Mild Heating Process and Antioxidant Incorporation Increase Quality and Oxidation Stability of Oil from Skipjack Tuna (Katsuwonus pelamis) Eyeball

Oil from skipjack tuna eyeballs is produced by wet rendering method under mild conditions (70-90 degrees C for 30-60 min). Suitable condition (70 degrees C for 30 min) provides the oil having yield of 13.95% and acceptable color (L* = 92.26, a* = -2.17, and b* = 22.37) along with less hydrolytic and oxidative deteriorations. To increase oxidative stability, lecithin (200 and 400 ppm), alpha-tocopherol (200 and 400 ppm), and their combination (1:1 ratio) at the same concentrations are added in the oil and stored for 30 d at 30 degrees C. Oil added with alpha-tocopherol at 400 ppm shows the highest stability within the first 2 d (peroxide value = 339.28 mEq peroxide kg(-1), anisidine value = 34.15, thiobarbituric acid reactive substances = 0.74 mg of MDA kg(-1) of oil). However, at day 30, oil incorporated with alpha-tocopherol at 400 ppm shows no differences in n-3 fatty acids, particularly eicosapentaenoic acid and docosahexaenoic acid from the control. Also, no significant differences in FTIR spectral intensity between both samples at day 30 at wavenumbers 3013 and 1743 cm(-1), representing cis-double bond and carbonyl group, respectively, are observed. Therefore, other appropriate techniques, e.g., packaging or additives are still required for enhancement of oxidative stability of oil from skipjack tuna eyeball.

Automated summary

Oil from skipjack tuna eyeballs is produced by wet rendering method under mild conditions, with suitable conditions providing oil of acceptable color and yield. Addition of alpha-tocopherol can increase oxidative stability of the oil, although other techniques may still be required for further enhancement.