Nanocompósitos com atividade antioxidante de amido de milho/isolado proteico de soro de leite/ óleo essencial de alecrim obtidos por extrusão termoplástica

In order to improve the quality and safety of food, the active packaging emerges as a new technology based on the release of composites beneficial to food products. Thus, biodegradable films incorporated with active substances have the function of acting as a barrier to external elements, protecting the product and increasing its shelf life. They are formulated from proteins, polysaccharides, lipids or from the combination of these compounds. However, there is a need to improve the performance properties of these packages. Nanotechnologies, then, emerges with the study of many nanoparticles as additives to modify the performance of biodegradable polymers. With this, we aimed at developing and active antioxidant film of corn starch blenders and whey protein isolate with rosemary essential oil or microcapsules of rosemary essential oil reinforced with sodium montmorillonite (MMTNa + ) nanoparticles by extrusion. The films were developed and characterized in a first stage for the selection of the best polymeric blender using the following analyses: water vapor permeability (WVP), machanical properties; optical, thermogravimetry (TG), differential scanning calorimetry (DSC), x-ray diffraction (XRD) and scanning electron microscopy (SEM). In the second stage, montmorillonite clay nanoparticles and rosemary essential oil were added as reinforcement to evaluate its antioxidant effect. In a third stage, we studied the addition of microcapsules of rosemary essential oil (MR) as a form of protecting the active agent and its antioxidant potential in the films. The results indicate that the development of p olymeric blender with 30% of corn starch substitution is the most indicated for future work. The addition of rosemary essential oil or microcapsule of rosemary essential oil allowed for the obtaining of nanocomposites with antioxidant potential for application in food packages.

Four year multitrophic food web: source food web description, methodology accuracy and species diversity

Food webs have been used in order to understand the trophic relationship among organisms within an ecosystem, however the extension by which sampling efficiency could affect food web responses remain poorly understood. Still, there is a lack of long-term sampling data for many insect groups, mainly related to the interactions between herbivores and their host plants. In the first chapter, I describe a source food web based on the Senegalia tenuifolia plant by identifying the associated insect species and the interactions among them and with this host plant. Furthermore, I check for the data robustness from each trophic level and propose a cost-efficiently methodology. The results from this chapter show that the collected dataset and the methodology presented are a good tool for sample most insect richness of a source food web. In total the food web comprises 27 species belonging to four trophic levels. In the second chapter, I demonstrate the temporal variation in the species richness and abundance from each trophic level, as well as the relationship among distinct trophic levels. Moreover, I investigate the diversity patterns of the second and third trophic level by assessing the contribution of alfa and beta-diversity components along the years. This chapter shows that in our system the parasitoid abundance is regulated by the herbivore abundances. Besides, the species richness and abundances of the trophic levels vary temporally. It also shows that alfa-diversity was the diversity component that most contribute to the herbivore species diversity (2nd trophic level), while the contribution of alfa- and beta-diversity changed along the years for parasitoid diversity (3rd level). Overall, this dissertation describes a source food web and bring insights into some food web challenges related to the sampling effort to gather enough species from all trophic levels. It also discuss the relation among communities associated with distinct trophic levels and their temporal variation and diversity patterns. Finally, this dissertation contributes for the world food web database and in understanding the interactions among its trophic levels and each trophic level pattern along time and space