RESUMO

Background: Strawberry is a fruit with a high antioxidant capacity due to its richness in phenolic compounds that suffer a rapid post-harvest deterioration. Spray drying is an alternative to reduce losses; however, these powders present problems of instantanisation, making it necessary to implement agglomeration processes. During storage, powdered food products can undergo a series of changes in their amorphous state from a product initially in a vitreous state to a gummy state, where all properties are substantially modified due to the increased mobility of water in the matrix. Methods: The research objective was to evaluate the storage stability (6 months) of a fluidized bed agglomerated strawberry powder mixture at three temperatures (15, 25 and 25°C), a controlled environment at 65% relative moisture, and PET foil laminated film bags as packaging. Moisture, water activity, bulk and compacted density, Carr and Hausner indices, solubility, hygroscopicity, wettability, angle of repose, antioxidant capacities, total phenols, anthocyanins, vitamin C, color (CIE-Lab) and particle size were monitored. Results: ANOVA showed statistically significant differences (p<0.05) for all dependent variables concerning storage time; storage temperature had no significant effect on S, ABTS, DPPH and Hu. The time-temperature interaction during storage had no significant effect (p>0.05) on S, ABTS, DPPH, Hu and L. The agglomerate showed moisture and aw values that confer excellent stability against deterioration reactions; it retained good fluidity, low cohesiveness, and retentions above 50% for antioxidant capacity, 76% for total phenols, 39% for anthocyanins, and 40% for vitamin C; particle size was retained during the evaluation. The color was only affected in the 35°C treatment from the fifth month onwards. Conclusions: The study will serve as a tool for the determination of the shelf life of the chipboard once the critical values of the attributes selected as predictors of shelf life are defined.

Assuntos

RESUMO

Clustering of species with similar niches or traits occurs in communities, but the mechanisms behind this pattern are still unclear. In the emergent neutrality model, species with similar niches and competitive ability self-organise into clusters. In the hidden-niche model, unaccounted-for niche differences stabilise coexistence within clusters. Finally, clustering may occur through alliances of species that facilitate each other. We tested these hypotheses using population-growth models that consider interspecific interactions parameterised for 35 species using field data. We simulated the expected community dynamics under different species-interaction scenarios. Interspecific competition was weaker within rather than between clusters, suggesting that differences in unmeasured niche axes stabilise coexistence within clusters. Direct facilitation did not drive clustering. In contrast, indirect facilitation seemingly promoted species alliances in clusters whose members suppressed common competitors in other clusters. Such alliances have been overlooked in the literature on clustering, but may arise easily when within cluster competition is weak.

Assuntos

RESUMO

Negative density dependence (NDD) of recruitment is pervasive in tropical tree species. We tested the hypotheses that seed dispersal is NDD, due to intraspecific competition for dispersers, and that this contributes to NDD of recruitment. We compared dispersal in the palm Attalea butyracea across a wide range of population density on Barro Colorado Island in Panama and assessed its consequences for seed distributions. We found that frugivore visitation, seed removal and dispersal distance all declined with population density of A. butyracea, demonstrating NDD of seed dispersal due to competition for dispersers. Furthermore, as population density increased, the distances of seeds from the nearest adult decreased, conspecific seed crowding increased and seedling recruitment success decreased, all patterns expected under poorer dispersal. Unexpectedly, however, our analyses showed that NDD of dispersal did not contribute substantially to these changes in the quality of the seed distribution; patterns with population density were dominated by effects due solely to increasing adult and seed density.

Assuntos

RESUMO

Os estafilococos coagulase negativos (ECNs) são cocos Gram-positivos usualmente considerados contaminantes em laboratórios de microbiologia clínica. Apesar de pertencer a este grupo, Staphylococcus lugdunensis pode causar infecções complicadas, como endocardites, infecções de pele e tecidos moles, osteomielites, entre outras. Além da formação de biofilmes, apresenta patogenicidade similar ao Staphylococcus aureus. É um dos principais agentes causadores de endocardites, com taxa de mortalidade de até 70 por cento. Pode ser confundido com S. aureus quando se utilizam testes rápidos para sua identificação, como a pesquisa de clumping factor, no caso de teste de coagulase em lâmina, ou em testes de aglutinação direta em látex. Pode ser facilmente identificado por meio de provas bioquímicas acessíveis, como a presença de atividade da ornitina descarboxilase e pirrolidonil arilamidase (PYR). Apresenta sensibilidade à maioria dos agentes antimicrobianos, devendo ser pesquisada rotineiramente a presença de betalactamases e do gene mecA por meio de testes com cefalosporina cromogênica e suscetibilidade à cefoxitina, respectivamente. Convém salientar que os critérios interpretativos utilizados para avaliar a sensibilidade à cefoxitina são os mesmos preconizados para S. aureus e diferentes dos utilizados para os outros ECNs. Apesar de incomum, o S. lugdunensis é um patógeno com acentuada virulência que deve ser corretamente identificado, pois raramente poderá ser considerado contaminante quando isolado de sítios estéreis.

Coagulase-negatives staphylococci (CNS) are Gram-positives cocci commonly regarded as contaminants in clinical microbiology laboratories. Despite belonging to this group, Staphylococcus lugdunensis may cause complicated infections such as endocarditis, skin infections and soft tissue, osteomyelitis, among others. Apart from the formation of biofilms, it has pathogenic features similar to Staphylococcus aureus. It may be mistakenly identified as S. aureus when using rapid identification tests, such as clumping factor in slide coagulase or in agglutination latex tests. It is easily identified through available biochemical tests, such as the presence of ornithine decarboxylase and pyrrolidonyl arylamidase (PYR). It presents sensitivity to most antimicrobial agents. Furthermore, the presence of beta-lactamase and mecA gene should be routinely investigated by testing with chromogenic cephalosporin and cefoxitin susceptibility, respectively. It is convenient to highlight that the interpretative criteria used to evaluate cefoxitin sensitivity are the same recommended for S. aureus and different from those used for other CNS. Despite the fact it is atypical, S. lugdunensis is a virulent pathogen, which must be accurately identified insofar as it will rarely be deemed as a contaminant when isolated from sterile sites.