Feruloyl Esterase Activity from Coffee Pulp in Solid-State Fermentation
Gladys G. Pérez-Morales1, Ascención Ramírez-Coronel1, Oswaldo Guzmán-López1, Francisco Cruz-Sosa1, Isabelle Perraud-Gaime2, Sevastianos Roussos2 and Gerardo Saucedo-Castañeda1*
1Department of Biotechnology, Metropolitan Autonomous University, Av. San Rafael Atlixco No. 186, Col. Vicentina, CP 09340 Iztapalapa, Mexico, D.F., Mexico
2Department of Microbial Ecology and Biotechnology, Paul Cezanne University, FST, Av. Escadrille Normandie Niémen, FR-13397 Marseille Cedex 20, France
Article history:
Received September 18, 2010
Accepted January 27, 2011
Key words:
coffee pulp, feruloyl esterase, hydroxycinnamic acids, solid-state fermentation, solvent extractions
Summary:
Hydroxycinnamic acids (HAs) have a potential application in the food and pharmaceutical industry because they are rich in phenolics. Feruloyl esterases release phenolic compounds from plant cell walls. Coffee pulp is rich in HAs linked to polysaccharides. A solvent extraction of free HAs was performed with aqueous methanol (80 %). A response surface methodology was applied to optimise the extraction of these compounds from coffee pulp, and the best results were obtained at 56 °C for 34 min. Alkaline and acid hydrolyses were performed to evaluate the content of linked HAs. Treated (extracted) coffee pulp was used to produce feruloyl esterases in solid-state fermentation by Aspergillus tamarii V12307, previously selected by a hydrolysis plate assay. Different dilutions of a culture medium were added to the coffee pulp, and the diluted medium with half the nutrients allowed for higher CO2 production. A specific growth rate (μCO2 ) of 0.25 h–1 and a lag phase (tlag) of 14.3 h were observed under the selected conditions. Finally, enzymatic activities were 14.0 and 10.8 nkat per g of dried matter when methyl and ethyl ferulate were used as substrates, respectively. Productivities (9.3 and 7.2 nkat per g of dried matter per day, respectively) were higher when compared to other studies carried out in solid-state fermentation. Utilisation of coffee pulp for enzyme production improves the added value of this abundant by-product of the coffee industry.
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