Comprehensive analysis of sugarcane bagasse steam explosion using autocatalysis and dilute acid hydrolysis (H₃PO₄ and H₂SO₄) at equivalent combined severity factors

Steam explosion of sugarcane bagasse was carried out in the absence (autocatalysis) and presence of dilute phosphoric (H₃PO₄) and dilute sulfuric (H₂SO₄) as exogenous acid catalysts. Seven experiments were designed to operate at the same combined severity factor (CSF) of 0.76 ± 0.02: three autocatalytic steam explosion (steam-exploded bagasse, SEB), three with dilute H₂SO₄ (SEB/SA) and one with dilute H₃PO₄ (SEB/PA) that was used as reference. Steam treatment at the same CSF produced substrates with similar chemical compositions, rheological behaviors and glucose yields by enzymatic hydrolysis at 15% total solids (TS) using Cellic CTec3, except for two SEB/SA experiments that were carried out at lower temperatures and shorter times. SEB were the best substrates because they required the lowest power consumption for hydrolysis at 15% TS compared to SEB/SA and SEB/PA. Carbohydrates, aliphatic acids, furans and aromatic compounds were also characterized in pretreatment water-solubles by GC–MS and these varied considerably regardless of their equivalence in pretreatment CSF.