Hydrolysis of wheat straw hemicellulose with trifluoroacetic acid. Fermentation of xylose with Pachysolen tannophilus

Abstract

Treatment of wheat straw with 1N trifluoroacetic acid (TFA) for 7 h at reflux temperature yielded 23% xylose based upon initial straw weight. This corresponds to about an 80% xylose yield based on the xylan content of the hemicellulose. The cellulose component of wheat straw was largely unaffected, as evidenced by low glucose yields. Decomposition of xylose by prolonged refluxing (23 h) was minimal in 1N TFA compared to 1N HCl. Treatment of wheat straw with refluxing 1N TFA converts about 10% of the lignin initially present in straw into water‐soluble lignin fragments. Fermentation of the xylose‐rich wheat straw hydrolyzate to ethanol with Pachysolen tannophilus was comparable to the fermentation of reagent grade xylose, indicating that furfural and toxic lignin by‐products were not produced by 1N TFA in sufficient amounts to impair cell growth and ethanol production. Cellulase treatment of the wheat straw residue after TFA hydrolysis resulted in a 70–75% conversion of the cellulose into glucose.

Sugarcane bagasse hydrolysis with phosphoric and sulfuric acids and hydrolysate detoxification for xylitol production

“…Average increases in acetic acid and HMF concentrations of about 1.0 g dm −3 and 0.06 g dm −3 , respectively, were observed in the hydrolysates when the residence time was extended from 20 to 60 min. A similar result was observed by Fanta et al 13 when increasing the reflux time during the hydrolysis of wheat straw hemicellulose with trifluoroacetic acid. Although the furfural concentration in the different hydrolysates ranged between 0.03 and 0.40 g dm −3 , the Student's t-test revealed that none of the independent variables influenced this response significantly (data not shown).…”

Fermentation of acid hydrolysates from olive-tree pruning debris by Pachysolen tannophilus

“…This fact can be explained accepting a smaller inhibition or toxicity in the fermentations of the hydrolysates obtained with this acid. In agreement with Fanta et al [7] with trifluoroacetic acid, very low concentrations of furfural and other products form from lignin degradation.…”

“…In this work, we have used intermediate conditions, since that we wish to prevent the formation of degradation products at concentrations that can inhibit the subsequent fermentation process. The acid most employed is H 2 SO 4 although other acids can be used such as HCl [5], HNO 3 [6], CF 3 -COOH [7] or H 3 PO 4 [8].…”

Kinetics of ethanol production from D‐xylose by the yeastpichia stipitis

“…The rates of substrate consumption and ethanol production are significantly higher with glucose, compared to xylose as carbon source. On the other hand the yield coefficients of ethanol and of cell mass are comparable on both sugars and are significantly higher than the figures reported by other authors (Detroy et al, 1982;Fanta et al, 1984).…”