F. Shahidi et al., OXIDATIVE STABILITY OF OIL FROM BLUBBER OF HARP SEAL (PHOCA-GROENLANDICA) AS ASSESSED BY NMR AND STANDARD PROCEDURES, Food research international, 27(6), 1994, pp. 555-562
Oils from seal blubber and cod liver were extracted, refined and bleac
hed in a laboratory scale process. Oxidative stability of oils was eva
luated over a 16-day period under accelerated oxidation conditions at
65 degrees C. Peroxide value (PV), contents of conjugated dienes (CD)
and trienes (CT), 2-thiobarbituric acid reactive substances (TBARS) an
d p-anisidine values (AnV) were determined. In addition, NMR spectrosc
opy was used to monitor relative changes in the proton pattern of the
fatty acids of oils during storage. Cod liver oil showed higher PV, CD
, CT and TBARS values as compared with seal blubber oil. The ratio of
aliphatic to olefinic protons in both oils determined by NMR spectrosc
opy increased steadily over the entire length of the storage period, i
ndicating progressive oxidation of unsaturated fatty acids in both oil
s. A significant correlation (P less than or equal to 0.05) was found
between these ratios and TOTOX values (2PV + AnV) for both oils, thus
suggesting that NMR methodology can be used as an effective means to s
imultaneously estimate both primary and secondary oxidation changes.