Natural rubber is an essential material, especially for plane and truck tyres but also for medical gloves. Asia ranks first in the production of natural rubber, of which the Hevea tree is currently the sole source. However, it is anticipated that this source alone will not be able to fulfill the growing demand. Guayule, a shrub native to northern Mexico and southern United States, may also contribute. This plant not only contains polyisoprene, but also resin, a mixture of lipids and terpenoids. This review summarizes various aspects of this plant, from the usage history, botanical description, geographical distribution and cultivation practices, down to polyisoprene and resin biosynthesis including their distribution within the plant and molecular composition. Finally, the main processes yielding dry rubber or latex are depicted, as well as the properties of the various extracts along with economic considerations. The aim is to provide a wide picture of current knowledge available about this promising crop, a good feedstock candidate for a multiple-product biorefinery.
Objetivo: evaluar el efecto de cuatro niveles de alimentación simulados in vitro sobre la producción de metano in vitro.
Diseño/metodología/aproximación: Los niveles de alimentación simulados in vitro fueron; 5.7 kg MS, 11.9 kg MS, 19.5 kg MS y 21.8 kg MS ya que estos niveles de alimentación pueden presentarse in vivo en diferentes explotaciones ganaderas del mundo. Se utilizó la técnica de producción de gas in vitro para incubar muestras de pasto nativo dominado por Penisetum clandestinum (80%) y malezas (20%) en cuatro niveles; MS0.57, MS1.19, MS1.95, MS2.18 a las 12, 24, 48 y 72 h.
Resultados: se encontraron diferencias significativas (p<0.05) entre los diferentes niveles de MS a las 12 h, siendo diferentes MS0.57 y MS1.19 de MS1.95, MS2.18. A las 24 horas MS0.57 presentó la menor concentración y fue diferente significativamente (P<0.05) de los otros niveles de MS. A las 48 y 72 h MS1.19 fue significativamente diferente (P<0.05) al resto de los niveles evaluados ya que presentó la menor concentración de CH4 mientras que MS0.57 a las 72 h, presentó la mayor concentración de CH4.
Limitaciones del estudio/implicaciones: los resultados de este trabajo fueron obtenidos a partir de un estudio in vitro; por lo tanto, no son aplicables directamente a las emisiones entéricas in vivo, no obstante, se tiene una aproximación de cuanta energía metabolizable se puede perder en forma de metano.
Hallazgos/conclusiones: se observó un efecto lineal de los cuatro niveles de alimentación simulados in vitro sobre la producción acumulada de metano a las 12 h posterior a la incubación. Los niveles MS0.57 y MS1.19 presentaron la menor producción de metano a las 24 y 48 h, respectivamente.
Guayule (Parthenium argentatum Gray) is a semi-arid shrub, native from the Chihuahan desert. This plant produces polyisoprene and resin. Polyisoprene is the main focal point of many researches, from structure to properties. Today, some processes are used to extract polyisoprene under its dry form, using solvent extraction, to produce rubber (used in truck or airplane tires) or as an emulsion, to make latex products by dipping (used in medical gloves, condoms, etc.). This article focuses on guayule resin which has some interesting applications in adhesives, coatings, pharmaceuticals, etc. In order to better know the resin composition and to be able to perform comparisons between varieties or seasons, liquid and gas chromatographic analysis methods have been described, for the groups of molecules composing the resin (polyphenols, guayulins, free fatty acids, di and triacylglycerols, argentatins, alkanes, alkanals, sugars, organic acids). Unlike other articles, this study aims to analyze all components of the same resin; the average composition of a guayule resin is given.
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