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Anápolis, Brazil

The objective of this work was to study the water adsorption of raw and pregelatinized rice flours of selected rice cultivars BRS Primavera and BRS Monarca. Pregelatinized samples were obtained from rice grains cooked in water for 10 to 40 minutes. The obtained flours were analyzed for water content, total reducing sugars and adsorption isotherms. The isotherms were obtained at different water activities (0.112 to 0.972) at 30°C. From the mathematical models of water adsorption (Halsey, Oswin and GAB), GAB equation was the model that best explained the variation of isotherms as a function of water activity (maximum at 0.75) as being the safest for rice products storage. Within water activity between 0 and 0.3, the structure of starch granules of the raw flours resists to water adsorption. The results suggest that the raw rice flour of BRS Monarca is less hygroscopic than BRS Primavera and may have longer shelf life when stored in a similar condition to its monomolecular layer. When cooking at longer time, the grains of rice flour BRS Primavera were more stable because they are less hygroscopic than their counterparts of BRS Monarca. Source


The present work aimed at using the Mangarito rhizomes starch for use as coatings for post-harvest fruit jabuticaba. The quality of coverage was assessed by the permeability and solubility of the biodegradable films and also by physical and chemical parameters of fruits determined due to certain storage time. The biodegradable films were prepared from Mangarito rhizomes starch and glycerol in concentrations ranging from 1.44 and 3.56 g, 12.93 and 27.70% respectively. The biodegradable coatings were prepared with 2.5% starch and glycerol concentrations ranging from 10 to 30%. Was used the central composite experimental design, type star, with five replicates at center point and four axial to check the effect of variation in starch and plasticizer on the solubility and permeability of the films, aiming at selecting the best coverage by response surface methodology. For post-harvest conservation was adopted a completely randomized design arranged in a 4×5 factorial scheme, with five replicates, the first factor corresponded to the treatments: 0 to 30% glycerol and the second to storage time (0-4 days). The increase in glycerol concentration in the solution filmogenic collaborated with the increased permeability and solubility of the films. The biodegradable coatings were not effective in controlling physical and chemical transformations of jabuticaba fruits as the loss of mass, the relationship between pH and total soluble solids and titratable acidity, not being observed significant difference between uncoated or coated fruits with different coatings. Source


Mesquita M.,University of Campinas | Bessa K.S.,UnUCET | Prado L.C.R.A.,Federal University of Goais
Engenharia Agricola | Year: 2010

The development of new irrigation equipments and the improvement of the already existent, as the microsprinkler, demand to evaluate the hydraulic characteristics as well as the appropriate installation in the field conditions to obtain higher indexes of the water distribution uniformity. This work had the objective to obtain the discharge x pressure equation, the manufacturing variation coefficient - CVf and the discharge variation coefficient - CVq, water distribution uniformity for different overlap degrees of the microsprinkler of the modulate group, orange nozzle, new and used, installed in the upside-down at 1.20 m above laboratory ground. The increase of the spacing among microsprinkler and lateral reduced the uniformity indexes for all of the pressures for the new and the used microsprinkler. The high jet concentration occurred in the range from 0.0 to 1.0 m of the support rod of the new and used microsprinkler. The wetted area by the used microsprinkler was smaller than the new one. Source


Bessa K.S.E.,UnUCET | Mesquita M.,University of Campinas | Prado L.C.R.A.,Federal University of Goais
Engenharia Agricola | Year: 2010

In the last years new models of devices were introduced for greenhouse cultivation, as the leak-preventing device and microsprinkler, it is needed to evaluate their performance. So the objective of this work was to evaluate the hydraulic performance of new and used leak-preventing device, under low and high pressure in microsprinkler of modular group and Hadar model. The CVf and CVq of the microsprinkler and the leak-preventing device of low pressure only the microsprinkler of modular group were classified as bad or unacceptable and the new high pressure as unacceptable. The leak-preventing device Hadar presented the best performance for all the performances. The leak-preventing device opened in low pressures as indicated by their manufacturers. The long time using interfered in the performance of the leak-preventing device of low pressure modular group, being the new model which presented smaller values of CVf for the opening and closing pressure. Source


Lemes M.A.,Federal University of Goais | Godinho M.S.,Federal University of Goais | Rabelo D.,Federal University of Goais | Martins F.T.,Federal University of Goais | And 4 more authors.
Acta Chimica Slovenica | Year: 2014

Powder X-ray diffraction patterns for 29 samples of magnetite, acquired using a conventional diffractometer, were used to build PLS calibration-based methods and variable selection to estimate mean crystallite size of magnetite directly from powder X-ray diffraction patterns. The best IPLS model corresponds to the Bragg reflections at 35.4° (h k l = 3 1 1), 43.0° (h k l = 4 0 0), 53.6° (h k l = 4 2 2), and 57.0° (h k l = 5 1 1) in 2θ. The best model was a GA-PLS which produced a model with RMSEP of 0.9 nm, and a correlation coefficient of 0.9976 between mean crystallite sizes calculated using Williamson-Hall approach and the ones predicted by GA-PLS method. These results indicate that magnetite mean crystallite sizes can be predicted directly from Powder X-Ray Diffraction and multivariate calibration using PLS variable selection approach. Source

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