Sunday, April 29, 2007

On the way to biorefinery concept: double revaluation of agrifood wastes for high added value compounds extraction and bioethanol production

Maite Zazpe1, Irantzu Alegría1, Inés del Campo1, Belén Zarranz1, Amaia Molinero1, Pedro Navarro2, Ana Romo3, and Inés Echeverría1. (1) Biomass, Renewable Energy National Centre (CENER), Ciudad de la Innovación 7. 31621, Sarriguren, Spain, (2) R+D, Centro Nacional de Tecnología y Seguridad Alimentaria, Ctra. NA-134 km. 31570, San Adrián, Spain, (3) R+D, Renewable Energy National Centre (CENER), Ctra. NA-134 km. 31570, San Adrián, Spain


A biorefinery can take advantage of different types of biomasses by producing multiple products maximizing their value. Within this framework, agrifood residues can be considered promising biomass feedstocks due to their composition, abundance, low prices and availability for high added compounds extraction and for bioethanol production.

High added value compounds such as carotene or alpha tocopherol, are found at considerable concentrations in determined agrifood residues and can be extracted by supercritical fluids technique.

Likewise, Bioethanol is considered a promising biofuel, which needs to search new alternative biomass feedstocks and therefore to reduce its production costs.

For this study agrifood wastes have been used as feedstocks for a two step revaluation. Firstly for a high value added compounds extraction and secondly, for Bioethanol production.

A characterisation of several wastes was done to identify and quantify its high-value compounds and also its composition and carbohydrate content.

Once the supercritical fluid extraction of agrifood wastes was done, the residue generated was used for bioethanol production.

For bioethanol production, firstly an autohydrolysis pretreatment was performed in order to release the sugars and make them more accessible for the following enzymatic hydrolysis and fermentation steps. Those steps were carried out using commercial available enzymes and a fermentative yeast.

The global results obtained for the bioethanol production have reached yields of around 80%. Hence, agrifood residues could be satisfactory used as feedstocks for high-value compounds extraction and for bioethanol production. However, on going assays must continue to be done for optimizing the process.

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