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

Abstract

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.