Abstract
Abstract The objective of this work was to evaluate the efficacy of ethyl acetate as a solvent in the extraction of macauba kernel oil (MKO) using ultrasonic-assisted extraction (UAE). It was shown that more MKO oil could be extracted with the use of larger amounts of solvent, higher temperatures and longer extraction times. Thus the maximum oil yield (40.61%) was obtained by UAE at 60 °C for 45 min, using a solvent to kernel ratio of 12 (mL g-1), obtaining a higher yield than that obtained with n-hexane under the same experimental conditions. UAE was favorable for this oil extraction (p < 0.05), presenting a yield close to that reported for classical extraction but with a shorter extraction time and smaller solvent volume. Lauric acid corresponded to ~44% of the MKO composition. The oils presented low free fatty acid contents (<0.80% wt), and the phytosterols, campesterol and β-sitosterol, were identified in the MKO with higher levels in the oil obtained by UAE.
Highlights
The Brazilian Macauba palm tree (Acrocomia aculeata) produces fruits of which the kernel represents approximately 6.3% (Evaristo et al, 2016), with a productivity of between 1500 and 5000 kg of oil per hectare per year
The present study aimed to evaluate the effect of the process variables on the ultrasonic-assisted extraction of macauba kernel oil, and to establish conditions that maximize oil extraction by this technique using ethyl acetate as the solvent
3.2 Ultrasound-assisted extraction Table 2 shows the experimental conditions used to obtain macauba kernel oil (MKO) by ultrasonic-assisted extraction (UAE) using ethyl acetate as the solvent, and the oil yield obtained under these conditions
Summary
The Brazilian Macauba palm tree (Acrocomia aculeata) produces fruits of which the kernel represents approximately 6.3% (Evaristo et al, 2016), with a productivity of between 1500 and 5000 kg of oil per hectare per year. In the ultrasound-assisted process, the phenomenon called cavitation occurs, due to the formation of low frequency ultrasonic waves (above 20 kHz), which propagate in a liquid medium, creating something called microbubble shock. These shocks increase or decrease their size, generating compression and expansion until the bubbles implode near the solid, promoting the rupture of the vegetable cell wall and aiding in the extraction of the intracellular material (Zheng & Sun, 2005; Tao & Sun, 2013; Ferreira et al, 2014; Chemat et al, 2017)
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