Secagem de resíduos de frutas em secador roto-aerado

Abstract

The reuse of agroindustrial residues is essential to avoid the waist, which implies less social, economical and environmental impacts. Therefore, one alternative is the process of drying, in which one possible type of dryer is roto-aerated dryer, developed in FEQUI/UFU. It provides a better contact between the particles and the fluid (air) than conventional rotator dryer, because of the new arrangement of the drying air that raises heat and mass transfer coefficients, reducing the energy requirement. In this work, the acerola residue s characterization showed the presence of antioxidant compounds, that turns viable its drying process. Infrared drying process allowed to observe the benefic effect of pulverized ethanol over acerola seeds surfaces, a pre-treatment that brought good results to drying process as well as phenolic and flavonoids contents after the process. In roto-aerated dryings this pretreatment was favorable to minimum operational conditions, that represents temperature and air velocity equal to 80 ºC and 1.5 m/s. However, for intermediate conditions (115 ºC and 2.25 m/s) and extreme conditions (150 ºC and 3.0 m/s) this pre-treatment didn t imply significant increases of humidity removal. The drying of acerola residues without pretreatments in roto-aerated dryers showed that this equipment is a good alternative for its drying, which allowed until 45,8% humidity removal in a 159 ºC and 2.25 m/s condition, with 3.2 min of residence time of the acerola seeds in the dryer. For the extreme condition (150 ºC and 3.0 m/s) only three passages of the seeds were necessary in the dryer, so that the final humidity was 6.7%. Furthermore, this dryer generates a homogeneous final product because of the high level of mixture, which is capable of processing a high volume of material. It was also observed that bioactive compounds, except citric acid ones, were higher in the seeds after the drying process than before it.