Oxidative stability of neutralized oils bleached with clays activated with ultrasound

• Limits of the principal activation parameters were defined to have adsorption capacity without destroying the clay.
• Significant interaction term was deduced between optimum conditions of the new activation process and the oxidative stability of bleached oils.
• Activated clay prepared with the lowest acid concentration met minor compounds during processing.

Ultrasonic waves were applied during activation process of Tunisian clays, to contribute to bleaching earths with high performance. Activation was performed at optimal frequency (20 KHz) and ultrasound amplitude of 28–50%. Combination of the conventional technique (classic activation process), with the use of very low acid concentration solutions (0.5 M) with ultrasound gave the best results. This new developed process was efficient, economic and rapid. The effectiveness of optimal activated clays was very important, according to the bleaching index of neutralized pomace-olive oils (86%).The influence of activated clays with ultrasound on oxidative stability of bleached oils. It was improved that these clays, activated with the new technique, led to the removal of unacceptable compounds with the least possible losses of oil and desirable fractions. No significant losses in natural antioxidants (α-tocopherol), noted in treated oils, which were at the origin of an important resistance to oxidative stability (high OSI).