Cinética de secagem e armazenamento de spirulina platensis

Abstract

The Spirulina platensis is a multicellular photosynthetic cyanobacteria blue -green coloring, and has been used in several countries in aquaculture as food for human and animal consumption. The Spirulina platensis was provided by the company Vital Brazil, located in Anápolis- GO. The objective of the first chapter was to determine and model the drying kinetics of Spirulina platensis in different temperatures (30, 40, 50 and 60 °C). It adopted a completely randomized design and treatments were drying temperatures. The initial water content of product was determined according to the analytical standard AOAC. The product was subjected to oven drying at temperatures of 30, 40, 50 and 60 °C. The samples were placed on removable stainless steel trays with screenhouse bottom, in three repetitions. The temperature and RH of ambient air were monitored by means of a thermo-hygrometer. During the drying process, the trays with samples were weighed periodically until constant weight. Later, the data were submitted to analysis of variance by F test at 5%. Mathematical models were fitted to the experimental data of drying, using Statistica Software 12.0. The effective diffusion coefficient was obtained by fitting the mathematical model of liquid diffusion. It can be concluded that: the time required for Spirulina platensis achieve constant mass was 7.00; 4.58; 3.83 and 3.25 hours for temperatures of 30, 40, 50 and 60 °C, respectively; recommended the model to predict the drying phenomenon of Spirulina platensis were Midilli the mathematical model for the temperatures 30 , 40 and 50 °C, and the diffusion approximation model for the temperature 60 °C; The diffusion coefficient has increased with the temperature increase, with values of 3.343x10-8 to 14.881x10-8 m2s-1 for the temperature range 30 to 60 °C; and has an activation energy of liquid diffusion 39.52 kJ.mol-1. In the second chapter the samples were dried at temperatures of 30, 40, 50 and 60 °C in an oven with forced air circulation until they reach the great water content of 8% ± w.b. They were crushed and placed in polyethylene packages. The analysis were carried out: the crude protein content was determined using the Kjeldahl method, an ash content was determined by weight difference by the muffle, the color analysis was verified the values L, a*, b*, using colorimeter ColorQuest XE, the analysis of Chlorophyll-a, it was carried out through specific methodology adaptations. Two experiments were conducted. The Experiment 1: analyzed the effect of drying of Spirulina platensis at temperatures of 30, 40, 50 and 60 °C. Witness analyzes were performed (product in nature), and the time 0 (after drying at different temperatures). It was applied Dunnet test using Assistat 7.7 software. Microscopic analyzes were also made Spirulina platensis using the Leica ICC50. The Experiment 2: analyzed the effect of drying of Spirulina platensis in storage for 6 months. The completely randomized design was used in a factorial designs (4 x 7), four drying temperatures (30, 40, 50 and 60 °C) and 7 storage periods (0, 30, 60, 90, 120, 150 and 180 days). The experimental data were subjected to analysis of variance by F test at 5% through Software Statistica 12.0. The results concluded that: in the temperature range of 40 to 50 °C occurred smaller percentages of ash and higher in protein content, an increase in the amount of chlorophyll-a with increasing drying temperature, for the color parameters, a whitening of Spirulina platensis was observed.