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Potential for Development of Tolerance by Penicillium digitatum and Penicillium italicum after Repeated Exposure to

L L Schroeder1, L B Bullerman

  • 1Department of Food Science and Technology, University of Nebraska-Lincoln, Lincoln, Nebraska 68583-0919.

Applied and Environmental Microbiology
|October 1, 1985
PubMed

Insights

Sorbic acid and potassium sorbate effectively inhibit mold growth, with minimal development of tolerance observed in Penicillium strains. Mold inhibition depends on pH, exposure time, and compound concentration.

Area of Science:

  • Food Science
  • Microbiology
  • Mycology

Background:

  • Penicillium species are common post-harvest molds affecting fruits.
  • Sorbic acid and potassium sorbate are widely used food preservatives.
  • Understanding mold tolerance to preservatives is crucial for food safety.

Purpose of the Study:

  • To determine the minimum inhibitory concentrations (MICs) of sorbic acid and potassium sorbate against Penicillium digitatum and Penicillium italicum.
  • To investigate the potential for increased tolerance to these compounds in selected mold strains.

Main Methods:

  • Determination of MICs for sorbic acid and potassium sorbate against two Penicillium species.
  • Repeated exposure of mold strains to subinhibitory levels of preservatives to assess tolerance development.
  • Evaluation of fungicidal/fungistatic activity based on pH, exposure time, and concentration.

Main Results:

  • MIC of sorbic acid for P. digitatum was 0.02-0.025% at pH 4.75.
  • MIC of potassium sorbate for P. digitatum and P. italicum was 0.06-0.08% at pH 5.5.
  • No significant increased tolerance to sorbic acid was observed in P. digitatum.
  • P. italicum showed slight increased tolerance to potassium sorbate, while P. digitatum did not.
  • Inhibitor activity was dependent on pH, exposure time, sorbate level, and mold strain.

Conclusions:

  • Sorbic acid and potassium sorbate demonstrate effective antimicrobial activity against Penicillium molds.
  • Development of significant tolerance to these preservatives is limited in the tested strains.
  • The efficacy of sorbate as a mold inhibitor is influenced by environmental factors and microbial genetics.

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