Comparação de métodos físicos de extração de carboidratos do farelo de arroz

Abstract

In the past years, agroindustrial production has increased significantly and therefore there is a greater generation of waste. The rice bran (fad), one of the main agricultural residues generated today, comes from the polishing of grain that contains significant amounts of carbohydrates, proteins, lipids and minerals. The aim of this work was to extract the carbohydrates (chos) by two different methods: ultrasonic treatment in probe and hydrothermal treatment. The chos extracted under the best process conditions were evaluated by fourier transform infrared spectroscopy (ftir) and ultra high performance liquid chromatography (uhplc). The fad was submitted to physical-chemical characterization and presented a high content of chos, being of 61,30%. In the ultrasonic treatment, two experimental design was conducted, in which the studied variables were fad.water-1 (g.L-1), power (w), time (min), temperature (°c); in the hydrothermal treatment the variables were fad.water-1 (g.L-1), ph, time (min). The obtained extracts were quantified by total carbohydrates content ( antrona method) and the chos were precipitated in 80% ethanol, centrifuged and lyophilized. Posteriorly, the chos samples were evaluated in ftir and the functional groups were identified. The chos were also hydrolyzed and subjected to determination of the carbohydrate profile by uhplc. When the fad was subjected to the ultrasonic treatment under conditions of fad.water-1 (65 g.L-1), power (350 w) and time (20 min), extracts with 0.60 g cho.g-1 fad were obtained, with 78,30% yield. On the other hand, in the hydrothermal treatment, the best extraction conditions were obtained in the ratio fad.water-1 (100 g.L-1), ph (6) and time (35 min), obtaining extracts with 0.46 g of cho.g-1 fad, and yield of 75,04%. The chos of the fad analyzed in ftir indicated the presence of functional groups at the same wavelength of other chos, such as stachyose. However, in uhplc it was possible to quantify only glucose. In the comparison of the methods, it was possible to observe that the ultrasonic treatment presents a high capacity of extraction of chos in less time, not requiring organic solvents and treatment of residues, being considered the most efficient.