Role of different bleaching earths for sunfl ower oil in a pilot plant bleaching system

The purpose of present study is to investigate the effi ciency of different kinds of Turkish commercial bleaching earth materials for changes in different colour pigment concentrations in neutralized sunfl ower oils. The bleaching experiments were performed in a pilot system under at stable vacuum (50 mmHg) and temperature (100°C) for 30 min. By examining the changes in chlorophyll, ?-carotene and red colour, bleaching process parameters such as type and dosage of the bleaching material were optimised. The sorption characteristics of colour pigments were evaluated using common adsorption isotherms and Scatchard plot analysis. Ads-3 acid-activated earth material at 1% (w/w) per samples was found to be the most appropriate sorbent and the amount of sorbed pigments was calculated as 1.01x10-4 mmol/g ads. for chlorophyll, 1.15×10-3 mmol/g ads. for carotene and 1.70 red on Lovibond colour scale. The procedure indicated that this system can be easily adapted to the actual oil refi ning systems.