Abstract Recently, the development of biofuels from renewable sources and the use of friendly environmental technologies have received a great deal of worldwide interest. Thus, many changes in the energy production model and management are necessary. The use of forest residues as raw material for bioenergy generation is an interesting option since the biofuels obtained are less polluting than fossil fuels. In addition, while heat and electricity can be obtained by other renewable alternatives (wind, solar and hydro), the production of liquid fuels and chemicals requires biomass transformation. The selection of the conversion process depends on the type, property and biomass stock, the desired form of the bioenergy, environmental standards and economic conditions. The aim of this work is to describe the different processes through which energy can be obtained, as well as the potential use of forest residues as raw material to produce the different types of bioenergy and, to describe the different biofuels that can be obtained by these processes. In addition, we analyze current challenges and unsolved problems in bioenergy production such as waste collection, scale-up and techno-economic feasibility.

Resumen Una de las prioridades del mundo actual es la generación de bioenergéticos sustentables y amigables con el medio ambiente, para lo cual son necesarios cambios en los modelos de producción y utilización de energía. El uso de residuos forestales como una fuente de biomasa para la generación de bioenergéticos representa una alternativa potencial, ya que genera un biocombustible menos contaminante en comparación con los de origen fósil. Además, mientras que el calor y la electricidad pueden ser generados por otras alternativas renovables como viento, sol y agua, la producción de combustibles y la síntesis de productos químicos requieren transformar la biomasa. La elección de la estrategia de conversión depende del tipo, propiedades y cantidad de la biomasa disponible, de los requerimientos de uso, así como de los estándares ambientales y condiciones económicas. El objetivo del presente trabajo es describir los diferentes procesos a través de los cuales se puede obtener energía a partir de residuos de biomasa forestal, así como el potencial que tienen estos residuos en la producción de los diferentes tipos de bioenergéticos. Asimismo, se describen los desafíos y problemas que aún siguen sin resolver, como lo son la recolección de residuos, escalamiento y costos de producción.

The potential of lipases (E.C.3.1.1.3.) as biocatalysts for the production of fatty acid derivatives for the food and nutraceutical industries, such as flavouring esters, fatty acid esters of antioxidants and structured lipids, is enormous, mainly due to their high regio- and stereo-selectivities, in addition to the other well-known advantages of enzymatic processes. The replacement of chemical catalysts by lipases presents great benefits in terms of the nutritional properties of the obtained products and environmental care. The reactions performed for the production of these compounds, as well as the best operation conditions, the biocatalysts used, reactor types and operation mode, are addressed in this review.

Recentemente, existe um crescente interesse na atividade antioxidante e na capacidade de melhora da saúde da palma forrageira. A capacidade antioxidante das polpas dos frutos da palma forrageira foi avaliada anteriormente. Neste trabalho, compostos fenólicos, flavonoides e taninos da casca e sementes de quatro cultivares da palma forrageira foram examinados, assim como a sua capacidade antioxidante. Os taninos foram os principais compostos fenólicos nas sementes da palma forrageira, representando quase 50% de todos os cultivares. A análise de variância revelou que a maturação, o cultivar e sua interação tiveram um efeito altamente significativo sobre o conteúdo dos fenóis totais, taninos e flavonoides da pele da palma forrageira. Em sementes, apenas o estágio de maturação e a interação (estágio de maturação x cultivar) foram significativos em fenólicos totais e taninos. O teor de flavonoides de sementes não foi afetado por nenhum dos fatores ou suas interações. A capacidade antioxidante foi maior na pele do que nas sementes. Geralmente, as frutas com casca verde-clara ou amarelo-marrom apresentam maior atividade antirradical e maior valor de capacidade antioxidante equivalente a Trolox (TEAC), quando comparadas com os frutos vermelho-púrpura. De fato, os subprodutos da palma forrageira podem ser explorados como uma fonte boa e barata de antioxidantes naturais.

Recently, an increased interest in antioxidant activity and health-improving capacity of cactus pear has been registered. The antioxidant capacity of the pulp of cactus-pear fruits has been previously assessed. In this work, total phenolics, flavonoids and tannins of peel and seeds of four cactus pear cultivars were examined as well as their antioxidant capacity. Tannins were the major phenolics in cactus pear seeds accounting for almost fifty percent for all cultivars. Analysis of variance revealed that ripeness, cultivar, and its interaction had highly significant effect on the total phenolics, tannin, and flavonoid contents of cactus pear peel. With regard to the seeds, only the stage of ripeness and interaction (ripeness stage x cultivar) were significant on total phenolics and tannins contents. The flavonoid content in seeds was not affected by any of the factors or their interactions. The antioxidant capacity was higher in the peel than in the seeds. Generally, fruits with light-green or yellow-brown peel have higher antiradical activity and Trolox equivalent antioxidant capacity (TEAC) values compared with those with red-purple peel. Cactus pear by-products can indeed be exploited as a good and cheap source of natural antioxidants.