| Summary: | <i>Pseudomonas fragi</i> is the dominant spoilage organism in various foods, especially in spoiled milk, fish, and meats. Its growth can be inhibited by releasing allyl isothiocyanate (AITC) from ground mustard seeds in food packages. This paper aims to investigate the antimicrobial potential of ground mustard seeds against <i>P. fragi</i> growth and the effectiveness of released AITC concentration from mustard seeds on microbial inhibition of the spoilage bacteria growing in the liquid medium. The AITC concentration in the headspace and the liquid medium was measured and the growth of <i>P. fragi</i> in the liquid medium was monitored. Depending on the concentration of AITC, not only growth was inhibited but a reduction of the total count of <i>P. fragi</i> was even observed. The inactivation rate (k) of <i>P. fragi</i> was estimated using first-order inactivation kinetics and the minimum gaseous-released AITC to inactivate <i>P. fragi</i> was determined. Higher AITC concentration in the headspace and liquid medium was observed when using a higher amount of ground mustard seeds and a lower food to headspace ratio. Increasing the amount of ground mustard seeds (>100 mg per 10 mL liquid medium) led to full inactivation of <i>P. fragi</i> in 48 hours. By using an inhibition sigmoid E<sub>max</sub> model, the minimum gaseous-released AITC for inactivation of <i>P. fragi</i> in 48 hours was observed around 15 µg/l headspace. These results indicate that inhibition of the spoilage bacteria and extending the shelf life using ground mustard seeds is only possible by applying a careful design of the packaging system.
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