Qualidade bioenergética do resíduo de açaí sob diferentes condições de estocagem e tempo.

Abstract

The production and commercialization of the açaí fruit have contributed significantly to the agro-industrial development of the Amazon region. However, such progress has caused exponential growth of post-processing waste, the açaí residue, with potential for bioenergy generation. Inadequate storage of açaí residue depreciates its biomass. Therefore, the objective of this work was to analyze the effect of storage conditions and time on the modification degree of the bioenergetic quality of the açaí residue. Açaí seeds were stored in a covered greenhouse for nine months under three conditions: immersed in deionized water, under the ground, and in plastic bags. Physical and chemical analyzes of the fresh residue were performed at time zero and after 30, 60, 180, and 270 days of storage. Analyses of water-soluble extractives, Fourier transform infrared spectroscopy, thermogravimetric in an inert atmosphere, and thermogravimetric in the oxidative atmosphere were performed for the fresh residue and at the end of the storage time. All açaí residue storages evaluated caused degradation. However, storage in soil and plastic bag increased concentrations of the biomass structural components. As a result, the fixed carbon content of the biomass and the calorific value increased significantly, balancing small reductions in the biomass density. In addition, moisture was reduced with these storage methods, and ash content increased. After 30 days of storage, there was the lowest moisture content and the highest fixed carbon content compared to the fresh residue and the other days of storage. On the other hand, storage in water significantly degraded the residue, but without concentration of structural components. Humidity remained high, and density decreased significantly. The combustibility and pyrolysis of açai residue stored in water and in plastic bags presented small changes when compared to fresh açai residue. On the contrary, storage in soil, despite the positive changes in bioenergetic properties, adversely altered the combustibility and pyrolysis of the açaí residue. In combustibility, açaí residue has delayed ignition and very intense mass loss in the second stage. For pyrolysis, açaí residue was more stable by this storage method. This work proved the bioenergetic potential of the açaí residue, highly resistant to the weather caused by the environment, even with its frequent improper disposal.