Protein oxidation in frankfurters with increasing levels of added rosemary essential oil: Effect on color and texture deterioration

The development of protein oxidation as assessed by the total carbonyl content and its influence on color and texture deterioration during the refrigerated storage (+4 degrees C/60 d) of frankfurters, were studied. The effect of the addition of a rosemary essential oil at different levels (150, 300, and 600 ppm) on the protein oxidative stability of the frankfurters was also evaluated. Frankfurters with no added essential oil were used as controls. The amount of carbonyls from protein oxidation significantly increased during refrigerated storage, and this increase was significantly higher in control frankfurters than in those treated with 300 and 600 ppm. Rosemary essential oil at levels of 300 and 600 ppm successfully protected the I erne molecule from degradation and significantly inhibited the increase of nonheme iron (NHI) in refrigerated stored frankfurters. Color changes were directly related to oxidation processes because frankfurters with added antioxidants (300 and 600 ppm) suffered less color modifications than the controls. The addition of rosemary essential oil enhanced texture characteristics of frankfurters by reducing hardness, adhesiveness, gumminess, chewiness, and controlling the lost of elasticity during refrigeration. Statistically significant correlations were calculated between protein oxidation and instrumentally measured parameters, suggesting that the alteration of protein functionality caused by oxidation likely affected color and texture characteristics of frankfurters.