Antilisterial effects of different hop acids in combination with potassium acetate and potassium diacetate at 7 and 37 °C

Cell Envelope Modifications Generating Resistance to Hop Beta Acids and Collateral Sensitivity to Cationic Antimicrobials in Listeria monocytogenes

“…Kramer et al studied a commercial HBA extract similar to the one used in our work and reported MIC values for L. monocytogenes DSM15675 of 12.5 ppm at pH 7.2 and 1.6 ppm at pH 5.0 after 18 h incubation at 37 °C in Mueller–Hinton broth [ 23 ]. Another study reported an MIC of 6.3 ppm for HBA in Trypticase Soy Broth–Yeast Extract against a cocktail of L. monocytogenes strains after 24 h at 37 °C [ 57 ]. Larson et al tested the inhibitory effect of several hop extracts again L. monocytogenes Scott A and reported growth inhibition for 1 ppm of an extract containing about 30% colupulone, 65% lupulone, and adlupulone in BHI at 37 °C for 43 h [ 58 ].…”

“…Although HBA and other hop extracts are generally considered to have a bacteriostatic effect, some researchers have reported a bactericidal effect against L. monocytogenes [ 24 , 57 ]. In our study, no inactivation of the WT and any of the mutant strains was observed upon a 3 h challenge with high concentrations of HBA (up to 64 ppm) in a buffer at pH 7.…”

Effect of Hops Beta Acids on the Survival of Unstressed‐ or Acid‐Stress‐Adapted‐Listeria Monocytogenes and on the Quality and Sensory Attributes of Commercially Cured Ham Slices

“…There is a growing tendency for consumers to purchase RTE meat products containing natural antimicrobials to control foodborne pathogens to protect their long‐term health (Shen and others ; Sansawat and others ). Consequently, hops extract, along with other extracts such as cloves, rosemary, grape seed, cherry powder, lime powder, and cranberry have been actively evaluated for antimicrobial activity in bacterial broth and on meat products (Shen and others ; Sansawat and others ). Currently, 4 different natural plant‐based antimicrobials, including rosemary extract, lemon extract, grape‐fruit extract, and hops beta acids (HBA), have been approved by the USDA‐FSIS for use in RTE meat products as ingredients or on product surfaces (USDA‐FSIS ).…”