CHEMICAL, PHYSICAL, AND FUNCTIONAL-PROPERTIES OF COD PROTEINS MODIFIED BY A NONENZYMIC FREE-RADICAL-GENERATING SYSTEM

Chelated ferric iron, hydrogen peroxide, and ascorbate were used to ge nerate hydroxyl radical in washed, minced cod muscle. Protein carbonyl content increased between 2 and 24 h of storage at 5 degrees C on tre atment with the free-radical-generating system (FRGS); it increased le ss if that storage period included a freeze/thaw process. There was an equal loss of sulfhydryl groups on treatment with the FRGS for 2 or 2 4 h with or without a freeze/thaw treatment. Electrophoretic results s uggested disulfide formation. Treatment with the FRGS and a freeze/tha w process decreased protein solubility; a combination of the two was s ynergistic. Washed, minced cod muscle had improved gelation and emulsi fication characteristics when treated with the FRGS if the muscle tiss ue was not frozen but had poorer qualities if it was frozen. A model i s proposed to explain the improvement of gelation and emulsification p roperties on exposure to the FRGS as well as its loss when exposed to a freeze/thaw process.