Quercus suber and Betula pendula outer barks as renewable sources of oleochemicals: A comparative study

TLDR: A comparative study on the chemical composition of oak cork and corresponding industrial residues and birch ( Betula pendula L.) outer bark is reported in this article, which revealed that C18 and C22 ω-hydroxyfatty acids (including mid-chain epoxy- and dihydroxy-derivatives), followed by α,ω-dicarboxylic acids, are the main components in both suberins.

About: This article is published in Industrial Crops and Products.The article was published on 2009-01-01 and is currently open access. It has received 112 citations till now. The article focuses on the topics: Quercus suber & Suberin.

Figures

Table 4 – Main dep-suberin monomers of ICP, BoB and QsC isolated by alkaline hydrolysis and methanolysis identified by

Fig. 1 – Comparison of depolymerized cork and birch outer bark suberin acid composition by GC–MS.

Table 2 – Cellulose and non-cellulosic carbohydrates, in

Table 3 – Monosaccharide composition of non-cellulosic carbohydrates (by acid methanolysis and GC), % of

Table 1 – Group composition (wt.%) of Betula pendula

Fig. 2 – Structures of the most abundant components identified in dep-suberin samples.

Frequently asked questions

Q1. What have the authors contributed in "Quercus suber and betula pendula outer barks as renewable sources of oleochemicals: a comparative study" ?

A comparative study on the chemical composition of oak cork ( Quercus suber L. ) and corresponding industrial residues and birch ( Betula pendula L. ) outer bark is reported. Analysis of the suberin monomeric composition revealed that C18 and C22 -hydroxyfatty acids ( including mid-chain epoxyand dihydroxy-derivatives ), followed by, -dicarboxylic acids, are the main components in both suberins, with 9,10-epoxy-18-hydroxyoctadecanoic, 18-hydroxyoctadec-9-enoic, 9,10,18-trihydroxyoctadecanoic and octadec-9-enoic acids as the major components. The differences in the relative amounts of these acids in the suberin samples and the impact on the potential exploitation of the different industrial by-products are discussed. 

Q2. What are the future works in "Quercus suber and betula pendula outer barks as renewable sources of oleochemicals: a comparative study" ?

In the case of cork, the yields of dep-suberin isolation and the amounts of compounds are smaller than for birch, and there is not a dominant component ( excepting for 22-hydroxydocosanoic acid in methanolysis dep-suberin ) that could justify further working up of the extract to isolate it in a pure state. In this case, the exploitation of dep-suberin will certainly pass through the direct processing of the entire mixture, possibly after a purification step to separate suberin monomers from the undetected fraction. The even lower amounts of monomers detected in the dep-suberin obtained by methanolysis suggests that this depolymerization pathway is of interest only if the monomers are required in methyl ester form ( e. g., for polyester synthesis through transesterification ), or for the isolation of 22- hydroxydocosanoic acid, the dominant component detected in this fraction. 

Q3. What is the abundant component in the dep-suberin extract?

For BoB, the most abundant component is 9,10-epoxy-18-hydroxyoctadecanoic acid (99 mg/g), which accounts for about 37% of the identified components, followed by 22-hydroxydocosanoic (42 mg/g), 18-hydroxyoctadec-9enoic (39 mg/g) and 9,10,18-trihydroxyoctadecanoic acid(29 mg/g), with this last component resulting from the cleavage of the corresponding epoxide. 

Q4. What is the predominant non-cellulosic sugar in the cork?

Xylose was the dominating non-cellulosic sugar in both cork samples, indicating the presence of xylans, as previously suggested (Asensio, 1987a,b). 

Q5. What was the total amount of carbohydrates in the studied samples?

The non-cellulosic carbohydrates, most probably originating mainly from hemicelluloses, were calculated as the total sum of sugars from acid methanolysis. 

Q6. How many ton of birch bark is produced annually in Finland?

Based on birch kraft pulp production figures, the total potential of birch outer bark in Finland can be estimated to be 200,000 ton/year (Paper and wood insights, 2006). 

Q7. What is the successful biorefinery of the future?

Among these biorefineries of the future, the lignocellulosic feedstock (LCF) biorefineries, will probably be the most successful, on the one hand, because of the availability of feedstocks (both ded-0926-6690/$ – see front matter © 2008 Elsevier B.V. 

Q8. What was the reaction used for the analysis of the depsuberins?

The monosaccharide alditol acetates were analyzed by GC using a Varian 3350 GC, following previously described chromatographic conditions (Pinto et al., 2005). 

Q9. How much is the birch kraft pulp mill producing?

a birch kraft pulp mill, with an annual pulp production of 400,000 ton/year generates about 28,000 ton of outer bark (Ekman, 1983), which is, at the present, burnt in the biomass boilers of kraft pulp mills for energy production.