Sterolic Composition of Neutralized Oils Bleached with Clays Activated with Ultrasound

Clays are activated by a classic process and realized in relatively high temperatures. Increasing the clay surface acidity leads to the increase of the specific surfaces of clays with deeper destruction of their crystal lattice; with the training of amorphous silica. This later can cause many degradation reactions such as isomerization of polyunsaturated fatty acids, decomposition of unsaturated fatty acids and sterols, and to dehydration of sterols which leads to steradienes formation. With the aim to prepare bleaching earths with high efficiency, and having less negative effects, ultrasonic waves were introduced during activation process. The experimental conditions of this new activation process allowed the acid concentration and activation time to be considerably reduced. The influence of activated clays with ultrasound on physico-chemical properties of bleached oils, mainly on fatty acid composition, sterols, and steradienes was investigated. It was proved 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. The noticed losses in sterols were suggested to be strongly dependent on the influence of activation process, mainly on surface acidity of bleaching earths.