Sequential Enzymatic and Mild-Acid Hydrolysis of By-Product of Carrageenan Process from Kappaphycus alvarezii

• Published in: Bioenergy research 2019-06, Vol.12 (2), p.419-432
• Main Authors: Paz-Cedeno, Fernando Roberto, Solórzano-Chávez, Eddyn Gabriel, de Oliveira, Levi Ezequiel, Gelli, Valéria Cress, Monti, Rubens, de Oliveira, Samuel Conceição, Masarin, Fernando
• Format: Article
• Language: English
• Subjects: Acids; Algae; Biofuels; Biological products; Biomedical and Life Sciences; Byproducts; Carrageenan; Carrageenin; Conversion; Enzymes; Ethanol; Fermentation; Fine chemicals; Galactose; Glucan; High temperature; Hydrolysis; Independent variables; Kappaphycus alvarezii; Life Sciences; Organic chemistry; Plant Breeding/Biotechnology; Plant Ecology; Plant Genetics and Genomics; Plant Sciences; Seaweeds; Selectivity; Statistical analysis; Sugar; Wood Science & Technology
• ISSN: 1939-1234; 1939-1242
• DOI: 10.1007/s12155-019-09968-7

Kappaphycus alvarezii is a red macroalgae widely used to produce carrageenan. The carrageenan processing produces a by-product rich in glucan which has been reported as easily hydrolyzed with enzymes, but the hydrolysate forms a gel at usual fermentation temperatures. The purpose of this study was to evaluate the enzymatic hydrolysis integrated with a mild-acid treatment of the by-product to obtain a hydrolysate rich in monomeric sugars. Using an enzyme load of 10 FPU g −1 of by-product, close to 100 and 14.7% of glucan and galactan conversion were reached, respectively. Increasing the enzyme load to 100 FPU g −1 raised the galactan conversion to 30%. The mild-acid treatment after enzymatic hydrolysis was satisfactory, increasing the glucose and galactose concentrations, without producing significant amounts of fermentation inhibitors and avoiding the formation of a gel structure. The statistical analysis showed that the main effects on the response were negative for the three independent variables, meaning that the selectivity ( S ) becomes lower when experimental conditions at the higher levels are used (longer time, higher temperature, and acid concentration). Therefore, the integrated enzymatic and acid hydrolysis of the by-product becomes a promising technological route to produce monomeric sugars for bioethanol or fine chemical production.