Francisco Klebson Gomes dos Santos

Incorporation of bentonite clay in cassava starch films for the reduction of water vapor permeability

Complete factorial planning 23 was applied to identify the influence of the cassava starch(A), glycerol(B) and modified clay(C) content on the water vapor permeability(WVP) of the cassava starch films with the addition of bentonite clay as a filler, its surface was modified by ion exchange from cetyltrimethyl ammonium bromide. The films were characterized by X-ray diffraction(XRD), fourier transform by infrared radiation(FTIR), atomic force microscopy(AFM) and scanning electron microscopy(SEM). The factorial analysis suggested a mathematical model thats predicting the optimal condition of the minimization of WVP. The influence of each individual factor and interaction in the WVP was investigated by Pareto graph, response surface and the optimization was established by the desirability function. The sequence of the degree of statistical significance of the investigated effects on the WVP observed in the Pareto graph was C>B>A>BC>AC. Interactions AB, BC and AC showed that the modified clay was the factor of greater significance.

Use of biopolymeric coating hydrophobized with beeswax in post-harvest conservation of guavas

Biopolymeric coatings are effective in maintaining the chemical and sensory characteristics of fruits and vegetables because they preserve innumerable nutrients effectively for long periods of storage. Coatings based on cornstarch (3%), cassava starch (2%) and gelatin (5%) were synthesized. Beeswax (BW) was added as a hydrophobic agent in the polymeric network at different concentrations relative to the dry base of biopolymer. The biofilm containing 10% BW presented the best results in the water vapor transmission rate (WVTR) and the effect of the BW incorporation was also evaluated from surface roughness and SEM. An 80% increase in elasticity and 15% decrease in solubility indicated resistance against unfavorable environmental conditions. Physical-chemical analysis showed that its use minimized weight loss, guaranteeing adequate ripening of the fruits during 15 days in a regulated environment: 15 °C ± 2 °C, 90% ±2% RH. The sensorial attributes indicated better acceptability of these fruits, demonstrating the potential of this coating.

Rheological and some physicochemical characteristics of selected floral honeys from plants of caatinga

The aim of this paper was to investigate the physicochemical characteristics and rheological behavior of some floral honeys from species of wild plants found in the Caatinga biome, as well as, correlate honey viscosities with its chemical composition. Thus, five honeys with floral predominance of typical plants foraged by honeybees in Caatinga were analyzed. Results showed that moisture content of honeys ranged from 17.45 to 21.50 g/100g. The samples exhibited higher fructose content (37.58 - 43.95 g/100g) and lower glucose content (27.41- 33.80 g/100g). The glucose-water ratio ranged from 1.55 to 1.80. Sucrose contents, excluding Croton campestris honey sample, exhibited values above the highest sucrose content (6.0 g/100g) allowed by Brazilian norm. The ash content ranged from 0.02 to 0.19 %. The insoluble solids content were above 0.1 g/100 g. The electrical conductivity ranged between 144.90 and 412.55 µS.cm-1. All the honey samples behaved as Newtonian fluids. The viscosity values, measured at 293 K, varied from 1.90 to 8.55 Pa.s. An empirical mathematical model adapted from the Arrhenius model provides a good description of honey viscosity as a function of combined effects of temperature and moisture content.

Structural, Morphological and Textural Features of EDTA-Citrate-Synthesized BaPrO3 Perovskite-Type Oxide

BaCeO3 has attracted great interest in research worldwide, whether doped with other elements on the site A and / or B of perovskite ABO3 or not, thus enabling its use in different applications. However, the properties exhibited by perovskite depend on partial or total replacement at the site, as well as the applied synthesis method. In this work we studied crystal structure, crystallographic parameters, morphology and textural properties of BaPrO3 perovskite synthesized by EDTA-Citrate complexation process. The adopted methodology makes it possible to obtain powders with orthorhombic crystal structure ( a=6.07 Å; b=6.3 Å e c=8.7 Å) and crystallite size of approximately 100 nm. That perovskite has dense and irregular agglomerates with surface area and pore volume of about 2.37 m2 g-1 and 0.7x10-8m3g-1, respectively. Finally, the methodology has demonstrated effectiveness in achieving crystalline phase with similar characteristics and properties obtained by different methods.

Desenvolvimento de um kit de reator de leito fixo de bagaço de cana-de-açúcar para uso didático

E de fundamental importância o desenvolvimento de praticas de laboratorio nos cursos de engenharia, porem os altos custos dos kits didaticos muitas vezes inviabilizam sua aquisicao. No entanto, o presente trabalho teve como objetivo desenvolver um kit para aulas de cinetica e reatores, utilizando materiais de facil aquisicao e com carater ambiental, uma vez que o leito fixo e composto por bagaco de cana-de-acucar. Para estudar a cinetica, variou-se o volume de alcool etilico alimentado e a altura de leito fixo no reator, observando o comportamento do rendimento e da produtividade. Avaliou-se a influencia da adicao do alcool etilico e acido acetico na producao deste e avaliou-se a atividade operacional do recheio atraves do reuso do mesmo. A acidez do produto aumentou com o passar do tempo e apos cerca de 12 horas manteve-se constante. O rendimento teve um aumento proporcional a diminuicao do volume de alimentacao e ao aumento da altura do leito fixo. Aplicando os valores obtidos em modelos de cinetica de primeira e segunda ordem, concluiu-se que o modelo cinetico de primeira ordem se ajustou melhor aos dados obtidos.