There is a plethora of scientific evidence that consuming
long-chain polyunsaturated fatty acids from marine fish oils has
beneficial health effects. However, fish oils also contain antioxidants.
Unfortunately, there has been limited research on the antioxidant
activity of these oils.
USDA-ARS scientists evaluated the antioxidant activity of oils
extracted from pink salmon heads and viscera with varying degrees of
freshness and which had been stored at two temperatures. They determined
that thiobarbituric acid reactive substances (TBARS) values in the raw
material are good predictors of antioxidant activity in the extracted
fish oil.
In experiments, pink salmon heads and viscera were collected by the
scientists from a commercial processing plant in Kodiak, AK. The heads
and viscera were mixed together and aged at 6 C and 15 C for four days.
The researchers removed the samples from both treatments on days 0, 1,
2, 3 and 4. Then they extracted the oil for analysis. The raw samples
were analyzed for volatile amines and TBARS. Using a
photochemiluminescence detection technique, the oil samples were
analyzed for lipid soluble antioxidant activity.
The investigators found that there was a decrease in the
antioxidant activity of the extracted oils during the four days of
storage. No significant difference in the regression lines between the
two storage temperatures was observed. The antioxidant activity of the
pink salmon oils at day 0 and day 4 at 15 C was 0.89[+ or -]0.15 mmole
Torlox equivalence per L of oil and 0.41[+ or -]0.12 mmole Torlox
equivalence per L of oil, respectively.
An analysis of the raw samples suggested that the TBARS were better
indicators than volatile amines for determining the antioxidant activity
in the extracted oils with a high correlation coefficient. Storage
temperatures of 6 C or 15 C were of less importance than storage times
for reducing the antioxidant activity in the extracted fish oil.
Further information. Ted H. Wu, USDA-ARS Subarctic Agricultural
Research Unit, 229 O'Neill Building, University of
Alaska-Fairbanks, Fairbanks, AK 99775; phone: 907-474-5011; fax:
907-474-1813; email: ftthw@uaf.edu.
COPYRIGHT 2008 Food Technology Intelligence,
Inc. Reproduced with permission of the copyright holder. Further reproduction or distribution is prohibited without permission.
Copyright 2008 Gale, Cengage Learning. All rights
reserved. Gale Group is a Thomson Corporation Company.
NOTE: All illustrations and photos have been removed from this article.