The heterogeneity of color distribution between sapwood and heartwood limits the market for wood from fast-growth plantations of tropical species. Wood color is associated with wood extractives contents. This study presents the relationship between wood color parameters measured by the CIELab color system and total amount of extractives and phenolic-type extractives in ethanol-toluene and hot water extracts of wood from two fast-growth plantation species. The results demonstrated that the difference in sapwood and hardwood color in Vochysia guatemalensis and Acacia mangium is caused by lower concentrations of extractives in sapwood of both species. Additionally, variations in total extractive and phenolic content have different effects on the color parameters (L*, a* and b*) of both species studied. In Vochysia guatemalensis wood, parameter L* decreases as total extractive and phenolic content increases; however, parameter a* increases as the content of extractives and phenols increases. In Acacia mangium, the amount of phenols showed no relationship with the color parameters. The ethanol-toluene total extractive content, however, shows a relationship with several color parameters. An increase in the content of total extractives in water and ethanol-toluene increases parameter a*, but decreases parameter L*.

Butanol is a precursor of many industrial chemicals, and a fuel that is more energetic, safer and easier to handle than ethanol. Fermentative biobutanol can be produced using renewable carbon sources such as agro-industrial residues and lignocellulosic biomass. Solventogenic clostridia are known as the most preeminent biobutanol producers. However, until now, solvent production through the fermentative routes is still not economically competitive compared to the petrochemical approaches, because the butanol is toxic to their own producer bacteria, and thus, the production capability is limited by the butanol tolerance of producing cells. In order to relieve butanol toxicity to the cells and improve the butanol production, many recovery strategies (either in situ or downstream of the fermentation) have been attempted by many researchers and varied success has been achieved. In this article, we summarize in situ recovery techniques that have been applied to butanol production through Clostridium fermentation, including liquid–liquid extraction, perstraction, reactive extraction, adsorption, pervaporation, vacuum fermentation, flash fermentation and gas stripping. We offer a prospective and an opinion about the past, present and the future of these techniques, such as the application of advanced membrane technology and use of recent extractants, including polymer solutions and ionic liquids, as well as the application of these techniques to assist the in situ synthesis of butanol derivatives.

Secondary metabolites from Hibiscus sabdariffa have been used to prevent different diseases. Roselle Hibiscus is known for being rich in phenolic bioactive compounds. The extraction conditions are directly related to the chemical composition and then to the overall bioactivity of the extract. In this study, a Box-Behnken experimental design has been used to optimize the antioxidant activity, considering four variables: ethanol:water ratio, temperature, extraction time, and solvent:solid ratio. The experiment comprises 27 experiments and 3 repetitions at the central point. The results are described by surface response analysis and a second-degree polynomial equation. The model explains 87% of the variation in the response. The maximum antioxidant activity is yielded when 1% solids are extracted in 35.5% ethanol at 60 °C for 33 min. Finally, a nutritional functional supplement of 495 µmol Trolox Equivalent (TE) antioxidant capacity was prepared with the optimized extract.

La naturaleza química de los taninos condensados los convierte en una fuente natural de compuestos orgáni- cos, con una aplicación potencialmente amplia para usos medicinales e industriales. La extracción y análisis de este tipo de metabolitos a partir de la flora de diversas regiones del planeta ha sido el objetivo del estudio de diversos grupos de trabajo, y en este caso se ha querido hacer un aporte al estado del conocimiento actual, realizando un estudio sobre la natu- raleza y la cantidad del tanino condensado que se puede extraer de la corteza de 11 especies arbóreas presentes en Costa Rica: guanacaste (Enterolobium cyclocarpum), alcornoque (Licania arborea), jobo (Spondias mom- bin), pochote (Pachira quinata), níspero (Manilkara chicle), almendro (Andira inermis), roble (Tabebuia rosea), cedro (Cedrela odorata), cenízaro (Samanea saman), pino (Pinus caribaea) y ciprés (Cupressus lusitanica). Las muestras de corteza fueron preparadas, secadas y extraídas con etanol. Se analizaron los extractos etanóli- cos para determinar el contenido de taninos condensa- dos a través del número de Stiasny, y se caracterizaron mediante espectroscopía infrarroja (FT-IR). Las especies con mayor proporción de material extraído fueron guanacaste (9.5841% m/m), pochote (15.0066% m/m), pino (19.3400% m/m) y ciprés (10.5300% m/m), mientras que los extractos con una mayor proporción de taninos condensados correspondieron a alcornoque (61.9% m/m), jobo (66.1% m/m), pochote (72.8% m/m), níspero (50.5% m/m), cedro (72.7% m/m) y pino (70.7% m/m).