速率达到最大,在128.8℃处有一个的熔融放热峰。不同浓度碱液分步抽提半纤维样品总得率为15.61%,且4个半纤维素样品结构相似;离子色谱分析表明菠萝皮渣中的半纤维素由木糖、阿拉伯糖、半乳糖和葡萄糖组成;热稳定性分析表明半纤维H3在285.2℃时热解速率达到最大,在124.5℃处出现很强的熔融放热峰。  相似文献   

5.
为研究不同涂布率再造烟叶的热解特性,采用热分析技术并结合Coats-Redfern法研究了不同涂布率再造烟叶的热解行为及主要失重阶段的动力学参数变化规律,进一步监测了再造烟叶热解过程中的气体成分释放。结果表明:① 随再造烟叶涂布率增加,样品中C质量分数逐渐升高,O质量分数呈降低趋势,微观组织结构差异不明显。② 再造烟叶的热失重过程可分为干燥脱水(阶段Ⅰ)、低沸点挥发分析出(阶段Ⅱ)、半纤维素分解(阶段Ⅲ)、纤维素及木质素分解(阶段Ⅳ)、炭化(阶段Ⅴ)5个阶段。涂布率由35%增加到50%时,挥发分起始析出温度Ti由220.2 ℃逐渐降低至196.0 ℃,终止析出温度呈升高趋势,阶段Ⅲ和阶段Ⅳ的最大失重速率呈减小趋势,综合热解指数ICP逐渐降低。③ 热解动力学分析显示,阶段Ⅳ的反应活化能E及指前因子A均显著高于阶段Ⅲ的;相同升温速率下,随涂布率增加阶段Ⅲ的活化能从133.08 kJ/mol 升高至160.10 kJ/mol,阶段Ⅳ热解阶段的活化能变化幅度较小。另外,阶段Ⅲ的ΔH随涂布率增加逐渐升高,涂布物提高了该阶段热解所需的能量。④ 在线红外分析表明热解过程中的气体释放主要是小分子气体(如H2O、CH4、CO2、CO等)和轻质焦油组分(如醛酮酸和酚类等),其中CO2气体释放量显著高于其他成分,其次是CO代表的醛酮酸类成分、CC代表的芳香烃类及水分等。  相似文献   

6.
为了研究蒸煮过程中温度对白鲢鱼品质的影响,在常压蒸汽加热下分别测定了温度(20、30、40、50、60、70、80、90℃)对白鲢鱼肉挥发性化合物、蛋白质组分、ATP酶(Ca2+-ATPase)活性、总巯基和活性巯基含量、表面疏水性、失重率、剪切力和p H的影响。结果表明:在60℃时挥发性化合物种类最多为29种,70℃时最少为15种;醇类和烃类物质的含量分别在90和80℃时最高,醛酮类在70℃时最高;水溶性、盐溶性和碱不溶性蛋白、总巯和ATP酶活性随温度的升高而显著(p0.05)下降。碱溶性蛋白、失重率和p H则随温度的升高而显著(p0.05)增加。活性巯基和表面疏水性则随温度的增加而先升高后下降,分别在50℃和60℃时达到最大值0.18 mol/g和410.08 So ANS。剪切力在加热初期(20~30℃)显著(p0.05)降低,到60℃时达到最低值114.39 g。研究结果为白鲢鱼热加工品质控制提供参考。  相似文献   

7.
利用热重分析仪在不同升温速率(10、20、30℃/min)和一定氮气(20 mL/min)条件下对小桐子油生物柴油的热解特性及动力学特性进行了研究。结果表明:小桐子油生物柴油热解过程主要分为低沸点组分挥发,各种脂肪酸甲酯的快速挥发和热解以及残留物缓慢分解失重三个阶段;升温速率增加使各个阶段的起始和终止温度均向高温区轻微移动,使热解失重率略微降低。动力学分析表明:小桐子油生物柴油的热解反应可用三个0.5级反应来描述,根据模型计算的活化能为10.10~85.73 kJ/mol,频率因子为1.82×10-3~1.45×108 min-1。  相似文献   

8.
《食品与发酵工业》2013,(9):205-209
以猕猴桃籽粕为研究对象,根据溶解性的不同,从中分离出了水溶性蛋白、盐溶性蛋白、醇溶性蛋白及碱溶性蛋白,并对各蛋白组分抗氧化活性进行了研究。结果表明:猕猴桃籽中主要蛋白为水溶性蛋白和碱溶性蛋白,分别占其总蛋白质的32.06%和32.26%,其次是醇溶性蛋白和盐溶性蛋白,分别占总蛋白质的1.45%和1.04%。4种不同溶解性的猕猴桃籽蛋白均具有一定的体外抗氧化作用,各蛋白质组分的总抗氧化能力呈现较好的量效关系:4种蛋白抗氧化活性由强到弱的顺序依次为醇溶性蛋白﹥水溶蛋白、盐溶性蛋白﹥碱溶性蛋白;在0.021 mg/mL范围内,除醇溶蛋白外,其余3种蛋白对DPPH自由基的清除能力均呈现良好的量效关系,且水溶性蛋白﹥盐溶性蛋白﹥碱溶性蛋白。因此,猕猴桃籽蛋白质可作为一种潜在的天然抗氧剂进行深入研究。  相似文献   

9.
陈力  匡奕山  张希  李军 《中国造纸》2022,41(7):11-18
本研究采用对甲基苯磺酸(p-TsOH)预处理玉米秸秆,研究了3个预处理因素(p-TsOH质量分数、水解温度和水解时间)对其三大组分分离的影响。通过两相模型,得到木质素和半纤维素脱除动力学模型,并探究了处理后残渣的酶解性能。结果表明,p-TsOH预处理玉米秸秆在温和条件下即可快速溶出木质素和半纤维素,而对纤维素的降解较小;木质素脱除反应和半纤维素脱除反应的表观活化能分别为66.5 kJ/mol和50.5 kJ/mol;预处理后,木质纤维的顽抗结构被破坏,表面木质素含量降低,p-TsOH预处理可以有效提高原料的酶解得率;在p-TsOH质量分数为50%、水解温度为95℃和水解时间为40 min条件预处理后,残渣酶解得率为72.9%。  相似文献   

10.
通过超声辅助Osborne分级法对新型蛋白质源乙醇梭菌蛋白进行分级提取,得到水溶性蛋白、盐溶性蛋白、醇溶性蛋白和碱溶性蛋白4种蛋白质,蛋白含量的大小顺序为碱溶性蛋白>水溶性蛋白>盐溶性蛋白>醇溶性蛋白,对其中含量最多的碱溶性蛋白的提取条件进行优化,结果表明,碱溶性蛋白的最佳提取条件为提取温度50℃、料液比1∶35(g/mL)、提取时间30 min、NaOH溶液质量分数0.3%。此条件下蛋白得率为75.75%。  相似文献   

11.
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.  相似文献   

12.
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.  相似文献   

13.
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.  相似文献   

14.
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.  相似文献   

15.
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.  相似文献   

16.
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.  相似文献   

17.
18.
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.  相似文献   

19.
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.  相似文献   

20.
《印刷工业》2014,(6):95-95
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.  相似文献   

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