title: Effects of nisin, EDTA and salts of organic acids on Listeria monocytogenes, Salmonella and native microflora on fresh vacuum packaged shrimps stored at 4 °C.
abstract: Nisin (500 IU ml⁻¹), EDTA (0.02 M), potassium sorbate (PS) (3%, w/v), sodium benzoate (SB) (3%, w/v) or sodium diacetate (SD) (3%, w/v); alone or in combination were used to dip uninoculated shrimps and shrimps inoculated with Listeria monocytogenes or Salmonella (∼4.0-5.0 log CFU g⁻¹). Shrimps were then drip-dried, vacuum packaged and stored at 4 °C for 7 days. Untreated shrimps were used as a control. Numbers of L. monocytogenes, Salmonella and native background microflora were determined on uninoculated and inoculated shrimps on days 0, 3 and 7. Nisin-EDTA-PS and nisin-EDTA-SD significantly reduced (p < 0.05) L. monocytogenes numbers by 1.07-1.27 and 1.32-1.36 log CFU g⁻¹, respectively, on day 0 and 3. However, all treatments failed to significantly reduce (p > 0.05) Salmonella counts on shrimps throughout storage. On day 7, numbers of aerobic bacteria, psychrotrophic bacteria and Pseudomonas on combined nisin-EDTA-salt of organic acids treated shrimps were significantly lower (p < 0.05) by 4.40-4.60, 3.50-4.01, and 3.84-3.99 log CFU g⁻¹ respectively, as compared to the control. Dipping in organic acids solutions followed by vacuum packaging and chilled storage can help reduce L. monocytogenes and native microflora, but not Salmonella, on fresh shrimps.
authors.affiliation: School of Agricultural and Food Sciences, University of Queensland, St. Lucia, Queensland 4072, Australia.
authors.forename: M N
authors.initials: MN
authors.lastname: Wan Norhana
authors.forename: Susan E
authors.initials: SE
authors.lastname: Poole
authors.forename: Hilton C
authors.initials: HC
authors.lastname: Deeth
authors.forename: Gary A
authors.initials: GA
authors.lastname: Dykes
mesh_terms: D000818:Animals; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004492:Edetic Acid / Q000032:analysis; D005506:Food Contamination / Q000032:analysis; D005516:Food Microbiology; D018857:Food Packaging; D005520:Food Preservatives / Q000032:analysis*; D061353:Food Storage / Q000379:methods; D008089:Listeria monocytogenes / Q000187:drug effects* / Q000254:growth & development; D009561:Nisin / Q000032:analysis; D033561:Penaeidae / Q000382:microbiology*; D012034:Refrigeration; D012475:Salmonella / Q000187:drug effects* / Q000254:growth & development; D012492:Salts / Q000032:analysis; D017747:Seafood / Q000032:analysis / Q000382:microbiology*; D013011:Sorbic Acid / Q000032:analysis; D014618:Vacuum
chemical_list: D005520:Food Preservatives; D012492:Salts; D009561:Nisin; D004492:Edetic Acid; D013011:Sorbic Acid