Survival of Unstressed and Acid-, Cold-, and Starvation-Stress-Adapted Listeria monocytogenes in Ham Extract with Hops Beta Acids and Consumer Acceptability of HBA on Ready-to-Eat Ham

Abstract EN

The efficacy of hops beta acids (HBA) against unstressed and stress-adapted Listeria monocytogenes in ham extract and the consumers’ acceptability of HBA on ready-to-eat (RTE) hams were investigated.

Unstressed or acid-, cold-, or starvation-stress-adapted L.

monocytogenes was inoculated (1.3–1.5 log CFU/mL) into 10% ham extract, without (control) or with HBA (4.44 or 10.0 µg/mL).

Survival/growth of the pathogen during storage (7.2°C, 26 days) was monitored periodically.

Sensory evaluation (30 participants, 9-point hedonic scale) was performed with hams dipped into 0.05, 0.11, and 0.23% HBA solution.

Ham extracts without HBA supported rapid growth of unstressed and stress-adapted cells with growth rates of 0.39–0.71 log CFU/mL/day and lag phases of 0–3.26 days.

HBA inhibited growth of unstressed L.

monocytogenes by slowing ( P < 0.05 ) growth rate (0.24–0.29 log CFU/mL/day) and increasing ( P < 0.05 ) length of the lag phase (3.49–12.98 days) compared to control.

Acid-, cold-, or starvation-stress-adapted cells showed cross protection against HBA with greater ( P < 0.05 ) growth rates (0.44–0.66 log CFU/mL/day) and similar or shorter lag phases (0–5.44 days) than unstressed cells.

HBA did not ( P > 0.05 ) affect sensory attributes of RTE ham.

These results are useful for RTE meat processors to develop operational protocols using HBA to control L.

monocytogenes.