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The Klunzinger's ponyfish (Equulites klunzingeri) protein powder extracted with acid or alkali aided process as a biodegradable coating material for rainbow trout (Oncorhynchus mykiss) fillets during cold (+2 • C) and frozen storage (-18 • C) were investigated. The coating with alkaline treated protein (AlPC) and acid treated protein (AcPC) extended the shelf life of fillets from 11 to 14 days in cold storage and improved the quality parameters in three months frozen storage period. According to total viable count and total psychrophile count results, bacteria grew more quickly in uncoated fillets than coated fillets. The protein-based coating did prevent spoilage of the rainbow trout fillets as reflected by a decrease in pH, total volatile base-nitrogen and free fatty acids during cold and frozen storage period. Therefore, this study demonstrated that fish protein-based coating had a positive effect on maintaining the rainbow trout fillets quality, and edible coatings from discard fish can offer a promising alternative for preserving fish fillets.

Summary Lipid quality and fatty acid compositions of fish oils recovered from fish (Sea bass – Dicentrarchus labrax) waste silages produced with formic acid (FA) and five different LAB strains (Lactobacillus plantarum (LP), Pediococcus acidilactici (PA), Enterococcus gallinarum (EG), Lactobacillus brevis (LB) and Streptococcus spp. (ST)) were assessed to ensure for the usage for human consumption. Generally, it was observed that there were no significant differences between PUFA contents (23.27–23.64%). Peroxide (PV) (2.12 meq active O2/per kg of oil) and TBA values (1.07 mg malonaldehyde (MA) g−1 oil) of fish oils from acid silage were significantly higher than those of the fermented ones (1.14–1.91 meq active O2 kg−1, 0.67–0.81 mgMA g−1 oil, respectively). Anisidine values (AV) were determined in range of 8.04–11.14 for fermented silages and 13.08 from acid silage. The highest totox value (17.33 ± 0.88) was also detected in acid silage oil whereas fermented groups gave totox value in the range of 10.40–13.88. It can be concluded that the initial lipid quality of fermented fish waste silages was better than the initial lipid quality of acid fish waste silage. Therefore, fish oils recovered from fermented silages can be used as food additives or supplements for animal and human diets.

The effects of rosemary extract addition on oxidative stability of cooked sea bream during frozen storage period were investigated. Sea bream fillets were fried, oven baked and grilled. Three groups with rosemary extract were also cooked by the same methods and cooked samples (with and without rosemary extract) were stored in -18°C for 4 months. After cooking procedures, the FFA formation was quite similar in fresh-raw and fried sea bream fillets, but significantly increased oven baked (0.31-0.33% oleic acid) and grilled fillets (0.39-0.40% oleic acid). The highest value of PV was also obtained from grilled fillets (1.18-1.58 meq/kg). However, TBA values (1.92 mg MA/kg for fresh-raw fillet) did not increase in sea bream fillets after the frying and grilling procedure except oven baking without rosemary extract (2.41 mg MA/kg). A considerable increase in the FFA, PV and TBA was observed in all cooked groups during frozen storage period. The treated samples with rosemary extract generally showed slower PV and TBA formation than those of the untreated samples. However, the additions of rosemary extract have positive effect on sensory quality of baked sea bream.