Biorefining strategy for maximal monosaccharide recovery from three different feedstocks: Eucalyptus residues, wheat straw and olive tree pruning

Abstract

h i g h l i g h t sER, WS and OP are suitable feedstocks for Southern European biorefineries. The proposed biorefining strategy is efficient for monosaccharide recovery. Maximal monosaccharide recovery was obtained after autohydrolysis at 210°C. Maximal cellulose enzymatic digestibility was obtained after autohydrolysis at 230°C. The conditions for maximal sugar recovery yield were similar for all feedstocks. This work proposes the biorefining of eucalyptus residues (ER), wheat straw (WS) and olive tree pruning (OP) combining hydrothermal pretreatment (autohydrolysis) with acid post-hydrolysis of the liquid fraction and enzymatic hydrolysis of the solid fraction towards maximal recovery of monosaccharides from those lignocellulose materials. Autohydrolysis of ER, WS and OP was performed under non-isothermal conditions (195-230°C) and the non-cellulosic saccharides were recovered in the liquid fraction while cellulose and lignin remained in the solid fraction. The acid post-hydrolysis of the soluble oligosaccharides was studied by optimizing sulfuric acid concentration (1-4% w/w) and reaction time (10-60 min), employing a factorial (2 2 ) experimental design. The solids resulting from pretreatment were submitted to enzymatic hydrolysis by applying commercial cellulolytic enzymes Celluclast Ò 1.5 L and Novozyme Ò 188 (0.225 and 0.025 g/g solid, respectively). This strategy provides high total monosaccharide recovery or high glucose recovery from lignocellulosic materials, depending on the autohydrolysis conditions applied.

Autohydrolysis of Annona cherimola Mill. seeds: Optimization, modeling and products characterization

“…it is significantly higher than the glucose yieldreported for eucalyptus residues (54%), and close to 82% for olive tree pruning, and only slightly lower for straws (88, 90 and 91 %, respectively for rice, corn straw and wheat straw) [37][38][39], what may be explained by the higher lignin content of the cherimola seed cake as compared to straws.Although, it is reported that the highest glucose yield can only be achieved after the complete removal of hemicellulose, the lignin also plays a role on preventing cellulose hydrolysis that must not be neglected [22].…”

Physico-chemical pretreatment technologies of bioconversion efficiency of Paulownia tomentosa (Thunb.) Steud.

“…Paulownia tomentosa 41.7 ± 0.5 19.8 ± 0.3 61.5 20.5 ± 0.8 Paulownia fortune (Caparros et al, 2008) 34.2 22.7 56.9 27.2 Eucalyptus grandis (Castoldi and Bracht, 2014) 42 ± 4 19 ± 2 61.6 23 ± 2 Eucalyptus globulus (Ishiguro and Endo, 2015) 34.0 18.2 52.2 33.3 Eucalyptus residues (Silva-Fernandes et al, 2015) 36.1 ± 0.6 23.8 ± 0.8 59.9 26.7 ± 0.3 Bamboo timber (Xin et al, 2015) 39.36 ± 0.76 18.01 ± 0.06 57.37 20.83 ± 0.13 Bamboo knot (Xin et al, 2015) 39.90 ± 0.51 18.42 ± 0.55 58.32 21.90 ± 0.70 Water hyacinth (Poddar et al, 1991) 25.61 18.42 44.03 9.93 Water hyacinth (Chanakya et al, 1996) 33.97 18 51.97 26.36 Olive tree pruning (Silva-Fernandes et al, 2015) 24.5 ± 0.2 18.8 43.3 22.2 ± 0.2 Wheat straw (Toquero and Bolado, 2014) 35.19 ± 0.29 22.15 ± 0.21 57.34 22.09 ± 0.31 Corn stover 32.92 ± 0.51 16.53 ± 0.24% 49.45 17.36 ± 0.28 USA) after a two-section acid hydrolysis. Total reducing sugars in prehydrozate and hydrozate were determined by the DNS Method using glucose as the standard (Miller, 1959).…”

The influence of free-living nitrogen-fixing bacteria on the mechanical characteristics of different plant residues under no-till and strip-till conditions

“…The samples collected were weighed and dried in an oven at 105 C until constant mass (Fallahi and Raoufat, 2008;Wood et al, 2014;Silva-Fernandes et al, 2015). And after that their moisture contents were calculated.…”