Evaluation of antioxidant properties of Chlorella vulgaris and Spirulina platensis and their application in order to extend the shelf life of rainbow trout (Oncorhynchus mykiss) fillets during refrigerated storage

Fish is a valuable source of protein and contains high amounts of ω-3 polyunsaturated fatty acids (PUFAs) which play an important role in a healthy diet (Avadi & Freon, 2015). Generally, due to the high amounts of free amino acids, volatile basic nitrogen and PUFAs in fish, they are more perishable compared to red meat and poultry meat (Hoel, Jakobsen, & Vadstein, 2017). Fat oxidation is one of the most important reasons for food quality deterioration which leads to changes in color, taste, nutrional value and shelf life of food (Pike & O'Keefe, 2017). Oxidation of PUFAs causes off-flavour and rancid taste due to the for-mation of aldehydes and ketones, reduces the nutrional value by de-struction of essential fatty acids, lipid soluble vitamins and has adverse effects on human health due to the formation of free radicals (Ikape & Cheikyula, 2017; Miyashita, Uemura, & Hosokawa, 2018). Anti-oxidants, when present at lower concentrations than the substance, prolong or inhibit oxidation of oxidizable substances (Kasote, Katyare, Hegde, & Bae, 2015). The ability to generate a new radical after scavenging the radical that is stable within intramolecular hydrogen bonding is another property of a compound to be considered an anti-oxidant (Carocho & Ferreira, 2013). Synthetic antioxidants are mainly phenolic compounds from which BHT, BHA, TBHQ and PG are most commonly used in food industry (Pelle & Compagnone, 2018).

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