Fig. 5

Hypothetical structures of xylan fragments extracted from sugar cane. It is based on the monosaccharide analysis (see Table 6) and assuming glycoside bonds common in different types of xylan. The backbone is linked by β-(1–4) glycosidic bonds; arabinoses can be linked to the xylan backbone by α-(1–2) or α-(1–3) bonds; while, glucuronic acids are linked by α-(1–2) bonds. Notice that the branching pattern is affected by the extraction conditions. A Extraction with 0.5 M NaOH for 60 min. B Pressurized liquid extraction (experiment No.4). C Extraction with 2 M NaOH in a single or two cycles. D Extraction with 2 M NaOH and in three cycles