title: Antimicrobial treatments to control Listeria monocytogenes in queso fresco.
abstract: Queso fresco, is a Hispanic non-fermented cheese highly susceptible to contamination with L. monocytogenes. This research was aimed to determine the effect of GRAS antimicrobial ingredients to control L. monocytogenes. Antimicrobials included caprylic acid (CA), Nisaplin®(N, 2.5% nisin), a mixture of sodium lactate and sodium diacetate (SL/SD), Lactococcus lactis sbp. lactis DPC 3147, monolaurin, and lactic acid (LA). Batches of queso fresco curds were inoculated with 104CFU/g and stored at 4 °C for three weeks. During storage the count of L. monocytogenes reached 7 to 8 Log CFU/g in control samples. Most individual antimicrobial treatments resulted in less than 1 Log CFU/g reductions in final counts, with the exception of N (0.5 g/kg) and CA (2.9 g/kg) that caused more than 3 and 5 Log CFU/g differences with controls, respectively. Mixtures of ingredients were more effective in inhibiting L. monocytogenes growth, and treatments with N and CA consistently delivered 6 Log CFU/g less counts than controls. Supplementation of 12 g/kg LA to treatments with SL/SD (3%/0.22%) caused differences of more than 4 Log CFU/g in final Listeria populations. Samples treated with the binary mixtures of N and CA (0.5 and 0.7 g/kg, respectively) were evaluated in a consumer panel (n = 67). Panelists slightly preferred control and commercial over treated samples, but all samples were in average rated between "slightly liking" and "moderately liking." These experiments indicated that combined use of antimicrobial ingredients may be an effective way to control the population of Listeria monocytogenes in queso fresco.
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA.
authors.forename: António
authors.initials: A
authors.lastname: Lourenço
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA.
authors.forename: Mary B
authors.initials: MB
authors.lastname: Kamnetz
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA.
authors.forename: Camila
authors.initials: C
authors.lastname: Gadotti
authors.affiliation: Department of Food Science and Nutrition, University of Minnesota, St. Paul, MN 55108, USA. Electronic address: fdiez@uga.edu.
authors.forename: Francisco
authors.initials: F
authors.lastname: Diez-Gonzalez
mesh_terms: D000085:Acetates / Q000494:pharmacology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002210:Caprylates / Q000494:pharmacology; D002611:Cheese / Q000382:microbiology*; D015169:Colony Count, Microbial; D003258:Consumer Behavior; D003257:Consumer Product Safety; D005516:Food Microbiology; D005519:Food Preservation / Q000379:methods; D005520:Food Preservatives / Q000494:pharmacology*; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000254:growth & development*; D009561:Nisin / Q000494:pharmacology; D019354:Sodium Lactate / Q000494:pharmacology; D013649:Taste
chemical_list: D000085:Acetates; D000900:Anti-Bacterial Agents; D002210:Caprylates; D005520:Food Preservatives; D009561:Nisin; C548838:sodium diacetate; C031492:octanoic acid; D019354:Sodium Lactate
keywords: Antimicrobial mixtures; Caprylic acid; Listeria monocytogenes; Nisin; Queso fresco