Carlos Alberto Gasparetto

Estudo da viscosidade aparente das polpas de manga (Keitt) e abacaxi (Pérola)

In this work, it was determined, experimentally, the rheological behavior of mango (Keitt) and pineapple (Perola) pulps, whole and centrifuged, in a Haake Rotovisco RV-20 rheometer with parallel plates PQ45, at 30° C. On the rheograms it was adjusted the Mizrahi-Berk (M-B) model, using the shear rate and shear stress. The results were presented as a ratio between the apparent viscosities (whole/centrifuged) with shear rate. This results showed the relative effect of suspended solids on the rheological behavior of each pulp.

Efeito da temperatura no comportamento reológico da polpa de manga (mangífera indica L-Keitt)

The rheological behavior of mango pulp (Keitt) was measured in the temperature range 10-60°C. Whole pulp was produced in pilot plant and finished with 1,6 mm mash sieve. Rheometry was conducted in a Haake-Rotovisco RV-20 rheometer with concentric cylinders. Temperature effect on rheological parameters of consistency was fitted to the Arrhenius model: ln(KM) = A1 + B1/T. The flow behavior index for both power law and Mizrahi-Berk were fitted as: nM = A2 + B2T.

Aplicação da metodologia de superfície de resposta para o estudo do efeito da temperatura sobre o comportamento reológico de misturas ternárias de polpa de manga e sucos de laranja e cenoura

In this work was studied the rheological behaviour of ternaries mixtures of pulp mango, orange and carrot juices, in temperatures of 10 and 60oC. The juice proportion were defined by response surface methodology to mixture. Rheological data were obtained in a Haake Rotovisco model RV 20 and rheograms were fitted with Ostwlad- De Waele. The rheological parameters were used as response for the experimental designs. It was observed that the parameters consistency index and flow behaviour index, in the two temperatures, were better described with the linear and quadratic model, respectively.

Microestrutura da fibra alimentar do albedo de laranja: um estudo por técnicas físicas e análise de imagens

The food fibers are consumed naturally in cereals, fruits and vegetables, and they are also added in a concentrated form in processed foods. Different fiber sources have different structures and chemical composition that will define their nutritional or technological purpose. This research aims the characterization of orange albedo dietary fiber submitted to two methods of drying (conventional and lyophilization) and split by granulometric intervals. For the density determinations, surface area, porosity and pore size distribution it was used classical techniques of the particulate systems tecnology and it was compared whit images of scanning electron microscopy. The results showed that the drying method influence more in the material pore volume reduction, this is also visualized in the microstructural characteristics reveled by image analysis. The granulometric interval of particulate fiber showed itself inversely proportional to the material density and material specific surface area. The orange albedo dietary fiber showed structural characteristics that allow the diversification of new food products with high nutritional and commercial value.

Influência de diferentes teores de sólidos insolúveis suspensos nas características reológicas de sucos de abacaxi naturais e despectinizados

Estudou-se, neste trabalho, a influencia dos solidos insoluveis suspensos nas caracteristicas reologicas de sucos de abacaxi in natura e sucos tratados com enzima pectinolitica. Cada um dos dois tipos de suco foi estudado atraves de seis fracoes, divididas em quatro peneiradas, uma centrifugada e uma integral, representando seis teores de solidos insoluveis suspensos. Os dados reometricos foram coletados atraves de um reometro Haake rotovisco e os dados experimentais ajustados pelo modelo de Mizrahi-Berk. Das seis fracoes in natura, quatro apresentaram comportamento pseudoplastico, uma caracterizou-se como newtoniana e outra como dilatante enquanto das seis fracoes tratadas enzimaticamente cinco apresentaram comportamento pseudoplastico e uma caracterizou-se como newtoniana. O teor de solidos insoluveis suspensos mostrou-se o principal fator responsavel pelo comportamento reologico dos sucos de abacaxi naturais e despectinizados.

Efecto de la temperatura sobre las proteínas de lactosuero

In the pres ent work, whey protein fouling phenomenon was studied, when fowed in the inner tube of a double tube heated by hot water which fows in the ring space between them. The fouling kinetics depends on the mass transfer effects, which is a function of protein solubility. To describe the fouling kinetics a calculus algorithm was developed, having as subsidy the protein solubility itself. The proteins solubility were determined in a separate investigation. Results showed that the time necessary for the tube´s inner radius to decrease in 30% of the original radius was smaller for high temperatures. Besides, whey protein deposition was greater at the tube´s entrance than in its exit. Therefore, the rate of radius reduction was faster in that area. The experimental check for the algorithm was conducted in a pilot plant.