title: The effect of homogenization of whole milk, skim milk and milk fat on nisin activity against Listeria innocua.
abstract: Whole milk, skim milk and an emulsion of milk fat in water, inoculated with approx. 10(5) cfu/ml of Listeria innocua, were treated at 30 degrees C with 100 IU/ml of nisin, homogenization at 200 bar or both procedures. Nisin activity and survival of L. innocua after treatments were determined. Recovery of nisin activity from non-homogenized whole milk treated with 100 IU/ml of nisin was complete, whereas a loss of 18 to 28% of activity was detected in non-homogenized fat-in-water emulsion. Loss in nisin activity due to homogenization represented up to 64% in whole milk and 62% in fat-in-water emulsion. Nisin addition by itself achieved a reduction in L. innocua counts of 3.7-3.8 log units in whole milk and 3.6 log units in fat-in-water emulsion compared to numbers in untreated samples. When nisin-containing whole milk and fat-in-water emulsion were homogenized, L. innocua counts were only reduced by 2.6-2.9 log units and 2.5 log units, respectively, compared to numbers in untreated samples. Homogenization of nisin-containing skim milk resulted in a loss of nisin activity of 20% but achieved a reduction of 3.0 log units in L. innocua counts.
authors.affiliation: Departamento de Tecnologia de Alimentos, INIA, Madrid, Spain.
authors.forename: P
authors.initials: P
authors.lastname: Zapico
authors.forename: M
authors.initials: M
authors.lastname: de Paz
authors.forename: M
authors.initials: M
authors.lastname: Medina
authors.forename: M
authors.initials: M
authors.lastname: Nuñez
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004655:Emulsions; D005223:Fats / Q000737:chemistry; D005516:Food Microbiology; D008087:Listeria / Q000187:drug effects / Q000254:growth & development*; D008088:Listeriosis / Q000517:prevention & control; D008892:Milk / Q000737:chemistry / Q000382:microbiology*; D009561:Nisin / Q000494:pharmacology*; D011312:Pressure; D012044:Regression Analysis
chemical_list: D000900:Anti-Bacterial Agents; D004655:Emulsions; D005223:Fats; D009561:Nisin