ABSTRACT
The effects of the use of solvents (96% ethanol and PEG 400), solute ratios: solvent (1: 4 and 1: 6 w/w), extraction temperatures (50 and 60 °C) and leaching techniques (conventional and assisted by ultrasound) on the concentration and time of extraction of bixin from Achiote (Bixa Orellana L.) were evaluated. The extraction kinetics were constructed, and their orders were determined. The experimental values were adjusted through the mathematical models of Peleg and Azuara. ANOVA was used based on a 23 design, blocking type of technology. The kinetics showed two stages of extraction: rapid and slow. The reaction orders were decimal numbers, which indicates the complexity of the extraction mechanism. The highest orders of reaction (2.97 and 2.075) were presented with extraction with ultrasound-assisted and ethanol as solvent, at 50 and 60 °C and solute solvent ratio 1: 4 and 1: 6, respectively. The concentration of Bixin was increased by approximately 30% by increasing the temperature. The Azuara model presented the highest adjustment with a standard error < 0.1. The conventional leaching with PEG-400 required the lowest activation energy (9.2 kJ / mol) and with this treatment in 66 min the highest concentration of bixin (2.74 mgBix / gExt) was obtained. It was concluded that ultrasound-assisted leaching facilitates the extraction of bixin pigment, and the use of PEG 400 solvent is useful to obtain higher yields.
