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- Distillery residues from Cistus ladanifer (Rockrose) as feedstock for the production of added-value phenolic compounds and hemicellulosic oligosaccharidesPublication . Alves Ferreira Caturra, Júnia Aparecida; Duarte, Luís C.; Lourenço, Ana; Roseiro, Luisa B.; C. Fernandes, M.; Pereira, Helena; Carvalheiro, FlorbelaABSTRACT: Cistus ladanifer residues obtained after essential oil distillation were extracted with ethanol and water (CLRext) and subsequently hydrothermally treated (autohydrolysis) in order to selectively hydrolyze hemicelluloses. The extraction removed a significant amount of potentially valuable compounds (40% w/w, dry basis), foremost, phenolic compounds (0.363 and 0.250 g gallic acid equivalent/g extract, respectively, for water and ethanol). Autohydrolysis was studied under diverse severity factors (log R-o), in the temperature range of 150 to 230 degrees C. The hydrolyzates mainly contain oligosaccharides, reaching the highest concentration (23.5g/L) for log R-o of 3.07 (190 degrees C), corresponding to a yield of 15g oligosaccharides/100g dry feedstock. The processed solids are enriched in glucan and lignin. The maximum glucan content (35%) was attained at log R-o of 3.51 (205 degrees C). Py-GC/MS confirmed the reduction of pentose-derived carbohydrates in the solid after hydrothermal treatment and an increase of syringil units in the lignin compared to the untreated biomass. These results show the potential use of this C. ladanifer residue for the production of phenolic extracts, and hemicellulosic oligosaccharides, together with the production of a cellulose- and lignin-rich solid stream.
- Cistus ladanifer as a source of chemicals : structural and chemical characterizationPublication . Alves Ferreira Caturra, Júnia Aparecida; Miranda, Isabel; Duarte, Luís C.; Roseiro, Luisa B.; Lourenço, Ana; Quilhó, Teresa; Cardoso, Sofia; Fernandes, M. C.; Carvalheiro, Florbela; Pereira, HelenaABSTRACT: Different biomass fractions of Cistus ladanifer and solid residues from essential oil distilleries were structurally and chemically evaluated. The C. ladanifer biomass fractions showed chemical differences mainly related to extractives (e.g., 10.8% and 53.7% in stems and leaves) and lignin (e.g., 21.2% and 15.4% in stems and leaves). The distillery residues were characterized by 41.5% extractives and 19.3% lignin, and polysaccharide glucose 51.7% and xylose 24.9% of total monosaccharides. The polar extracts had a high content of phenolics and revealed high antioxidant activity (IC50 3.2 μg/mL and 4.7 μg/mL in stems and cysts extracts). The lignin structure showed a predominance of S units in the stem (H:G:S of 1:25:50) and a balanced proportion of H, G, and S units in leaves (H:G:S of 1:1.4:1). The characteristics of C. ladanifer biomass allow several routes of valorization. The high extractive contents point out to the potential use as a source of phytochemicals by applying extraction procedures, while the remaining lignocellulosic material after extraction may be directed towards lignin and carbohydrates applications. The use of C. ladanifer biomass for an extractives-lignocellulosic-based biorefinery therefore represents a potential valorization that may contribute to additional revenue for the present essential oil distilleries.