THE EFFECT OF “GREEN” ANTIOXIDANTS ON LIPID OXIDATION IN DRIED SALMON (Salmo salar) DURING STORAGE CONDITIONS

Nowadays food industries were concentrating on substituting the use of synthetic natural “green” antioxidants. Therefore, the present study focused on lipid oxidations in dried salmon (Salmo salar) with and without natural antioxidants (garlic powder, cinnamon) during different storage conditions, and a comparison was made with a synthetic antioxidant Butylated hydroxytoluene (BHT). Minced salmon fillet mass was divided into four equal parts and each part was treated with natural antioxidant under study except the control. Each of these four parts was dried in two different ways, half portion oven-dried and the other half portion freeze-dried. After 24 weeks, these samples were tested for peroxide value (PV), Thiobarbituric acid reactive substances (TBARS), total carbonyl content/water-soluble protein. According to the peroxide value (PV) results, it was noticed that the BHT was found to be the most effective antioxidant, followed by garlic and cinnamon for oven-dried salmon. Cinnamon was found to be more efficient than garlic in minimizing PV formation in freeze-dried salmon. In general, the initial study showed that freeze-drying was more efficient than oven drying. On the other hand, total carbonyl content for oven-dried salmon treated with cinnamon, garlic, and BHT, was found to be similar to the untreated salmon. Freeze-dried antioxidant treated salmon was generally found to possess more carbonyl content over time compared to the oven dried treated salmon.

Carbonylated Proteins Are Detectable Only in a Degradation-Resistant Aggregate State in Escherichia coli

ABSTRACT Carbonylation is currently used as a marker for irreversible protein oxidative damage. Several studies indicate that carbonylated proteins are more prone to degradation than their nonoxidized counterparts. In this study, we observed that in Escherichia coli, more than 95% of the total carbonyl content consisted of insoluble protein and most were cytosolic proteins. We thereby demonstrate that, in vivo, carbonylated proteins are detectable mainly in an aggregate state. Finally, we show that detectable carbonylated proteins are not degraded in vivo. Here we propose that some carbonylated proteins escape degradation in vivo by forming carbonylated protein aggregates and thus becoming nondegradable. In light of these findings, we provide evidence that the accumulation of nondegradable carbonylated protein presented in an aggregate state contributes to the increases in carbonyl content observed during senescence.