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| Pretreatment techniques | Biomass | Required condition | Degradation in cellulose & hemicellulose | Major findings | Ref. |
|
| Steam explosion | Defatted soyabean meal | 1.5 Mpa/193.1°C for 5 min | Cellulose-50.7%
Hemicellulose-71.1% | At high pressure, biomass saturated with water vapour, the fiber network gets relaxed and lignin content migrates | [16] |
| Steam explosion +1%, , dil. H2SO4 | Rice straw (10 mm particle size) | 200°C for 10 min | Glucan conversion to 89.6% | Large particle size consumes less energy & low production cost | [34] |
| Steam explosion | Miscanthus | 200°C, 15 bar, 10 min | Xylo-oligosaccharide yield 55%, | Larger biomass (10-30 mm) particles led to higher XOS yield (55%, ) | [35] |
| Steam explosion +0.8% NaOH +1.2% w/v CaO | Corn stalk | 2.4 gm NaOH, 3.60 gm CaO in 5 : 1 ratio (), 130 kPa pressure for 1 hr | 54.7% reducing sugar yield | CrI has increased little due to an increase in the order of amorphous cellulose and degree of freedom | [42] |
| Steam explosion +0.5% H2SO4 | Rice straw | 200°C/100 bar/10 min | Increase sugar concentration to 12.4 g/l | Max. Sugar yield 86% | [47] |
| Steam explosion & catalysed with H3PO4 & H2SO4 | Sugarcane bagasse | 195°C for 7.5 min | 69.4% of free sugar released after pretreatment | Maximum mass recovery in presence of acid catalysts and higher xylan content up to 6.6 wt.% | [48] |
| Steam explosion + sulphonation (Na2SO3,12%, + NaHCO3, 4%, ) | Woody Eucalyptus | 210°C for 5 min | Glucan hydrolysis increased to 57.89% from 12.23% | Solubilization of hemicellulose
Hydrolysis yield was higher at 210°C as compared to 200°C steam | [50] |
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