Influences of Bleeding Conditions on the Quality and Lipid Degradation of Cobia (Rachycentron canadum) Fillets During Frozen Storage
2018
Nguyen, Minh Van | Thi Phan, Le My
The effects of bleeding methods (iced water bleeding and air bleeding) on the quality and lipid degradation of cobia fillets during frozen storage for 24 weeks at -20 2 C were investigated. Bleeding significantly retarded lipid hydrolysis and oxidation progress, resulting in lower free fatty acid (FFA), lipid hydroperoxides (PV), thiobarbituric acid-reactive substances (TBARS) and higher phospholipids content (PL) obtained in bled samples. A higher polyunsaturated fatty acid (PUFA) content was observed in the bled samples compared to that of the unbled samples. Ice water bleeding showed the best bleeding method in terms of blood removal, leading to lower heme and non-heme iron contents in the fish muscle. Heme pigments in the fish muscle oxidised during frozen storage, resulting in decreased heme iron content and increased non-heme iron content. The development of lipid hydrolysis and oxidation was in high correlations with the heme and non-heme iron content remained in the fish muscle. Oxidation of lipid and heme pigments was the main cause of the flesh discolouration during frozen storage, resulting in decreased lightness (L* value) and increased yellowish (b* value). Cobia need to be bled before processing to maintain the quality of the product during frozen storage.
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