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Caetano M.S.,Federal University of Lavras | Ramalho T.C.,Federal University of Lavras | Vieira T.G.,Unilavras Centro Universitario Of Lavras | Goncalves A.D.S.,Federal Institute of Education Science and Technology | And 2 more authors.
Journal of Chemistry | Year: 2013

Structure and stability of [ (N a) n (P h e) m ] n + clusters in the ground state were analyzed at the theoretical and experimental levels. Our experimental and theoretical findings showed that the [ (N a) n (P h e) m ] n + clusters in gas phase tend to form mainly planar rings of four members. The symmetry and the small dipole moment in these specific configurations suggested that their stability could be associated with an alignment of the water molecules, maximizing attractive electrostatic interactions caused by changes in the charge distribution of the clusters. © 2013 Melissa S. Caetano et al.

Campos C.R.,Federal University of Lavras | Silva C.F.,Federal University of Lavras | Dias D.R.,Unilavras Centro Universitario Of Lavras | Basso L.C.,Escola Superior de Agricultura Luiz de Queiroz | And 2 more authors.
Journal of Applied Microbiology | Year: 2010

Aims: To evaluate the dominance and persistence of strains of Saccharomyces cerevisiae during the process of sugar cane fermentation for the production of cachaça and to analyse the microbial compounds produced in each fermentative process. Methods and Results: Three S. cerevisiae strains were evaluated during seven consecutive 24-h fermentation batches using recycled inocula. The UFLA CA 116 strain had the largest population of viable organisms, and the maximum population was achieved in the fourth batch after 96 h of fermentation. The UFLA CA 1162 and UFLA CA 1183 strains grew more slowly, and the maximum population was reached in the seventh batch. Molecular characterization of isolated yeast cells using PFGE (pulse field gel electrophoresis) revealed that more than 86% of the isolates corresponded to the initially inoculated yeast strain. The concentration of aldehydes, esters, methanol, alcohol and volatile acids in the final-aged beverages were within the legal limits. Conclusions: Cachaça produced by select yeast strains exhibits analytical differences. UFLA CA 1162 and UFLA CA 116 S. cerevisiae isolates can be considered the ideal strains for the artisanal production of cachaça in Brazil. Significance and Impact of the Study: The use of select yeast strains can improve the quality and productivity of cachaça production. Our findings are important for the appropriate monitoring of yeast during sugar cane fermentation. In addition, we demonstrate that UFLA CA 116 and UFLA CA 1162, the ideal yeast strains for cachaça production, are maintained at a high population density. The persistence of these yeast strains in the fermentation of sugar cane juice promotes environmental conditions that prevent or decrease bacterial contamination. Thus, the use of select yeast strains for the production of cachaça is a viable economic alternative to standardize the production of this beverage. © 2009 The Society for Applied Microbiology.

Deuner S.,Federal University of Pelotas | Alves J.D.,Federal University of Lavras | Zanandrea I.,Embrapa Clima Temperado | de Fatima Pereira Goulart P.,Unilavras Centro Universitario Of Lavras | And 3 more authors.
Scientia Agricola | Year: 2011

Coffee (Coffea arabica) plants show a positive relationship between stomatal closure and formation and accumulation of H 2O 2. However, for coffee plants under water restriction such relationship has never been studied. The objective of the present study was evaluate the stomatal movement and the antioxidant capacity of coffee seedlings under different water regimes. Eight months old coffee seedlings of cv. Catuaí IAC 99 were submitted to field capacity, gradual and total suspension of irrigation during a period of 21 days. Evaluations of leaf water potential (Ψ w) were performed in the beginning of the morning, and stomatal resistance, transpiration rate and vapor pressure deficit were determined at 10 am and 5 pm. All biochemical and enzymatic determinations were performed in leaves collected at 5 pm. Evaluations and samplings were performed at three days intervals. There was no variation in Ψ w during the evaluated period for plants in field capacity. However, an expressive decrease of Ψ w following day 12, reaching values near -2.5 MPa at the end of the experiment was observed for plants submitted to gradual suspension of irrigation. For plants submitted to total suspension of irrigation, Ψ w decreases after the sixth day, reaching -2.5 MPa at day 15. The decay of Ψ w in plants submitted to gradual and total suspension of irrigation reflected in increased stomatal resistance and in a decreased transpiration rate leading to an increase in hydrogen peroxide formation and, on final stages, increase in lipid peroxidation. As a conclusion, an increase in the activity of antioxidant enzymes as well as in the levels of ascorbate and dehydroascorbate was observed, which act in the detoxification of free radicals formed as result of the water stress.

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