Antioxidant effect of ascorbic acid on the quality of Cobia (Rachycentron canadum) fillets during frozen storage



effect of aqueous solutions of ascorbic acid (AA) on the rancidity development
in Cobia (Rachycentron canadum) fillets during frozen storage was
studied. Cobia fillets were treated with ascorbic acid (AA 0.25% and AA 0.5%)
then stored at -18°C up to 6 months. Rancidity
development was measured by several biochemical indices including free fatty
acids (FFA), peroxide value (PV), and thiobarbituric acid (TBA) and complemented by the sensory analysis ( odor,  consistency and  appearance). In addition, pH and
expressible moisture (EM) were measured during 6 months storage. Proximate composition
was also determined in the first day. TBA, PV and
FFA levels increased on all treatments due to lipid oxidation. Ascorbic acid
showed antioxidative effect on Cobia fillets during frozen storage as indicated
by TBA, PV and FFA levels. Results showed that free fatty acid, primary
and secondary oxidation products,  EM and
pH value of AA- treated samples were significantly lower than those of the
control samples (P < 0.05). A gradual decrease (P < 0.05)
in sensory analysis were observed as the storage
time increased. Results of our investigation revealed that ascorbic acid
retarded oxidative changes in frozen Cobia fillets whereas AA 0.25% was not as
effective as AA 0.5% on oxidative stability. Best oxidation inhibition results
on fish fillets were obtained when employing a 0.5% AA solution.