The effects of refining steps on Kilka (Clupeonella delicatula) fish oil quality

Kilka fish are known as the main industrial and pelagic species of Iran that are captured abundantly in the southern Caspian Sea. This study was conducted to survey the effectiveness of refinement steps on Kilka (Clupeonella delicatula) crude oil quality and fatty acid profiles. Neutralization, bleaching, winterization and deodorization were performed on crude oil with deodorization done under two different conditions of A: at 180˚C for 120 min and B: at 140˚C for 240 min. During refinement, peroxide value (PV) significantly decreased from 7.66 meq/kg in crude oil to 0.5 in deodorized oil A and to 0.21 in deodorized oil B (p < 0.05). Significant reduction in free fatty acids (FFA) was recorded from 0.86% oleic acid in crude oil to 0.15% in deodorized oil A and to 0.33% in deodorized oil B (p < 0.05). N-3 fatty acids content and fatty acids composition were determined by GC-FID and n-3 fatty acids content increased from 18.74% in crude oil to 21.58% in deodorized oil A and to 21.75% in deodorized oil B. The red color in oil significantly decreased from 5.4 to 0.4 and 0.5 in deodorized oil A and deodorized oil B, respectively (p < 0.05). Results confirm that refinement steps improved oil quality and raised n-3 PUFA concentration and n-3/n-6, properly. Deodorization at 180˚C for 120 minutes (A) was more effective than deodorization at 140˚C for 240 minutes (B) in removing off flavors.