Avaliação de diferentes processos de extração na obtenção de óleo de farelo de arroz

Abstract

Rice bran oil (RBO) is a natural rich source of antioxidants and contains a balanced fatty acids composition, which is of great interest for application in food, cosmetic and pharmaceutical industries. Therefore, the objective of this study was to investigate the rice bran oil extraction using supercritical fluid extraction with carbon dioxide (SFE-CO2), SFE-CO2 assisted by ultrasound (US) and with compressed liquefied petroleum gas (LPG). Also, the antioxidant activity and chemical composition of extracts were evaluated. In the SFE, pressure (150 250 bar) and temperature (40 80 °C) conditions were studied, while in the SFE + US the variables studied were power (160 320 W) and time of ultrasound application (40 120 min). In the extraction using LPG, the pressure (5 25 bar) and the temperature (20 30°C) effects were investigated. The antioxidant activity of the extracts was assayed by DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging method and the chemical composition by gas chromatography mass spectrometry (GC-MS). The maximum yields achieved of RBO were 12.68%, at 250 bar and 40 °C, in the SFE, 12.65%, using 160 W for 40 min in the SFE assisted by US, and 12.07% at 25 bar and 40°C in the extraction with compressed LPG. The antioxidant activity of the extracts ranged from 54.55 71.67% in the SFE, 69.26 72.42% in the SFE + US and 63.55 67.49% in the extraction with compressed LPG. The main antioxidant compound found in different processes was the β-sitosterol, which is one of sterols that compose the γ-oryzanol. The US application in SFE accelerated the process and increased the RBO yield in approximately 27%. In the SFE and SFE + US processes were spent 120 min to obtain 81.93% and 64.38%, respectively, while extraction with compressed LPG took only 5 minutes to extract 78.17% of oil, showing high oil solubility in this solvent. In general, the processes performed well in the recovery of rice bran oil, being considered as technically viable alternatives to conventional processes.