Microbial changes on freshly slaughtered pork carcasses due to "hot" lactic acid decontamination

• Published in: Journal of food safety Vol. 17; no. 2; pp. 89 - 111
• Main Authors: Netten, P. van, Mossel, D.A.A, Huis in't Veld, J.H.J
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-09-1997; Blackwell
• Subjects: ACIDE LACTIQUE; ACIDO LACTICO; ANTIBACTERIAL PROPERTIES; ANTIMICROBIAL PROPERTIES; BACTERIA; Biological and medical sciences; CANAL ANIMAL; CARCASSE; CARCASSES; CARNE DE CERDO; DESINTOXICACION; DETOXIFICATION; ELECTROSTATIC SPRAYING; Food industries; Fundamental and applied biological sciences. Psychology; HIGIENE DE LA CARNE; HYGIENE DE LA VIANDE; LACTIC ACID; Meat and meat product industries; MEAT HYGIENE; MESOPHILIC BACTERIA; MICROORGANISME PSYCHROPHILE; MICROORGANISMOS PSICROFILOS; PORK; PROPIEDADES ANTIMICROBIANAS; PROPRIETE ANTIMICROBIENNE; PSYCHROPHILIC MICROORGANISMS; PULVERISATION; PULVERIZACION; SPRAYING; TEMPERATURA; TEMPERATURE; VIANDE PORCINE; Decontamination; Electrostatic spraying; Chemical treatment; Hot spraying; Concentration effect; Meat product; Lactic acid; Antimicrobial agent; Carcass; Pork; Bactericidal effect
• ISSN: 0149-6085; 1745-4565
• DOI: 10.1111/j.1745-4565.1997.tb00179.x

We studied the microbial changes on fresh (still warm) pork carcasses immediately after electrostatic spraying of lactic acid solutions and during chilled storage. Lactic acid decontamination (LAD) included electrostatic spraying of hot (55C) solutions of 1% lactic acid for 90 s and 2%- and 5% lactic acid for 30 and 90 s. The treatments increased the carcass surface temperature from 22C to about 32-43C. The bactericidal activity of lactic acid killed mainly Gram-negative bacteria. Reductions in "total" psychrotrophic Gram-negative and Enterobacteriaceae counts were found reliable indicators for the efficacy of LAD. Hot 2-5% LAD treatments achieved overall reductions in Gram-negative psychrotrophs ranging from 0.8 to more than 1.4 log10 cfu per cm2. Overall reductions in mesophilic Enterobacteriaceae counts ranged from approximately 1.2 to more than 1.8 log10 cfu per cm2. Treatments with 1% lactic acid achieved marginal 0.5-0.6 overall log10 reductions in these groups of organisms. Bactericidal effects after LAD occurred during a lag period of whose duration increased with the lactic acid concentration of the spray solution. The lag lasted less than 1 day on 1% LAD, 2 days on 2% LAD and 4 days on 5% LAD meat. During these lags the meat surface pH rose from pH 2.7 to 3.2 immediately after LAD to ph 4.8 to 5.2. During aerobic chilled storage after LAD the growth of Gram-negative psychrotrophs was controlled only temporarily. These organisms became the dominant group of organisms. The practical utility of electrostatic spraying of fresh pork carcasses with hot 1-5% LAD to improve the keeping quality is questionable