Authors: Carvalheiro, Florbela¹; Duarte, Luís¹; Medeiros, Raquel¹; Gírio, Francisco²

Source: Applied Biochemistry and Biotechnology, Volume 115, Numbers 1-3, March 2004 , pp. 1059-1072(14)

Publisher: Humana Press

Abstract:

Dilute-acid hydrolysis of brewery's spent grain to obtain a pentose-rich fermentable hydrolysate was investigated. The influence of operational conditions on polysaccharide hydrolysis was assessed by the combined severity parameter (CS) in the range of 1.39-3.06. When the CS increased, the pentose sugars concentration increased to a maximum at a CS of 1.94, whereas the maximum glucose concentration was obtained for a CS of 2.65. The concentrations of furfural, hydroxymethylfurfural (HMF), as well as formic and levulinic acids and total phenolic compounds increased with severity. Optimum hydrolysis conditions were found at a CS of 1.94 with >95% of feedstock pentose sugars recovered in the monomeric form, together with a low content of furfural, HMF, acetic and formic acids, and total phenolic compounds. This hydrolysate containing glucose, xylose, and arabinose (ratio 10:67:32) was further supplemented with inorganic salts and vitamins and readily fermented by the yeast Debaryomyces hansenii CCMI 941 without any previous detoxification stage. The yeast was able to consume all sugars furfural, HMF, and acetic acid with high biomass yield, 0.68C-mol/C-mol, and productivity, 0.92 g/(L·h). Detoxification with activated charcoal resulted in a similar biomass yield and a slight increase in the volumetric productivity (11%).

Keywords: Brewery's spent grain; dilute-acid hydrolysis; pentose-rich media; Debaryomyces hansenii

Document Type: Research article

DOI: http://dx.doi.org/10.1385/ABAB:115:1-3:1059

Affiliations: 1: Departmento de Biotecnologia, INETI, Estrada do Paço do Lumiar 22, 1649-038, Lisboa, Portugal, 2: Departmento de Biotecnologia, INETI, Estrada do Paço do Lumiar 22, 1649-038, Lisboa, Portugal, Email: francisco.girio@ineti.pt

Publication date: 2004-03-01

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• In this Subject: Anatomy & Physiology ,  Biotechnology ,  Organic Chemistry ,  Biochemistry
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