Culm in Rice Straw as a New Source for Sugar RecoveryviaEnzymatic Saccharification

Abstract

Rice straw was manually dissected and two main fractions were recovered: a culm and a leaf sheath/blade fraction, in order to evaluate their potential as feedstocks for the recovery of fermentable sugars. In the case of cv. Koshihikari and Milkyqueen, most soft carbohydrates (SCs: glucose, fructose, sucrose, starch, and beta-1,3-1,4-glucan) were present in the culms, reaching 47.9% and 89.2% of total SCs in the two main fractions. The results also indicated that beta-glucans (cellulose and beta-1,3-1,4-glucan) and xylan in the culms were more susceptible to direct enzymatic attack than those in the leaf sheath/blades. Thus the culm has high potential as a new feedstock for the extraction of fermentable sugars in a concentrated form, as compared to whole rice straw and the leaf sheath/blade. In this study, a novel method of separating a culm from the whole rice straw by means of wind power was also evaluated.

DiSC (direct saccharification of culms) process for bioethanol production from rice straw

“…Meanwhile, recent analyses of the carbohydrate components of rice straw demonstrated that this feedstock possesses a remarkable advantage over other agricultural wastes in that it often contains so-called soft carbohydrates (SCs: glucose, fructose, sucrose, starch and b-1,3-1,4-glucan), as well as cellulose and xylan (Park et al, 2009(Park et al, , 2010a(Park et al, , 2010bShiroma et al, 2011). In some cases, the amounts of SCs in rice straw are larger than the cellulose content.…”

“…Harsh pretreatment for cell walls could over degrade some SCs (mainly fructose residues or reducing sugars, depending on the chemicals and heat conditions) (Park et al, 2010a). In addition, solid-liquid separation processes after some pretreatments, which are often used for pH neutralization and reagent recovery/ removal, would remove some SCs after the pretreatments (Park et al, 2010b).…”

Alkali Pretreatment of Wheat Straw (Triticum aestivum) at Boiling Temperature for Producing a Bioethanol Precursor

“…1) Bioethanol is considered an important alternative to gasoline for transportation, because it can reduce the emission of CO 2 which contributes to the global greenhouse effect. 2) To address global warming and safeguard global energy issues, it is alluring to produce bioethanol from lignocellulosic biomass to avoid competition between food and fuel production.…”

Characterization of Starch Granules in Rice Culms for Application of Rice Straw as a Feedstock for Saccharification

“…17) In the case of cultivars Koshihikari and Milkyqueen, most of the SCs including starches at the mature stage were present in the culms, reaching 47.9% and 89.2% of the total SCs in the straw. 18) Together with the results indicating that -glucans and xylans in the culms are more susceptible to enzymatic attack, culms show high potential as a feedstock for the extraction of fermentable sugars. 18) Hence we focused on the culms as a source of starch.…”

“…18) Together with the results indicating that -glucans and xylans in the culms are more susceptible to enzymatic attack, culms show high potential as a feedstock for the extraction of fermentable sugars. 18) Hence we focused on the culms as a source of starch.…”