Evaluation of sanitizers for inactivating Salmonella on in-shell pecans and pecan nutmeats

J Food Prot. 2012 Nov;75(11):1930-8. doi: 10.4315/0362-028X.JFP-12-133.

Abstract

Chlorine, organic acids, and water extracts of inedible pecan components were tested for effectiveness in killing Salmonella on pecans. In-shell pecans and nutmeats (U.S. Department of Agriculture medium pieces) were immersion inoculated with a mixture of five Salmonella serotypes, dried to 3.7% moisture, and stored at 4°C for 3 to 6 weeks. In-shell nuts were immersed in chlorinated water (200, 400, and 1,000 μg/ml), lactic acid (0.5, 1, and 2%), and levulinic acid (0.5, 1, and 2%) with and without 0.05% sodium dodecyl sulfate (SDS), and a mixed peroxyacid sanitizer (Tsunami 200, 40 μg/ml) for up to 20 min at 21°C. The rate of reduction of free chlorine in conditioning water decreased as the ratio of in-shell nuts/water was increased. The rate of reduction was more rapid when nuts were not precleaned before treatment. The initial population of Salmonella on in-shell nuts (5.9 to 6.3 log CFU/g) was reduced by 2.8 log CFU/g after treating with chlorinated water (1,000 μg/ml). Treatment with 2% lactic acid plus SDS or 2% levulinic acid plus SDS reduced the pathogen by 3.7 and 3.4 log CFU/g, respectively. Lactic and levulinic acids (2%) without SDS were less effective (3.3- and 2.1-log CFU/g reductions, respectively) than acids with SDS. Treatment with Tsunami 200 resulted in a 2.4-log CFU/g reduction. In-shell nuts and nutmeats were immersed in water extracts of ground pecan shucks (hulls), shells, a mixture of shells and pith, and pith. The general order of lethality of extracts to Salmonella was shuck < shell-pith ≤ shell ≤ pith < chlorine (400 μg/ml) and shuck < shell ≤ pith = shell-pith < chlorine (400 μg/ml). Results emphasize the importance of removing soil and dust on in-shell pecans before conditioning in chlorinated water and the need for sanitizers with increased effectiveness in killing Salmonella on pecans.

Publication types

  • Evaluation Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Anti-Infective Agents / pharmacology*
  • Carya / microbiology*
  • Chlorine / pharmacology
  • Colony Count, Microbial
  • Consumer Product Safety
  • Dose-Response Relationship, Drug
  • Food Contamination / analysis
  • Food Contamination / prevention & control*
  • Food Handling / methods*
  • Food Microbiology
  • Humans
  • Lactic Acid / pharmacology
  • Levulinic Acids / pharmacology
  • Salmonella / drug effects*
  • Salmonella / growth & development
  • Salmonella Food Poisoning / prevention & control
  • Sanitation
  • Sodium Dodecyl Sulfate / pharmacology
  • Time Factors

Substances

  • Anti-Infective Agents
  • Levulinic Acids
  • Lactic Acid
  • Sodium Dodecyl Sulfate
  • Chlorine
  • levulinic acid