This work investigates the physico-chemical and mechanical properties of tannins extracted from wood for composite materials manufacturing. Sustainable knowledge (in terms of physico-chemical properties and behaviours...This work investigates the physico-chemical and mechanical properties of tannins extracted from wood for composite materials manufacturing. Sustainable knowledge (in terms of physico-chemical properties and behaviours) of the material is needed to further enhance its applications. The condensed tannins extracted from the Bark of Ficus platyphylla (BFP) and the Bark of Vitellaria paradoxa (BVP) were analyzed using Matrix Assisted Laser Desorption/Ionization Time-Of-Flight (MALDI-TOF), Mass Spectroscopy and Attenuated Total Reflectance Fourier Transform Mid-InfraRed (ATR-FT MIR) spectra in the ranges 1800 cm-1 and 600 cm-1, as well as using CP MAS 13C-NMR. It was found that, these two tannins are procyanidin/prodelphinidin and made up of catechin/epicatechin, gallocatechin/epigallocatechin units, fisetinidin, galloyl and carbohydrates residues. Furthermore, BFP and BVP tannin bonded particleboard densities lie in the range recommended by NF EN 326-1994 standard. The resins also yielded good internal bond strength results of the panels, above relevant international standard specifications minimum requirements for interior-grade panels. The Transmission Electron Microscopy with Energy Dispersive X-ray Spectroscopy Analysis (TEM/ EDXA) are showing the ultrastructure and reveal that most of the resin material appears to be in an amorphous phase mainly composed of carbon/oxygen with small amounts of K, Ca and Mg. These particles have a very irregular morphology.展开更多
Objective:To investigate the changes in total phenols,flavonoids,tannins,vitamin E, β-carotene and antioxidant activity during soaking of three white sorghum varieties.Methods: The changes in total phenols,total ilav...Objective:To investigate the changes in total phenols,flavonoids,tannins,vitamin E, β-carotene and antioxidant activity during soaking of three white sorghum varieties.Methods: The changes in total phenols,total ilavonoids,tannins,phenolic acids compounds,flavonoid components,vitamin E,P-carotene and antioxidant activity during soaking of sorghum grains were determined.Results:Total phenols,total flavonoids,tannins,vitamin E,P-carotene and antioxidant activity in raw sorghum were ranged from 109.21 to 116.70,45.91 to 54.69,1.39 to 21.79 mg/100 g,1.74 to 5.25,0.54 to 1.19 mg/kg and 21.72%to 27.69%and 25.29%to 31.97%,respectively. The above measured compounds were significantly decreased after soaking.p-Hydroxybenzoic acid,vanillic acid,syringic acid and cinnamic acid represent the major phenolic acids in Dorado variety.While ferulic acid,p-coumaric acid,gallic acid and caffeic acid represent the major phenolic acids in Shandaweel-6.On the other hand,protocatechuic acid represents the major phenolic acids in Giza-15.Regarding flavonoids components,Dorado was the highest variety in kampferol and naringenin while Shandaweel-6 was the highest variety in luteolin, apigenin,hypersoid,quercelin and christen.Finally,Giza-15 was the highest variety in catechin. Phenolic acids,flavonoid compounds and antioxidant activities were decreased after soaking. Conclusions:Sorghum varieties have moderate quantities from total phenols,total flavonoids, tannins,phenolic acids compounds,flavonoid components,vitamin E,P-carotene and antioxidant activity which decreased after soaking.展开更多
The stepwise stability constants of coordination compounds from sulfonatedsheoak tannin with metal ions have been determined by pH potential method with catechol asmodel compounds at 20℃and constant ionic strength.
Extracts of plant origin,particularly tannins,are attracting growing interest for the sustainable development of materials in the industrial sector.The discovery of new tannins is therefore necessary.The aim of this w...Extracts of plant origin,particularly tannins,are attracting growing interest for the sustainable development of materials in the industrial sector.The discovery of new tannins is therefore necessary.The aim of this work was to contribute to the understanding of the properties of Paraberlinia bifoliolata tannin by Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectroscopy MALDI-TOF/MS and Carbon 13 Nuclear Magnetic Resonance(13C NMR).The chemical composition of tannin extracted from Paraberlinia bifoliolata bark was determined,as was the mechanical strength of the resin hardened with Acacia nilotica extracts.Yield by successive water extraction was 35%.MALDI-TOF/MS analysis revealed the presence of three new compounds in this tannin,previously unknown in this family of extracts.These are 3-hydroxyproline acid,N-methyl-4-hydroxypipecolic acid and N-methyl-5-dihydroxypipecolic acid.The identification of the above molecules means that this tannin can be used for industrial applications,as a resin in the manufacture of particleboard and in the formulation of green corrosion inhibitors.This information is reinforced by 13C NMR spectrometry,which indicates the presence of several polyflavonoid units,confirming the condensed nature of the tannin.Thermomechanical analysis of the resin formed by the purified tannin of Paraberlinia bifoliolata to which a vegetal biohardener has been added provided a Modulus of Elasticity(MOE)value of 4840 MPa at 150℃,confirming its possible use as a binder resin in the manufacture of wood panels as well as for the formulation of a corrosion inhibitor.展开更多
Objective:To investigate the antioxidant activity,total phenolic and total tannin content of the pericarp and the seed of Coffea benghalensis(C.benghalensis) and Coffea liberica compared to Coffea arabica(C.arabica).M...Objective:To investigate the antioxidant activity,total phenolic and total tannin content of the pericarp and the seed of Coffea benghalensis(C.benghalensis) and Coffea liberica compared to Coffea arabica(C.arabica).Methods:The antioxidant potential,total tannin and polyphenol contents of the immature and mature seed and pericarp of C.benghalensis and Coffea liberica were quantified and compared to C.arabica.Enhanced chemiluminescence(ECL).2,2-diphenyl-1-picrylhydruzyl(DPPH).oxygen radical absorbance capacity,Folin-Ciocaltcau method and total tannin content assays were used.Results:Trolox equivalent(TE/g plant material) values obtained by ECL and DPPH methods showed loose correlation(r^2=0.587)while those measured by oxygen radical absorbance capacity assay were higher without correlation in each plant.A closer correlation was detected between the ECL method and the percentage antioxidant activity of the DPPH technique(r^2=0.610 7) in each species,however the immature pericarp of C.benghalensis showed much higher DPPH scavenging potential than was seen in the ECL assay.The immature pericarp of C.benghalensis expressed the highest tannin and polyphenol content,and a high polyphenol level was also detected in the immature seed of C.arabica.The immature pericarp of Bengal and Liberian coffees showed the largest amount of phenolic contents.Conclusions:The obtained data highlight the potential role of C.benghalensis as a new source of natural antioxidants and polyphenols compared to C.arabica.展开更多
文摘This work investigates the physico-chemical and mechanical properties of tannins extracted from wood for composite materials manufacturing. Sustainable knowledge (in terms of physico-chemical properties and behaviours) of the material is needed to further enhance its applications. The condensed tannins extracted from the Bark of Ficus platyphylla (BFP) and the Bark of Vitellaria paradoxa (BVP) were analyzed using Matrix Assisted Laser Desorption/Ionization Time-Of-Flight (MALDI-TOF), Mass Spectroscopy and Attenuated Total Reflectance Fourier Transform Mid-InfraRed (ATR-FT MIR) spectra in the ranges 1800 cm-1 and 600 cm-1, as well as using CP MAS 13C-NMR. It was found that, these two tannins are procyanidin/prodelphinidin and made up of catechin/epicatechin, gallocatechin/epigallocatechin units, fisetinidin, galloyl and carbohydrates residues. Furthermore, BFP and BVP tannin bonded particleboard densities lie in the range recommended by NF EN 326-1994 standard. The resins also yielded good internal bond strength results of the panels, above relevant international standard specifications minimum requirements for interior-grade panels. The Transmission Electron Microscopy with Energy Dispersive X-ray Spectroscopy Analysis (TEM/ EDXA) are showing the ultrastructure and reveal that most of the resin material appears to be in an amorphous phase mainly composed of carbon/oxygen with small amounts of K, Ca and Mg. These particles have a very irregular morphology.
基金financially supported by Department of Biochemistry,Faculty of Agriculture.Cario University,and Food Technology Research Institute(FTRI)
文摘Objective:To investigate the changes in total phenols,flavonoids,tannins,vitamin E, β-carotene and antioxidant activity during soaking of three white sorghum varieties.Methods: The changes in total phenols,total ilavonoids,tannins,phenolic acids compounds,flavonoid components,vitamin E,P-carotene and antioxidant activity during soaking of sorghum grains were determined.Results:Total phenols,total flavonoids,tannins,vitamin E,P-carotene and antioxidant activity in raw sorghum were ranged from 109.21 to 116.70,45.91 to 54.69,1.39 to 21.79 mg/100 g,1.74 to 5.25,0.54 to 1.19 mg/kg and 21.72%to 27.69%and 25.29%to 31.97%,respectively. The above measured compounds were significantly decreased after soaking.p-Hydroxybenzoic acid,vanillic acid,syringic acid and cinnamic acid represent the major phenolic acids in Dorado variety.While ferulic acid,p-coumaric acid,gallic acid and caffeic acid represent the major phenolic acids in Shandaweel-6.On the other hand,protocatechuic acid represents the major phenolic acids in Giza-15.Regarding flavonoids components,Dorado was the highest variety in kampferol and naringenin while Shandaweel-6 was the highest variety in luteolin, apigenin,hypersoid,quercelin and christen.Finally,Giza-15 was the highest variety in catechin. Phenolic acids,flavonoid compounds and antioxidant activities were decreased after soaking. Conclusions:Sorghum varieties have moderate quantities from total phenols,total flavonoids, tannins,phenolic acids compounds,flavonoid components,vitamin E,P-carotene and antioxidant activity which decreased after soaking.
文摘The stepwise stability constants of coordination compounds from sulfonatedsheoak tannin with metal ions have been determined by pH potential method with catechol asmodel compounds at 20℃and constant ionic strength.
文摘采用控制酯化率和不外加相转移催化剂、在敞开体系中自催化磺化反应的方法,合成了4种不同乙氧基加成数 n(n=3,5,7,9。下同)的阴离子表面活性剂月桂醇聚氧乙烯醚(LEO_n)己基琥珀酸混合双酯磺酸钠(LHSS_n)。对由4种 LEO_n 来分别合成 LHSS_n 的最佳工艺条件与 LEO_n 的乙氧基加成数的关系进行了研究。结果表明:随着乙氧基加成数的增加,单酯化反应的酯化率达到约100%时的反应温度从90℃增加到140℃;双酯化率达到约95%时的反应温度从140℃增加到170℃,己醇过量从100%增加到400%。同样地随着乙氧基加成数的增加,磺化剂亚硫酸氢钠过量从5%增加到10%,反应时间从2.25 h 增加到2.75 h,反应温度从130℃增加到180℃。从酯化反应中 LEO 进攻羰基 C 的空间位阻对酯化反应的影响以及磺化反应中产物自催化作用对磺化反应的影响分别解释了反应性变化的原因。
基金supported by the Institut de la Francophonie pour le Developpement Durable(IFDD/Canada)/Projet de Deploiement des Technologies et Innovations Environnementales(PDTIE)funded by Organisation Internationale de la Francophonie(OIF)the Organisation of African,Caribbean and Pacific States and the European Union(EU)(FED/220/421-370)the Local Materials Promotion Authority(MIPROMALO)of the Ministry of Scientific Research and Innovation of Cameroon who made it possible for this scientific work to be carried out.
文摘Extracts of plant origin,particularly tannins,are attracting growing interest for the sustainable development of materials in the industrial sector.The discovery of new tannins is therefore necessary.The aim of this work was to contribute to the understanding of the properties of Paraberlinia bifoliolata tannin by Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectroscopy MALDI-TOF/MS and Carbon 13 Nuclear Magnetic Resonance(13C NMR).The chemical composition of tannin extracted from Paraberlinia bifoliolata bark was determined,as was the mechanical strength of the resin hardened with Acacia nilotica extracts.Yield by successive water extraction was 35%.MALDI-TOF/MS analysis revealed the presence of three new compounds in this tannin,previously unknown in this family of extracts.These are 3-hydroxyproline acid,N-methyl-4-hydroxypipecolic acid and N-methyl-5-dihydroxypipecolic acid.The identification of the above molecules means that this tannin can be used for industrial applications,as a resin in the manufacture of particleboard and in the formulation of green corrosion inhibitors.This information is reinforced by 13C NMR spectrometry,which indicates the presence of several polyflavonoid units,confirming the condensed nature of the tannin.Thermomechanical analysis of the resin formed by the purified tannin of Paraberlinia bifoliolata to which a vegetal biohardener has been added provided a Modulus of Elasticity(MOE)value of 4840 MPa at 150℃,confirming its possible use as a binder resin in the manufacture of wood panels as well as for the formulation of a corrosion inhibitor.
文摘Objective:To investigate the antioxidant activity,total phenolic and total tannin content of the pericarp and the seed of Coffea benghalensis(C.benghalensis) and Coffea liberica compared to Coffea arabica(C.arabica).Methods:The antioxidant potential,total tannin and polyphenol contents of the immature and mature seed and pericarp of C.benghalensis and Coffea liberica were quantified and compared to C.arabica.Enhanced chemiluminescence(ECL).2,2-diphenyl-1-picrylhydruzyl(DPPH).oxygen radical absorbance capacity,Folin-Ciocaltcau method and total tannin content assays were used.Results:Trolox equivalent(TE/g plant material) values obtained by ECL and DPPH methods showed loose correlation(r^2=0.587)while those measured by oxygen radical absorbance capacity assay were higher without correlation in each plant.A closer correlation was detected between the ECL method and the percentage antioxidant activity of the DPPH technique(r^2=0.610 7) in each species,however the immature pericarp of C.benghalensis showed much higher DPPH scavenging potential than was seen in the ECL assay.The immature pericarp of C.benghalensis expressed the highest tannin and polyphenol content,and a high polyphenol level was also detected in the immature seed of C.arabica.The immature pericarp of Bengal and Liberian coffees showed the largest amount of phenolic contents.Conclusions:The obtained data highlight the potential role of C.benghalensis as a new source of natural antioxidants and polyphenols compared to C.arabica.
