MICROBIOLOGICAL, CHEMICAL AND SENSORY ASSESSMENT OF AREOLATED GROUPER (Epinephelus areolatus) FILLETS STORED UNDER MODIFIED

Fresh fish fillets (Epinephelus areola tus) of economical importance were
packed in different modified atmospheres; 80% CO2 + 20% N2: 80% CC2 + 10% 02+
10% N2 and 60% CO2 + 20% 02+ 20% N2. Control samples were packed ¡n air. To
determine the microbiological, chemical and sensory qualities of fish fillets during
storage in different atmospheres at 5°C. Results revealed that total viable count;
Enterobactenaceae; lactic acid bacteria and H2S-producing bacteria were inhibited by
modified atmospheres as compared with the fillets packed in air (control).The
differences were significant (P<0.05).The highest inhibition were observed with
packaging fish fillets in 80% CO2 + 20% N2 and 80% CO2 + 10% 02+ 10% N2 . No
significant differences were observed between samples packed ¡n 80% CO2 + 10%
02+ l0% N2 and samples packed ¡n 80% CO2 + 20% N2 with respect to
microbiological quality. There was significant difference (P<0.05) in pH values
between samples packed in modified atmospheres and samples packed in air
(control). This mainly due to the production of carbonic acid by the dissolved C02 in
the aqueous phase of the fish fillets. Total volatile bases nitrogen (TVB-N) values
were also significantly (P<0.05) decreased by packaging fish fillets in modified
atmospheres after 3 and 6 days of storage at 5°C as compared with the samples
packed in air (control). The sensory evaluation of fish fillets revealed that colour of fish
fillets was improved by packaging in 80°/o 002 + 10% 02+ 10% N2 and 60% CO2 +
20% 02+ 20% N2. In contrast the colour of samples packed in 80% CO2 + 20% N2
was evaluated as poor after 3 days of storage. However the, colour of samples
packed in air were still acceptable after 6 days of storage. The 80% CO2 + 10% 02+
10% N2 gas mixture was the most effective for the colour stability of the fish fillets. The
changes ¡ri odour followed closely the changes in bacterial counts. Microbiological and
chemical changes supported the sensory results. Fish fillets packed in 60% CO2 +
20% 02+ 20% N2; 80% CO2 + 20% N2 and 80% CO2 + 10% 02 10% N2 have a shelf
life at 5°C of 10, 12 and 12 days respectively. This signifies a prolongation of shelf life
at 5°C of 4, 6 and 6 days respectively, as compared with samples packed in air
(control). The best results were obtained by packaging fish fillets in 80% 002 + 10%
02+ 10°h N2.Packaging Areolated grouper (Epinephelus areoiatts) fillets in 80% CO2 + 10%
02+ 10% N2 will improve the microbiological, chemical and sensory quality and
prolong shelf life of the fish during storage at 5°C.