The main purpose of this investigation was to study the effect of immersing fillets of Nile Tilapia (Orechromis niloticus)
in 1% acetic acid and storage under standard conditions (80% CO2: 20% N2) at a temperature of 2°C on their shelf life.
Fillets samples were divided into four groups, Group 1 (G1): the fillets immersed in sterilized distilled water for 2 minutes
and packaged in Polyamide/ Polyethylene (PA/PE) bags. Group 2 (G2): the fillets immersed in sterilized distilled water
and stored under standard conditions. Group 3 (G3): the fillets immersed in 1% acetic acid for 2 minutes and packaged in
PA/PE bags. Group 4 (G4): the fillets immersed in 1% acetic acid and stored under standard conditions. All samples
were stored at a temperature of 2°C for 21 days and analyzed at the beginning of the experiment and after 7, 14 and 21
days of storage. Results of the study showed that the organoleptic properties of tilapia fillets dropped by the extension of
the cold storage time to 21 days. The average values of Thiobarbituric acid-reactive substances (TBARS) in the G1, G2,
G3 and G4 are 9.23, 2.56, 8.07 and 0.98 at day 21 of the cold storage at a temperature of 2 °C, respectively. Tilapia fillets
kept under CO2-enriched atmosphere had lower total volatile base nitrogen (TVB-N) than those stored in air where the
average values were 19.9, 15.93, 18.97, 15.93 mg/100g in G1, G2, G3 and G4, respectively at the end of the storage
period. The results also showed that the total viable count (TVC) remained at permitted in G4 as the average number was
6.14 ± 0.05 × 103 after 21 days of storage at a temperature of 2 °C, while in G1, G2 and G3 were 7.53 ± 0.06 × 106, 7.63
± 0.11 × 105 and 5.30 ± 0.09 × 106 respectively. Thus, the results indicated that the tilapia fillet immersion in 1% acetic
acid and storage under standard conditions that have been applied in our study contributed to the extension of the validity
period for tilapia fillet for a longer period of cold storage of up to 21 days