Determination of optimal conditions for selected adsorbent combinations to recover used frying oils

The treatment of frying oils with adsorbents could practically extend the frying life of oils. Combined synthetic adsorbent treatment of used frying oils was studied the first time. The combinations of four commonly used filter aids: Britesorb (Br), Hubersorb 600 (HB), Frypowder (Fr), and Magnesol (Ma) were evaluated for frying oil recovery. AOCS official methods were used to evaluate their adsorptiveness, including free fatty acids (FFA), conjugated diene value, total polar components, oxidative stability index (OSI), and absorbance at 420 nm. The selected combinations HB+Ma+Fr and HB+Ma+Br exhibited consistent high recovery abilities on various used oil samples. A 3, 3, and 2% HE, Ma, and Fr, respectively, for the first combination (F), and 2, 3, and 2% HE, Ma, and Br, respectively, for the second combination (B) were the most effective. The optimal treatment duration was 6-9 min and 3-6 min for combinations F and B, respectively, which reduced FFA by 82.6-87.6%, absorbance by 26.8-32.6%, and Foodoil Sensor readings by 5.6-8.6%. Addition of antioxidant, such as 50 ppm butylated hydroxytoluene and 50 ppm propyl gallate, increased the OSI value by 48.9-80.8%. Such adsorbent combinations may be used in practical operation to extend frying life of frying oils and improve the healthy aspects of used frying oils.