The concentrations of ascorbate, glutathione, $\alpha$-tocopherol, ubiquinone-10, and ubiquinol-10 and their rates of loss in the light and dark muscle of Atlantic mackerel were determined. This was done for the purpose of determining their usefulness as indices of postmortem age and shelf-life quality. A paired fillet technique was used on groups of six fish, freezing one fillet immediately at ${-}62\sp\circ$C as a time "0" control and storing the other on ice for 0.5, 1, 2, 4, 7, or 10.7 days, and then freezing it at ${-}62\sp\circ$C until assayed. Sensory evaluations and determination of thiobarbituric acid-reactive substances (TBARS) were done on the same fish at the same storage times used for antioxidant determinations. All of the antioxidants tested were lost more rapidly in the dark muscle than in the light muscle. In dark muscle, ubiquinol-10 and glutathione were lost most rapidly, followed by ascorbate, which was lost approximately twice as fast as $\alpha$-tocopherol, which in turn was lost two to three times faster than ubiquinone-10. In light muscle, ascorbate and glutathione were lost at approximately the same rate, which was twice as fast as for $\alpha$-tocopherol which was again twice as fast as ubiquinone-10. The low concentration of ubiquinol-10 in light muscle decreased very slowly. Ascorbate, glutathione, and $\alpha$-tocopherol could be used as indices of freshness for the early changes in sensory quality in light muscle, while all of the antioxidants were early indicators of sensory change in dark muscle. Odors indicative of rancidity were detected by the fourth day of storage in dark muscle and the seventh day in light. Polynomial equations were derived to describe the relationship of sensory scores and antioxidant loss in light and dark muscle. The effect of time of frozen storage was determined by comparing time "0" fillets stored for up to 62 days at ${-}62\sp\circ$C. Ascorbate and glutathione decreased significantly (p $<$ 0.01) in light muscle while glutathione decreased and ubiquinol-10 increased significantly (p $<$ 0.01) in dark muscle between the first and fifth days of frozen storage. Ubiquinone-10 demonstrated antioxidant activity in a model system containing 2,2$\sp\prime$-azobis(2,4-dimethylvaleronitrile) (AMVN).
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-2798 |
| Date | 01 January 1996 |
| Creators | Petillo, David |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
Page generated in 0.0023 seconds