INTERNATIONAL JOURNAL OF FOOD SCIENCE AND TECHNOLOGY, vol.42, no.3, pp.359-365, 2007 (SCI-Expanded)
The capacity of sepiolite to adsorb colouring matters in olive oil was studied. The effects of adsorption time, temperature and solid:liquid ratio were selected as parameters. The effect of bleaching of olive oil was evaluated for determining the % free fatty acid (FFA), % bleachability and residual carotene by using both thermally activated sepiolite (AS) and acid-activated sepiolite (AAS). Results reveal that thermally acid-activated sepiolite was more efficient than thermally activated sepiolite. The adsorption equilibriums of carotene and FFA on AS and AAS were described by the Freundlich models. A higher adsorption coefficient (K) was observed for AAS (K-carotene = 2.73 x 10(-3)mgg(-1), K-FFA = 0.98mgg(-1)) compared to AS (K-carotene = 2.63 x 10(-7)mgg(-1), K-FFA = 0.21mgg(-1)). Moreover, the rate constants obtained for carotene and colour by using AAS (k(color) = 0.0241 min(-1), k(carotene) = 0.0217min(-1)) were higher than that of AS (k(color) = 0.01min(-1), k(carotene) = 0.0165min(-1)).