Universidade Federal de Viçosa

About: Universidade Federal de Viçosa is a education organization based out in Viçosa, Brazil. It is known for research contribution in the topics: Population & Biology. The organization has 16012 authors who have published 26711 publications receiving 353416 citations.

Bacteriocinogenic LAB from cheeses – Application in biopreservation?

Abstract: Over the last decade, there has been an explosion of basic and applied research on lactic acid bacteria bacteriocins, because of their potential as biopreservatives and inhibition of the growth of spoilage bacteria. Although bacteriocins can be produced during cheese production, their titers are much lower than those achieved in vitro fermentations under optimal physical and chemical conditions. Safety and technological traits of the bacteriocinogenic lactic acid bacteria (LAB) have to be considered before their wide-spread applications. This review described the perspectives and hurdles to be solved in order to definitively disclose the potential of bacteriocins in the production of safe and healthy cheese commodities.

Large-scale expansion of agriculture in Amazonia may be a no-win scenario

Abstract: Using simplified climate and land-use models, we evaluated primary forests’ carbon storage and soybean and pasture productivity in the Brazilian Legal Amazon under several scenarios of deforestation and increased CO2. The four scenarios for the year 2050 that we analyzed consider (1) radiative effects of increased CO2, (2) radiative and physiological effects of increased CO2, (3) effects of land-use changes on the regional climate and (4) radiative and physiological effects of increased CO2 plus land-use climate feedbacks. Under current conditions, means for aboveground forest live biomass (AGB), soybean yield and pasture yield are 179 Mg-C ha 1 , 2.7 Mg-grains ha 1 and 16.2 Mg-dry mass ha 1 yr 1 , respectively. Our results indicate that expansion of agriculture in Amazonia may be a no-win scenario: in addition to reductions in carbon storage due to deforestation, total agriculture output may either increase much less than proportionally to the potential expansion in agricultural area, or even decrease, as a consequence of climate feedbacks from changes in land use. These climate feedbacks, usually ignored in previous studies, impose a reduction in precipitation that would lead agriculture expansion in Amazonia to become self-defeating: the more agriculture expands, the less productive it becomes.

Wet and dry tropical forests show opposite successional pathways in wood density but converge over time

Abstract: Tropical forests are converted at an alarming rate for agricultural use and pastureland, but also regrow naturally through secondary succession. For successful forest restoration, it is essential to understand the mechanisms of secondary succession. These mechanisms may vary across forest types, but analyses across broad spatial scales are lacking. Here, we analyse forest recovery using 1,403 plots that differ in age since agricultural abandonment from 50 sites across the Neotropics. We analyse changes in community composition using species-specific stem wood density (WD), which is a key trait for plant growth, survival and forest carbon storage. In wet forest, succession proceeds from low towards high community WD (acquisitive towards conservative trait values), in line with standard successional theory. However, in dry forest, succession proceeds from high towards low community WD (conservative towards acquisitive trait values), probably because high WD reflects drought tolerance in harsh early successional environments. Dry season intensity drives WD recovery by influencing the start and trajectory of succession, resulting in convergence of the community WD over time as vegetation cover builds up. These ecological insights can be used to improve species selection for reforestation. Reforestation species selected to establish a first protective canopy layer should, among other criteria, ideally have a similar WD to the early successional communities that dominate under the prevailing macroclimatic conditions.

Development and Evaluation of Active Packaging for Sliced Mozzarella Preservation

Abstract: Antimicrobial films were formed by the incorporation of nisin (NI), natamycin (NA) and a combination of both (NI + NA) into cellulose polymer. Film efficacies were evaluated in vitro against Staphylococcus aureus ATCC 6538, Listeria monocytogenes ATCC 15313, Penicillium sp. and Geotrichum sp. The films were also evaluated on sliced mozzarella cheese against moulds and yeasts, Staphylococcus sp. and psychrotrophic bacteria. Mechanical and microscopic properties of the films and the diffusion of the antimicrobial agents from the film to the cheese were also evaluated. Films containing NI showed an antimicrobial effect in vitro against S. aureus and L. monocytogenes, while films containing NA were effective in vitro against Penicillium sp. and Geotrichum sp. By the ninth day of storage at 12 ± 2°C, the count of yeasts and moulds on cheese covered with films containing NA decreased 2 log10 units compared with the count on cheese with control films. NI film did not show an effect against Staphylococcus sp., but it was effective against psychrotrophic bacteria for 6 days of storage of the cheese. The incorporation of antimicrobial compounds decreased the resistance and elongation of the films and caused changes in their molecular conformation. NI diffusion from the films to the cheese was not detected; however, time-dependent diffusion of NA from the film containing NI + NA was measured. The incorporation of NI and NA together in the films did not show an effect. The film containing NA showed potential for application as active food packaging for sliced mozzarella cheese. Copyright © 2008 John Wiley & Sons, Ltd.