Twin-screw extrusion for hemicellulose recovery: Influence on extract purity and purification performance

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

“…It has been shown in previous studies that straw is mainly added to improve liquid-solid separation, and so the source of extracted molecules is mainly the bran, pre-soaked in soda 1 h before extrusion, (Zeitoun et al, 2010;Jacquemin, Zeitoun, Sablayrolles, Pontalier, & Rigal, 2012). However, after extraction, slight differences can be observed between the composition of the straw and the refined straw fibres produced during extrusion (Table 3).…”

“…The 52 cm long, 5.4 cm external diameter module was composed of 1300, 0.5 mm-diameter polyethersulfone hollow fibres, (GE Healthcare, UFP-30-C9A). This membrane was selected in the light of previous results (Zeitoun et al, 2010) as discussed in Section 3. The filtration apparatus used a 36 L capacity feed reservoir, a rheostat controlled bilobal-pump, a filtration cartridge and a pressure gauge allowing manual membrane pressure adjustment.…”

“…There were two reverse-pitch screw elements with grooved peripheral slots in the screw for leakage flow, and a series of 1 cmlong neutral pitch bilobal elements splayed at 90 degrees to each other, were used to knead the plant matter. The 10 cm-long filter element mounted on the last section, was perforated with conical holes (1 mm inlet, 2 mm outlet) and was used to optimize solid/liquid separation (Zeitoun et al, 2010). One hour before extrusion, wheat bran and sodium hydroxide were blended at room temperature, giving a liquid/solid ratio of 7, adjusted to 10 just before the extrusion.…”

“…Nonetheless, even if only a few studies have dealt with pilot scale extraction of hemicelluloses (Annison, Choct, & Cheethamet, 1992;Bataillon et al, 1998;Zeitoun, Pontalier, Maréchal, & Rigal, 2010;Montané, Farriol, Salvado, Jollez, & Chornet, 1998), it needs to be developed on an industrial scale (Puls & Saake, 2004). As twinscrew extrusion is a continuous process, which could be scaled up to an industrial scale, it was investigated for straw/bran co-extraction using sodium hydroxide.…”

“…As twinscrew extrusion is a continuous process, which could be scaled up to an industrial scale, it was investigated for straw/bran co-extraction using sodium hydroxide. This technique combines chemical, thermal and mechanical actions to remove the dissolved molecules from the plant tissue by continuous squeezing in a screw press (Zeitoun et al, 2010), and it has proved to be an efficient method for alkaline extraction of hemicelluloses from wheat bran (Maréchal, Jorda, Pontalier, & Rigal, 2003). It gives lower extraction yields and selectivity than batch extraction but has the advantage of being continuous and requiring smaller quantities of reagents and water (Montané et al, 1998;Maréchal et al, 2003).…”