Gram-Negative Bacteria in Refrigerated Catfish Fillets Treated with Lactic Culture and Lactic Acid ^†

Catfish fillets were treated with combinations of lactic culture ( Lactococcus lactis spp. cremoris ATCC 19257) and lactic acid using a meat tumbler. Fillets were placed individually in Ziploc bags and stored at 4 or 10°C. Counts of gram-negative bacteria on crystal violet tetrazolium chloride agar (CVT), the pH, and the sensory quality of fillets were evaluated after 0, 3, 6, and 9 days of storage time. The combination of 2.5% lactic culture and either 2% lactic acid dip (5 min) or 3% lactic acid dip (1 or 5 min) effectively (P < 0.05) inhibited counts for 9 days. The most effective treatment combination was 2.5% lactic culture incubated for 48 h and 3% lactic acid dip. The pH of samples treated with lactic culture and lactic acid ranged from 5.6 to 6.1 for 9 days at 4 or 10°C Lactic culture and lactic acid combinations extended the refrigerated shelf life of catfish for an additional 3 days at 4 and 10°C and reduced CVT counts by two log cycles over untreated fish. The combination of lactic culture and lactic acid were generally preferred for flavor and odor compared to controls after 6 and 9 days of storage, respectively.