master arthur

Supercritical CO₂ extraction of bioactive compounds from dedo de moça pepper (Capsicum baccatum L. var. pendulum) assisted by ultrasound

Author: Arthur Luiz Baião Dias (2015)

Abstract: Supercritical fluid extraction (SFE) has been employed as alternative to conventional processes of extraction and fractionation of bioactive compounds. Among the most useful solvents in supercritical processes, carbon dioxide has been the most employed because of some advantages like low toxicity (GRAS solvent), low flammability and being inert. Generally, the capacity of a SFE unit is changed with the application of combined techniques, such as ultrasonic waves. Ultrasonic waves are capable of generating cavitational bubbles that can disrupt the cell walls of vegetable matrixes, favoring the solvent/solute contact, and thus increasing the extraction yield. The objective of this work was to obtain extracts with bioactive compounds from the pepper variety “dedo de moça” (Capsicum baccatum L. var. pendulum) through SFE without and with ultrasound, though soxhlet with methanol, ethanol, ethyl acetate and hexane and through low pressure techniques using ultrasound with methanol and ethanol. In SFE the pressure ranged from 15 to 25 MPa, ultrasound power from 200 to 600 W and the time of ultrasound application from 40 to 80 min. In low pressure extraction the temperature ranged from 40 to 60 °C, ultrasound power from 200 to 600 W and ultrasound application time was 20 min to methanol and 60 min to ethanol. The CO₂ mass flow rate was fixed at 1.7569x10^-4 kg/s. Kinetic SFE curves were plotted to verify the influence of the processes variables. Two mathematical models were applied, Sovová (1994) and Pardo et al. (2015), to evaluate how each model fits to the experimental data. Total capsaicinoids were identified and quantified in the extracts through ultra high performance liquid chromatography (UHPLC-DAD). Phenolic compounds and antioxidant capacity were quantified through spectrophotometer analysis in the visible region. The extracts obtained at low pressure with ultrasound showed the highest phenolic contents and antioxidant capacities by DPPH, while the extracts obtained by soxhlet showed the highest oleoresin yield, antioxidant capacity by FRAP and total capsaicinoids. In SFE, the application of ultrasound was capable to raise the global yield of oleoresin from dedo de moça pepper approximately 45% at the best condition (25 MPa, 40 ºC, 600 W e 80 min). The application of high ultrasonic power in SFE decreased the concentration of total phenolics compared to SFE without ultrasound. The antioxidant capacity was higher in SFE without ultrasound for both techniques DPPH and FRAP. The total capsaicinoids yield increased in SFE with ultrasound approximately 12% at the best condition (25 MPa, 40 °C, 200 W and 40 min). The models of Sovová (1994) and Pardo et al. (2015) provided good adjustments of the mass transfer processes and fitted well the evaluated kinetic curves. The morphology of the vegetable matrix was analyzed through field emission scanning electron microscopy (FESEM), and changes in the sample structure caused by ultrasound were observed.