Fate of p-hydroxycinnamates and structural characteristics of residual hemicelluloses and lignin during alkaline-sulfite chemithermomechanical pretreatment of sugarcane bagasse

Table 3 Hydroxycinnamic acids detected in sugarcane bagasse before and after pretreatment via an alkaline-sulfite chemithermomechanical process or chlorite delignification

Sample	Hydroxycinnamic acids (g/100 g of pretreated bagasse)				Solids yield (%)	Mass balance (g/100 g of original bagasse)
	Mild hydrolysis		Severe hydrolysis			Mild hydrolysis		Severe hydrolysis
	Ferulic	p-Coumaric	Ferulic	p-Coumaric		Ferulic	p-Coumaric	Ferulic	p-Coumaric
Untreated	0.28 ± 0.03	1.14 ± 0.08	1.5 ± 0.1	3.7 ± 0.4	100	0.28	1.14	1.5	3.7
2.5% Na₂SO₃ + 1.25% NaOH	0.20 ± 0.03	1.1 ± 0.1	1.2 ± 0.4	4.4 ± 0.3	86.8	0.17	0.94	1.1	3.8
5% Na₂SO₃ + 2.5% NaOH	0.11 ± 0.01	0.80 ± 0.05	1.4 ± 0.1	2.7 ± 0.3	84.1	0.09	0.67	1.2	2.3
10% Na₂SO₃ + 5% NaOH	0.11 ± 0.01	0.11 ± 0.03	0.7 ± 0.1	1.9 ± 0.4	81.8	0.09	0.09	0.6	1.5
Chlorite-delignified sample	0.08 ± 0.01	nd	0.16 ± 0.01	0.02 ± 0.03	85.7	0.06	nd	0.13	0.02

ISSN: 2731-3654