Fate of Listeria monocytogenes and Aeromonas hydrophila on Catfish Fillets Cooked in a Microwave Oven

Abstract

Channel catfish fillets were inoculated with SJ lo6 cell/cm* each of Listeria monocytogenes and Aeromonas hydrophila and cooked in a microwave oven to internal temperatures of 55, 60, and 70 "C. The fillets were either left uncovered or covered with polyvinylidene chloride films during cooking. A. hydrophila populations were reduced lo nondetectable levels on covered fillets cooked to 70 "C. At 60 "C, L. monocyrogenes populatoins were reduced by = 4 logs for covered and by 2 logs for uncovered fillets. Covering fillets increased lethality at each temperature; however, some pathogens could survive at c 60 "C.

Listeria monocytogenes in Vacuum‐Packed Smoked Fish Products: Occurrence, Routes of Contamination, and Potential Intervention Measures

“…Most of the studies using MW‐heating were performed on food ingredients other than fish products and catfish fillets were the only fish samples that have been used in monitoring the impact of MW‐heating on pathogens so far. Huang and others () demonstrated the use of MW‐heating in fillet samples initially containing 10 6 cell/cm 2 of L. monocytogenes . Covered (polyvinylidene) and uncovered samples that reached an internal temperature of 60 °C during cooking achieved 4 and 2 log reductions, respectively.…”

Survival of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella spp. on Catfish Fillets Exposed to Microwave Heating in a Continuous Mode

“…MW heating utilizes electromagnetic energies at frequencies of 915 or 2450 MHz to generate heat in food materials (Decareau and Peterson 1986; Metaxas and Meredith 1988). Theoretically, MW can penetrate foods and produce volumetrically distributed heating effects, resulting from the molecular friction of water within foods (Oliveira and Franca 2002); therefore, it has been used as a heating source to eliminate microorganisms in foods (Holyoak and others 1993; Huang and others 1993; Gundavarapu and others 1995; Heddleson and others 1996). Guan and others (2003) demonstrated the feasibility of using a 915‐MHz pilot‐scale MW heating system to inactivate Clostridium sporogenes (PA 3679, NFPA NO.…”

“…The FDA (2011) has updated the general MW application concerns and identified 5 research needs, which include “monitoring and real‐time adjusting for process deviations in MW processing.” The major concern with using MW technology for food safety applications is the survival of microorganisms, especially foodborne pathogens, due to uneven heating, including surface cooling effects (FDA 2011) which is well known in food systems. Huang and others (1993) reported the survival of L. monocytogenes and Aeromonas hydrophila in catfish where L. monocytogenes may be reduced by 4 or 2 log‐cycles with fillets covered or uncovered by polyvinylidene chloride film, respectively. Jamshidi and others (2010) reported that E. coli O157:H7 can be largely reduced (>4 log CFU/cm 2 ) on beef slices (200 g), with a 30‐s exposure to 850 W MW heating.…”

Effect of microwave cooking on foodborne pathogens in fish

“…It was seen that, cooking to an internal temperature of 50°C is not sufficient for safety. Incomplete inactivation of L. monocytogenes on catfish fillets has also been reported at <60°C (Huang, Leung, Harrison, & Gates, 1993). For chicken and beef, 6-log reduction of Listeria monocytoges was reported when the temperature of the slowest heating point was 70°C (Gaze, Browng, Gaskelld, & Banks, 1989).…”