Evaluation of Occasional Nonresponse of a Washed Cod Mince Model to Hemoglobin (Hb)-Mediated Oxidation
Journal article, 2007
An emerging model to test antioxidants for application in seafoods is washed cod mince fortified with
hemoglobin (Hb) as a catalyst. This system has been used to test the antioxidative activity of certain
muscle extracts and some pure compounds such as BHA, BHT, TBHQ, and propyl gallate during ice
storage. However, the washed cod mince model has occasionally been resistant to Hb-mediated
oxidation. This has been in cases when the moisture of the model has been minimized by washes
at the protein isoelectric point (pH 5.5) to allow for large additions of potentially antioxidative solutions.
In this paper, noncontrollable and controllable factors for this intriguing occasional oxidation resistance
were studied. Compositional analyses (lipid content, alpha-tocopherol, and lipid hydroperoxides) and
structural analysis of a “normal” oxidizing model and a stable model were done to identify any
differences among them. Some controllable factors related to the model preparation that were studied
included different washing pH values (5.5-6.6), Hb concentrations (7.2 and 13.5 íM), final model
moisture contents (75, 81, and 90%), and light exposure during ice storage (0 h, 3-4 h, or 24 h of
light/day). Results revealed a 2-fold higher alpha-tocopherol content in the stable model than in the
oxidizing model. Electron microscopy images showed a more and less disrupted myofibrillar structure
in the stable and the oxidizing cod model, respectively. This indicated that “cold setting” (i.e., pregelation)
of the stable model may have occurred and prevented Hb from diffusing freely in the model.
Controllable factors that reduced lipid oxidation in the models were less Hb and lower moisture.
cod mince model