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1.
多孔淀粉是生淀粉酶在低于淀粉糊化温度下水解各种淀粉形成的一种中空的变性淀粉。作为一种高效、无毒、安全的新型有机吸附剂被广泛用于食品、医药、农业、化妆品、造纸等行业。超声波微波协同组合条件下改进传统酶水解法来制备玉米多孔淀粉。超声波微波协同组合条件下改进传统酶水解法来制备玉米多孔淀粉。采用单因素和L18(37)正交实验,考察温度、时间、超声波功率等对吸油率的影响。结果表明:时间45min,微波功率150W,超声波功率400W,温度56℃,α-淀粉酶加酶量为8U/g,糖化酶与α-淀粉酶配比为6∶1,柠檬酸缓冲液pH为5.4,此时吸油率最高。通过SEM观察,发现多孔淀粉呈蜂窝状,表面孔的数目较多,孔密度均一,孔径不大但孔深适中,同时比表面积增大,颗粒较完整。  相似文献   

2.
多孔淀粉是利用具生淀粉酶活力的酶在低于淀粉糊化温度下水解生淀粉所形成一种新型变性淀粉,可用为微胶囊芯材、及脂肪替代物和吸附剂等。该文综述近年来多孔淀粉制备方法及其在食品微胶囊中一些应用。  相似文献   

3.
酶复合处理制备多孔淀粉的研究   总被引:4,自引:0,他引:4  
多孔淀粉是一种酶处理变性淀粉,是指由具有生淀粉酶活力的酶在低于淀粉糊化温度下作用生淀粉颗粒后形成的多孔性淀粉载体。实验根据生淀粉酶的水解作用机理,并结合扫描电子显微镜观察,从而确定酶复合处理制备多孔淀粉的最佳工艺条件和参数。  相似文献   

4.
微孔淀粉研究进展   总被引:23,自引:1,他引:22  
微孔淀粉是应用具有生淀粉酶活力的酶在低于淀粉糊化温度下水解生淀粉形成一种新型变性淀粉。微孔淀粉经交联、表面活性处理后,能改善其机械性能和表面性质。目前微孔淀粉主要用作微胶囊芯材、吸附剂和脂肪替代物等。  相似文献   

5.
酶法制备多孔玉米淀粉的影响因素研究   总被引:6,自引:1,他引:5  
多孔淀粉是生淀粉酶在低于淀粉糊化温度下水解各种淀粉形成的一种中空的变性淀粉。作为一种高效、无毒、安全的新型有机吸附剂被广泛用于食品、医药、农业、化妆品、造纸等行业。本文以玉米淀粉为原料,采用酶水解法来制备多孔淀粉。以吸水率、吸油率为指标来评价酶的来源、淀粉的预处理条件、酶解条件等因素对多孔淀粉形成的影响。研究结果表明,选择玉米淀粉颗粒的粒度为100目,经过湿热处理后采用复合酶(α-淀粉酶与糖化酶配比为1:3)来制备多孔淀粉。通过正交试验确定酶解最佳工艺条件:酶用量 2.0%,时间20h,温度42℃,pH值4.2,搅拌速率120r·min-1,Ca2+浓度0.15%。  相似文献   

6.
以蜡质大米淀粉为原料,经过β-淀粉酶处理得到不同水解程度的糊精,并对其理化性质进行了研究。研究表明,在实验设定的条件下,控制β-淀粉酶用量为65 U/g不变,处理时间为20 h时淀粉水解率达到最大为56.7%;扫描电镜测试显示,蜡质大米淀粉为多角形的小颗粒,经糊化-酶解后的样品颗粒形貌被破坏,随着水解程度的增加,碎片数量越多;经过β-淀粉酶的水解,淀粉-碘吸附曲线的最高吸收峰位置偏移,样品与碘的吸附能力均低于原淀粉,且随着水解程度增加吸附能力下降;随着水解程度的增加糊精的大分子部分逐渐减少,小分子部分增加;在同一温度下酶解后淀粉样品的溶解度高于原淀粉,膨胀度则相反,随着水解程度和温度的增加溶解度和膨胀度呈增加趋势;酶解后淀粉样品的透明度明显高于原淀粉,但随水解程度的增加透明度下降。  相似文献   

7.
微孔淀粉的制备性质及应用   总被引:9,自引:1,他引:8  
微孔淀粉是用具有生淀粉酶活力的酶在低于淀粉糊化温度下水解生淀粉形成的一种新型变性淀粉。微孔淀粉经交联、表面活性处理后,能改善其机械性能和表面性质。目前微孔淀粉主要用作微胶囊芯材、吸附剂和脂肪替代物等。  相似文献   

8.
多孔淀粉研究Ⅱ淀粉开孔后的物性变化   总被引:2,自引:1,他引:1  
本文详细研究了玉米和籼米淀粉在形成多孔结构后的物性变化,发现淀粉开孔后,除了吸油率提高,堆积密度下降以外;平均粒径降低;比表面积增大;糊化性能基本与原淀粉一致,糊化温度、吸热焓没有明显变化,但糊化温度范围变窄;多孔淀粉基本仍保持原淀粉的结晶形态,但结晶度下降;另外,直链淀粉含量下降。这些特性数据的获得将有助于有效应用多孔淀粉。  相似文献   

9.
以蜡质玉米淀粉为原料,采用脉冲电场(PEF)协同酶解制备多孔淀粉,探究其对多孔淀粉制备效率及吸油率的影响。结果表明:通过PEF改性后,淀粉水解率达到24.28%时所需的酶解时间缩短一半;在相同加酶量的条件下,通过PEF改性后,淀粉水解率为23.11%,较原淀粉显著提高,表明通过PEF改性可降低加酶量;在酶解6 h和加酶量为0.8×10~(-2) mL/g淀粉干基的条件下,经PEF改性协同酶解制备的多孔淀粉水解率为23.11%、吸油率为145.11%、比表面积为1.25 m~2/g,总孔容为4.31 cm~2/g×10~(-3),原淀粉酶解制备的多孔淀粉上述指标分别为18.38%、119.47%、1.16 m~2/g,4.15 cm~2/g×10~(-3),表明通过PEF改性提高酶解淀粉的水解率、吸油率、比表面积和总孔容。扫描电镜结果显示,PEF改性可使淀粉表面产生凹槽状结构;激光共聚焦显微镜观察显示,PEF改性提高了淀粉颗粒对淀粉酶的敏感性;热力学性质测试结果显示,PEF改性多孔淀粉的焓值低于原淀粉,表明PEF改性破坏了淀粉颗粒内部分致密的结晶区。本项研究揭示了PEF改性对淀粉颗粒及其酶解制备多孔淀粉的构效关系,为高效制备多孔淀粉提供了一个新思路,并拓展了PEF可应用的领域。  相似文献   

10.
对酸法水解玉米淀粉制备多孔淀粉进行了研究,同时采用扫描电子显微镜(SEM)和差式量热扫描仪(DSC)对所制备的多孔淀粉的颗粒结构、热学特性、成孔过程等进行分析,并将其与原玉米淀粉进行比较.其最佳工艺条件为:盐酸为10%、温度为40℃、反应时间为12 h、底物浓度为34%.用最佳工艺制备的玉米多孔淀粉,其比容积、溶解度、膨胀率、透明度和吸附能力较原玉米淀粉都有所提高,特别是吸油率增加显著.扫描电子显微镜(SEM)显示多孔淀粉表面布有凹坑或孔洞,类似蜂窝状结构,其孔径不等,密度不均;与原淀粉比较,差式量热扫描仪(DSC)表明其糊化温度范围变窄,焓变无明显变化,结晶大小均一.  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.
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.  相似文献   

13.
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   

14.
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   

15.
Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH3CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH2PO4-20.6 mM Na2B4O7 buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.  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.
An investigation is described in which various polyfunctional compounds were applied to wool in attempts to stabilize the temporary improvements in wrinkle-recovery brought about by ‘annealing’. Several reactive systems involving formaldehyde were found to produce the desired permanently improved wrinkle-recovery.  相似文献   

19.
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   

20.
《造纸信息》2014,(8):79-79
Ministr y of Industr y and Information Technology confirmed that the main expected targets for energysaving and comprehensive utilization in 2014 are:energy consumption and CO2 emissions per unit of industrial added-value decreases by 4.5%,water consumption per ten thousand Yuan of industrial added-value decreases by7%,comprehensive utilization of industrial solid waste is further improved,and pollution emissions in key industries is markedly reduced.  相似文献   

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