Fragmentation of Suberin and Composition of Aliphatic Monomers Released by Methanolysis of Cork from Quercus suber L.,Analysed by GC-MS, SEC and MALDI-MS

Holzforschung ◽  
2001 ◽  
Vol 55 (5) ◽  
pp. 487-493 ◽  
Author(s):  
M.F. Bento ◽  
H. Pereira ◽  
M.Á. Cunha ◽  
A.M.C. Moutinho ◽  
K.J. van den Berg ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Ferulic Acid ◽  
Quercus Suber ◽  
Maldi Ms ◽  
Hydroxy Acids ◽  
Sodium Methanolate ◽  
Reactant Concentration ◽  
Alkanoic Acids ◽  
Monomeric Composition

Summary Suberin from extractive-free cork from Quercus suber L. was depolymerised by methanolysis using different sodium methanolate (NaOMe) concentrations. 1% and 3% NaOMe completely removed suberin from cork (54%–56% of extractive-free cork), but for lower concentrations there was incomplete solubilisation; with 0.05% NaOMe, only approximately 80% of total suberin was removed. The monomeric composition of the extracts differed significantly: for the 0.05% NaOMe, only alkanoic acids and diacids were found; the yield of v-hydroxy acids increased with reactant concentration, as well as alkanols and ferulic acid. Results from light scattering, SEC and MALDI-MS showed that soluble oligomeric fragments containing suberinic acids were present in the methanolysis mixture. The molecular weight of these oligomeric fragments decreased with higher sodium methanolate concentrations.

Variability of Suberin Composition of Reproduction Cork from Quercus suber Throughout Industrial Processing

Holzforschung ◽  
1999 ◽  
Vol 53 (1) ◽  
pp. 56-62 ◽  
Author(s):  
E. Conde ◽  
M. C. García-Vallejo ◽  
E. Cadahía
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Sodium Methoxide ◽  
Quercus Suber ◽  
The Other ◽  
Gas Chromatography Mass Spectrometry ◽  
Industrial Processing ◽  
Alkanoic Acids ◽  
Monomeric Composition ◽  
Store Room

Summary The chemical composition of suberin was studied in cork planks from three different trees of Spanish Quercus suber at four different stages of the industrial processing of first transformation: stripping (a), first rest (b), boiling followed by open air rest (c1) and boiling followed by store-room rest (c2). The monomeric composition was determined by gas chromatography/mass spectrometry in the product of depolymerization of the free of extractives cork with sodium methoxide-methanol. The average concentrations of the main monomers were: 1-alkanols (C20–C26) 4.17 %; alkanoic acids (C20–C26) 5.99%; α, ω-alkanedioic acids (C16–C24) 6.20%; ω-hydroxy-alkanoic acids (C20–C26) 29.41%; erythro and threo-9,10-dihydroxyoctadecanedioic acids 6.76%, erythro- and threo-9,10,18-trihydroxyoctadecanoic acids 9.50%, 9,10-epoxy-18-hydroxyoctadecanoic acid 2.72% and 9,10-epoxy-octadecanedioic acid 2.93% and ferulic acid 5.05%. Significant differences were observed between samples taken at the stripping and after boiling with store room rest, and both groups of samples differed from those picked after the other two processing stages. Ten components were selected as providing the greatest discrimination among stages: 9-octadecenedioic, 18-hydroxy-9-octadecenoic, eicosanedioic and 9,10-epoxy-18-hydroxy-octadecanoic acids, tetracosanol, and five unidentified components.

scholarly journals A study of the application of graphite MALDI to the analysis of short-chain polyethylene glycols

2021 ◽  
Author(s):  
Ulric Conway ◽  
Alexander D. Warren ◽  
Christopher J. Arthur ◽  
Paul J. Gates
Keyword(s):  
Molecular Weight ◽  
Lithium Chloride ◽  
Maldi Ms ◽  
Short Chain ◽  
Polyethylene Glycols ◽  
Low Molecular Weight ◽  
Colloidal Graphite ◽  
Graphite Matrix ◽  
Successful Analysis

MALDI-MS using colloidal graphite matrix doped with lithium chloride for the successful analysis of low molecular weight polymers.

Characterization of water soluble pentosans of enzyme supplemented dough and breads/ Caracterización de las pentosanas solubles en agua extraídas de masa y pan conteniendo enzimas comerciales

2000 ◽  
Vol 6 (3) ◽  
pp. 197-205 ◽  
Author(s):  
T. Jimenez ◽  
M.A. Martinez-Anaya
Keyword(s):  
Molecular Weight ◽  
Ferulic Acid ◽  
Synergistic Effects ◽  
Extraction Yield ◽  
Water Soluble ◽  
Sugar Composition ◽  
Enzyme Preparations ◽  
Processing Enzyme ◽  
Enzyme Source

Water soluble pentosans (WSP) from doughs and breads made with different enzyme preparations are characterized according to extraction yield, sugar composition, xylose/arabinose ratio and molecular weight (MW) distribution. Extraction yield was greater for dough than for bread samples, ranging from 0.94 to 1.64%, but bread extracts had a higher purity. Percent of pentoses in purified WSP was greater in pentosanase supplemented samples (28-55%) than in control and amylase containing samples (23-32%). Major sugars were xylose and arabinose, but glucose and mannose also appeared in the extracts. The xylose/arabinose (Xyl/Ara) ratio was 1.3-1.6 and underwent small changes during processing. Enzyme addition caused an increase in Xyl/Ara ratio, attributable to a debranching of arabinoxylans (AX) with higher degree of Ara substitution by arabinofuranosidase. Addition of pentosanases had a significant effect in increasing WSP with MW over 39 000, whereas those of low MW changed only slightly. MW distribution depended on enzyme source, and whereas some enzymes showed activity during fermentation others increased their activity during baking. No synergistic effects were observed in studied variables due to the combination of amylases with pentosanases. Protein in WSP extracts eluted together with ferulic acid suggesting they were linked, but not associated with a determined carbohydrate fraction.

A light-scattering study of the effect of calcium chloride on the molecular weight of busycon hemocyanin

1978 ◽  
Vol 8 (2) ◽  
pp. 133-138 ◽  
Author(s):  
M.Constance Loeffler ◽  
Shian-shi Su ◽  
Norman C. Li ◽  
Edward F. Casassa
Keyword(s):  
Molecular Weight ◽  
Light Scattering ◽  
Calcium Chloride ◽  
Scattering Study
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