High-power ultrasound treatment for canola oil bleaching Brassica napus L.

Abstract: Considering that canola oil (Brassica napus L.) is one of the most consumed oils in Mexico, the industry has begun to look for alternatives that allow it to improve its bleaching process, since, the conventional method used is a process with high temperature (140 °C), a long processing time (180 min), and a high percentage of bleaching clay (3% w/w). The latter being a latent risk of soil and water pollution, in the absence of a method that allows its reuse. Thus, high-power ultrasound is proposed, for the bleaching of oil, reducing the amount of resources in the step. Therefore, the aim of this study was to analyze the reduction of pigments in crude oil using high-power ultrasound treatments (40 kHz, 600 W), applying 9 ultrasonic treatments: processing time (60, 75 and 90 min), bleaching clay percentage (1, 2 and 3 %) at 60 and 80 °C. The study variables were chlorophylls (a and b) and carotenoids using contour plots. The results obtained showed that the areas with the highest reduction of pigments (chlorophylls and carotenoids) when using 60 °C, were those between 60-90 min and 1-2% clay (approx. 98%), while at 80 °C, the best results were observed with treatments between 75-90 min with 2-3% clay (90%). Thus, when optimizing them to define the ideal conditions to maximize the reduction using a smaller amount of clay and a shorter time. These conditions were at 60 °C, 68 minutes, and 1% clay, whereas at 80 °C, 65 minutes and 1.5% clay. In this way, the results obtained have shown that ultrasonic treatments can reduce more than 90% of pigments (main impurity in the oil), and at the same time it may reduce the original process conditions with favorable results.