Luiz Antonio Viotto

Concentração da vinhaça por microfiltração seguida de nanofiltração com membranas

The objective of this work was to evaluate vinasse concentration by microfiltration (MF) followed by nanofiltration (NF). The experiments were carried out in the laboratory, at 60oC and 500 rpm, using vinasse with 2.8% total solids (TS) in order to assess the influence of pressure on permeate flux and TS retention. Pressure ranged from 1.0 to 3.4 bar for MF, and from 15 to 35 for NF. Amembrane cellulose with molecular weight cutoff of 100 kDA was used for MF, and a polyethersulfone (PES) membrane of 300, 500, and 1,000 Da was used for NF. MF at 1.8 bar was selected, because of its good flux and lower energy consumption, and the permeate obtained was subjected to NF. NF showed TS retention of 47-75%, and the highest permeate flux was obtained with PES 1,000 Da at 35 bar. The final concentrate has 4% of TS and is considered appropriate for soil use, intermsof chemical oxygendemand andTS content.

Ultrafiltration performance of PVDF, PES, and cellulose membranes for the treatment of coconut water (Cocos nucifera L.)

Ultrafiltration (UF) inhibits the enzymatic activity which is responsible for color changes of coconut water without the need for heat treatment. In the present study, UF performance in terms of the permeate flux and enzymatic retention of the coconut water was evaluated at laboratory unit (LU) and pilot unit (PU). The membranes studied were polyethersulfone 150 kDa (UP150), polyvinylidene fluoride 150 kDa (UV150) and cellulose 30 kDa (UC030). The UP150 membrane showed the best permeate flux. The UC030 membrane showed the lowest flux, but it resulted in 100% enzymatic retention, while the other membranes showed enzymatic retentions between 71 and 85%. The application of the UC030 in the pilot unit (PU) resulted in a flux value higher than that obtained in the LU due to the tangential velocity effect. The UC030 membrane has proved adequate for industrial applications.

Drying of sicilian lemon residue: influence of process variables on the evaluation of the dietary fiber produced

In this study, the effect of the process variables of the air-drying of Sicilian lemon residues on some technological properties of the fibers produced was studied. The determination and modeling of desorption isotherms were used to establish the equilibrium moisture content at 60, 75, and 90 °C using the static method with 8 saturated salt solutions. The best fit was obtained with BET and GAB models. The drying process was conducted in a vertical tray dryer and delineated according to a central composite experimental design (22) using the following as factors: air velocity (0.5, 0.75 and 1 m/s) and temperature (60, 75, and 90 °C), and it presented a good fit to the exponential model (R2 > 99.9%). The experimental design responses evaluated were the technological properties of the fibers: water-holding, oil-holding, and swelling capacity. Since these properties were present in high levels, the lemon residues could be used to increase content of fibers in foods resulting in the addition of nutritional benefits for the consumers.

Efeito do uso de cultura adjunta (Lactobacillus helveticus) na proteólise, propriedades viscoelásticas e aceitação sensorial de queijo prato light

Proteolysis, viscoelastic properties and sensory acceptance of reduced fat Prato cheeses made with and without adjunt culture (AC) were evaluated. The cheeses were made from microfiltered milk. Two different treatments were replicated twice: control cheese was made only with traditional starter, while the other was made with the addition of both AC (Lactobacillus helveticus) and traditional starter. Cheese composition was determined after 5 days of manufacture. Proteolysis and rheological properties were evaluated after 5, 25 and 45 days. Viscoelastic parameters were obtained using relaxation tests. Cheese sensory properties were evaluated using acceptability tests. There was no statistical difference (p>0,05) in cheese composition. The proteolysis depth indexes were significantly higher (p 0.05) in viscoelastic parameters for cheeses made with and without AC. Sensory acceptability tests indicated significant difference (p<0.05) between samples for flavor, texture and global impression. Cheese made with AC was better graded than cheese made only with starter. Buying intention grades showed that 70% consumers would certainly or probably buy cheese made with AC, while only 43.4% would behave the same with control cheese.

Enzyme optimization to reduce the viscosity of pitanga (Eugenia uniflora L.) juice

The aim of this work was to separately evaluate the effects of pectinase and cellulase on the viscosity of pitanga juice, and determine the optimum conditions for their use employing response surface methodology. The independent variables were pectinase concentration (0-2.0 mg.g–1) and cellulase concentration (0-1.0 mg.g–1), activity time (10-110 min) and incubation temperature (23.2-56.8 °C). The use of pectinase and cellulase reduced the viscosity by about 15% and 25%, respectively. The results showed that enzyme concentration was the most important factor followed by activity time, and for the application of cellulase the incubation temperature had a significant effect too. The regression models showed correlation coefficients (R2) near to 0.90. The pectinase application conditions that led to the lowest viscosity were: concentration of 1.7 mg.g–1, incubation temperature of 37.6 °C and incubation time of 80 minutes, while for cellulase the values were: concentration of 1.0 mg.g-1, temperature range of 25 °C to 35 °C and incubation time of 110 minutes.

Efeito do tratamento enzimático sobre a viscosidade e os teores de fibra e pectina em suco de pitanga (Eugenia uniflora L.)

The aim of this work was to evaluate the effect of the enzymatic treatment on the viscosity values and fiber and pectin contents of pitanga juice, applying commercial enzymes. Different combinations of pectinase (Pectinex Ultra SP-L) and cellulase (Cellubrix-L), giving a total mass of enzyme of 0.1%, were evaluated. The results indicated a low value for pectin (<0.003%) and a significant reduction in the fibre content after the enzymatic treatment. The application of 0.025% of pectinase with 0.075% of cellulase caused a greater reduction in fibre content and hence a lower viscosity of the juice. At the same time, a minimum of 0.05% of Pectinex Ultra SP-L was required to obtain the lowest pectin concentrations. The combined application of these enzymes resulted in a lower viscosity juice whose rheological behaviour was close to Newtonian, and hence the Power Law model would be more suitable for use in mathematical modelling.

Comportamento reológico de constituintes do ovo

2 500, 1995) in the steady state, in a range of temperatures (5-60 °C), with cone and plate geometry for the reconstituted egg yolk and concentric cylinders for the other samples, both geometries in stainless steel. The samples of pasteurized whole egg, pasteurized egg white and reconstituted egg white presented Newtonian behaviour, while the reconstituted whole egg, reconstituted egg yolk and pasteurized egg yolk, pseudoplastic behaviour. The samples of reconstituted egg yolk and whole egg presented higher viscosities than the pasteurized samples. The experimental data for shear stress versus shear rate were fitted to the Ostwald- de-Waelle, Newtonian, Casson and Herschel-Bulkley models. The parameters of these models were determined by a nonlinear regression analyses. The effect of temperature on the apparent viscosity and consistency index was described by the Arrhenius relationship.

Effect Of Adjunct Culture (lactobacillus Helveticus) On Proteolysis, Viscoelastic Properties And Sensory Acceptance Of Reduced Fat Prato Cheese [efeito Do Uso De Cultura Adjunta (lactobacillus Helveticus) Na Proteólise, Propriedades Viscoelásticas E Aceitação Sensorial De Queijo Prato Light]

Proteolysis, viscoelastic properties and sensory acceptance of reduced fat Prato cheeses made with and without adjunt culture (AC) were evaluated. The cheeses were made from microfiltered milk. Two different treatments were replicated twice: control cheese was made only with traditional starter, while the other was made with the addition of both AC (Lactobacillus helveticus) and traditional starter. Cheese composition was determined after 5 days of manufacture. Proteolysis and rheological properties were evaluated after 5, 25 and 45 days. Viscoelastic parameters were obtained using relaxation tests. Cheese sensory properties were evaluated using acceptability tests. There was no statistical difference (p>0,05) in cheese composition. The proteolysis depth indexes were significantly higher (p 0.05) in viscoelastic parameters for cheeses made with and without AC. Sensory acceptability tests indicated significant difference (p<0.05) between samples for flavor, texture and global impression. Cheese made with AC was better graded than cheese made only with starter. Buying intention grades showed that 70% consumers would certainly or probably buy cheese made with AC, while only 43.4% would behave the same with control cheese.