The Effect of Slow and Quick Freezing on Fatty Acid and Total Count of Nile Tilapia (Oreochromis niloticus) Fillets

This study is designed to investigate the effects of slow and quick freezing on fatty acids and microbial load of Oreochromis niloticus. Fillets were prepared in groups of slow and quick freezed and were preserved in -18ᵒ centigrade for six months. Changes in Fatty acids amounts and microbial load were monitored every month. Our results indicate statistically significant changes in fatty acid amounts during cold-room preservation in all tested samples. Fresh fillets of O.niloticus contain 24.84 percent of sutured fatty acids (SFAs), 36.14 percent of mono unsutured fatty acids (MUFAs) and 38.62 percent of poly un-sutured fatty acids (PUFAs). However, in the last month of sampling, SFA and MUFA levels significantly increased; whereas PUFA level decreased (p<0.05). In slow and quick freezed O.niloticus, SFA increased to 28.90% and 27.38%, MUFA reached 39.55% and 38.21%, and PUFA decreased to 30.56% and 35.22%, respetively. Changes in fatty acid levels were significantly less severe in fillets with quick freezing method (p<0.05). The results of total count indicate that quick freezed samples had lower numbers of microbial load in comparison with slow ones (p<0.05).