Acid activation of sepiolite clay to bleach edible oils

In order to enhance palatability and storage of edible oils, it needs to refine the oil in several stages. Bleaching is one of the most important stages of refining process. Acid activation is usually used to improve the bleaching capacity of the clay and reduce environmental threats and energy usage. On the other hand, pigment removal would lead to increasing of oil shelf life and consumer acceptance. In this study, sepiolite clay was activated in three different conditions of time (8-12 hours), temperature (70-90 °C) and acid amount (15%-45% w/w) using response surface methodology (RSM) and D-Optimal design. The oils were then bleached in 90C for 30 minutes by 1.5% bleaching clay. The results showed that the best condition of acid activation was obtained using 32.25% acid at 83.8 °C and bleaching time of 8.75 hours. This condition decreased chlorophyll and β-carotene amounts from 12.98 and 39.83 to 4.02 and 18.86 ppm, respectively. The maximum bleaching capacity of activated sepiolite clay was found to be 90.85%.