twin-screw-extrusion-process-to-produce-renewable-fiberboards

Twin-Screw Extrusion Process to Produce Renewable Fiberboards

A versatile twin-screw extrusion process to provide an efficient thermo-mechano-chemical pre-treatment on lignocellulosic biomass before using it as ...

Université de Toulouse, INRAE, INPT

The aim of this article is to compare two different sets of optimal conditions for twin-screw extraction of xylans and define their influence on the purification steps, combining ultrafiltration and industrial chromatography. Two xylan extracts were obtained by twin-screw extrusion of straw and bran. Condition 1 used a high straw/bran ratio (equal to 6) and high sodium hydroxide content, and condition 2 used a lower straw/bran ratio (equal to 2) and low sodium hydroxide content. Arabinoxylan extraction yields are slightly higher for conditions with low straw content (5.1% versus 4.4%). Nevertheless, these recovery yields remain between 9% and 10%. Ultrafiltration is as efficient as evaporation for polysaccharide concentration, with lower energy consumption, but also demineralizes the solution. The combination of ultrafiltration and chromatography gives partial purification of the extract with a final arabinoxylan purity ranging from 16% to 26%. This is slightly higher than by direct precipitation, but limited because all the large molecules such as proteins and lignins were retained by ultrafiltration. 

Comparison of different twin-screw extraction conditions for the production of arabinoxylans.

Microscopic observation of sunflower meal before and after extraction indicated that extensive cellular disruption was achieved by extrusion, but that unextracted oil remained sequestered as coalesced oil within the void spaces of disrupted cotyledon cells. A full factorial design experiment was defined to develop aqueous extraction processing (AEP) with and without enzymes to improve vegetable oil extraction yields of extruded sunflower meal. This experimental design studied the influence of four parameters, agitation, liquid/solid (L/S) ratio, and cellulase and protease addition, on extraction yield of lipid and protein. Agitation and addition of cellulases increased oil extraction yield, indicating that emulsification of oil and alteration of the geometry of the confining cellular matrix were important mechanisms for improving yields. Protease and liquid-solid ratio of the extraction mixture did not have significant effects, indicating key differences with previously established soy oil extraction mechanisms. Maximum yields attained for oil and protein extraction were 39% and 90%, respectively, with the aid of a surfactant. 

Article	Year
Comparison of different twin-screw extraction conditions for the production of arabinoxylans. Carbohydrate polymers\| PubMed ID: 25458276	2015
Parameters affecting enzyme-assisted aqueous extraction of extruded sunflower meal. Food chemistry\| PubMed ID: 27132846	2016

Pierre-Yves Pontalier

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