Abstract
The main goal of the present work was to evaluate the application of ultrasound as a previous step to promote the substrates pre-emulsion in the hydrolysis reaction of macauba kernel oil (MKO). The ultrasound effect on the substrates pre-emulsion was evaluated on the free fatty acid (FFA) content, as well as the process variables (reaction time, percentage of catalyst Lipozyme® RM IM, and buffer solution). Reactions carried out with the substrates pre-emulsion presented higher FFA production, up to a 40 wt% increase in 1 hour of reaction, yielding 80 wt% of FFAs in 8 hours. The use of catalyst in the reaction medium, from 5 to 15 wt%, favored the FFAs production in 2 hours of reaction. Addition of 25 to 100 wt% of buffer solution led to 86 wt% of FFAs in 4 hours of reaction. Enzyme recycling resulted in a slight decrease in the FFA content, although the catalyst had maintained 85% of its initial activity after 30 h of use. Therefore, the ultrasound pre-emulsion previous step allowed a more efficient hydrolysis reaction of MKO, leading to an increase of up to 40 wt% on the FFA content, when compared to the hydrolysis without such step.
Key words
enzymatic catalysis; free fatty acid; hydrolysis; ultrasound
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with substrates pre-emulsion and 
without substrates pre-emulsion. Means followed by the same letter, for the same reaction time, do not statistically differ (p<0.05).
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15 wt% based on the substrates mass) on the FFA content (reactions performed at 55 °C, 50 wt% buffer solution, and stirring rate of 400 rpm). Means followed by the same letter, for the same reaction time, do not statistically differ (p<0.05).
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100 wt% based on the oil mass) on the FFA content (hydrolysis carried out at 55 °C, stirring rate of 400 rpm, and 10 wt% Lipozyme® RM IM). Means followed by the same letter, for the same reaction time, do not statistically differ (p<0.05).
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