RHEOLOGICAL BEHAVIOR OF MIXED PULP OF ‘SERIGUELA’ AND Spirulina platensis FORMULATED WITH MALTODEXTRIN

The correlation between shear stress and shear rate is essential to know the rheological characteristics of a fluid, with numerous food applications. This study aimed to determine the influence of maltodextrin concentration on the apparent viscosity of a mixed pulp of ‘seriguela’ (Spondias purpurea L.) and Spirulina platensis. The following formulations were used: pulp = seriguela pulp in natura, P+S = seriguela pulp added with 3.0% of powdered S. platensis, M10 = P+S with 10% maltodextrin, M20 = P+S with 20% maltodextrin, and M30 = P+S with 30% maltodextrin. The rheological behavior was determined using a Brookfield DV-II programmable viscometer, with adjustment of experimental data to the Power-Law, Casson and Bingham rheological models, using the Statistica Software, version 10.0. There was a decrease in apparent viscosity with the increase in shear rate in all samples, showing pseudoplastic properties, being characterized as a non newtonian fluid. It was observed that higher shear stress on the fluid the higher its ordering, consequently the lower its viscosity. The Power Low, Casson and Bingham rheological models well adjusted to the experimental data. For the Power Law model, the coefficients of determination (R2) were higher than 95.79%, mean squadratic deviations (MSD) lower than 2.37, and mean percentage deviation (P%) lower than 3.50%. For the Casson rheological model, the parameters were R2 > 96.88%, MSD < 0.16 and P < 1.65%; for the Bingham model, they were R2 > 94.95%, MSD < 4.78 and P < 2.67%. Therefore, the Casson rheological model was the best adjusted to the experimental data. The effect of temperature on apparent viscosity was described by the Arrhenius equation, and P+S and M30 were the samples most influenced by the temperature with high activation energy values of 8.86 and 8.16 KJ.g-1.mol-1, respectively.