The female flower of the hop plant, Humulus lupulus, is known for its antimicrobial properties and has long been used as an important preservative and flavoring agent of beer. The antimicrobial aspects of hops are primarily attributed to the alpha acids (humulones) and beta acids (lupulones). These acids are also responsible for imparting a bitter flavor to the flower. Active mostly against only Gram-positive bacteria,
the mechanism of humulone and lupulone bactericidal ability is by disruption of the cell membrane (De Keukeleire, 2000; Simpson & Smith, 1992; Teuber and Schmealreck, 1973). The FSIS has approved the inclusion of beta acids as antimicrobials for cooked meat and in casings for ready-to-eat (RTE) meat products;
however, there are few published studies on the use of these hop-components in poultry products. Shen, Geornaras, Kendall, and Sofos (2009) reported the use of beta acids to eliminate L. monocytogenes from the surface of frankfurters. Frankfurters inoculated with L. monocytogenes were dipped in aqueous solutions of beta acids at several concentrations, vacuum packaged, and stored under refrigeration.
Levels of L. monocytogenes were reduced by1.3–1.6 log CFU after initial dip (compared to 1 log reduction in control dip). Lag-phase was lengthened and growth rates were suppressed during storage. More research is required to determine the efficacy of beta acids on other products as well as the effect of such treatments on sensory qualities.
