Integral valorization of brewer´s spent grain by emerging technologies

Abstract

En un contexto de economía circular, una completa valorización de residuos procedentes de la industria agroalimentaria para convertirlos en productos de alto valor añadido, minimiza los impactos ambientales y maximiza el uso de recursos renovables. En este sentido, se propone la valorización integral del bagazo de cerveza (BSG), el principal subproducto de la industria cervecera (85%), empleando tecnologías emergentes respetuosas con el medio ambiente. Esta Tesis Doctoral propone el uso de diferentes tecnologías verdes y eficientes para la recuperación de los compuestos bioactivos del BSG, tales como la extracción con fluidos supercríticos y la extracción asistida por ultrasonidos (UAE). Además, se ha propuesto el uso de agua subcrítica (subW) para hidrolizar y fraccionar los componentes estructurales del BSG (fracciones de lignocelulosa y proteínas), recuperando al mismo tiempo diferentes compuestos bioactivos, tales como compuestos fenólicos, biopéptidos y aminoácidos, dentro de un concepto de biorrefinería integrada.

The development of new strategies in the bioeconomy field aims to find alternatives to fossil-based feedstocks for the production of fuels and chemicals, since the availability of fossil resources is limited, and their use is associated with the global climate change. Furthermore, waste generation is increasing exponentially, as consequence of the growing population and higher quality of life. One of the most attractive alternatives to deal with both problems is the development of sustainable biorefineries for processing biomass into different products and energy, being key in the context of circular economy, closing loops of streams, and valorizing multiple outputs, considering both, environmental and economic aspects. In this sense, the integral conversion of lignocellulosic agro-industrial residual biomass (second-generation biomass) into high value-added products minimizes environmental impacts and maximizes the use of renewable resources. In this work, an integral valorization of brewer´s spent grain (BSG) by using clean and environmentally friendly technologies has been proposed. BSG is the main byproduct of the brewing industry (85%). It is a lignocellulosic biomass with high protein content (10 - 30%, w/w) and around 6% of lipids, being also a valuable source of phenolic compoundsthat have demonstrated antioxidant effects. Based on its chemical composition, the integration of BSG within a biorefinery concept is of great interest to obtain different high-value biocompounds. However, due to the recalcitrant structure of lignocellulosic biomass, the fractionation of these byproducts into their individual building blocks remains a challenge for the optimal development of second-generation biorefineries.