• Gaseous ozone’s efficacy for microbial inactivation varies by food matrix. • Nearly 5-log CFU/g reductions were achieved on dried basil. • E. faecium was an effective surrogate only for dried basil leaves. • Mild heating further enhanced gaseous ozone’s efficacy for basil and black pepper. • Quality was largely preserved; key changes were volatiles, germination, and oxidation. The rise in Salmonella -related recalls and outbreaks linked to low-moisture foods (LMFs) necessitates the development of effective decontamination processes that do not compromise product quality. The objective of this study was to inactivate Salmonella spp. inoculated onto dried basil leaves, black peppercorns, walnuts, and chia seeds using gaseous ozone (O 3 ) treatments, and to evaluate the surrogate efficacy of Enterococcus faecium NRRL B-2354. Food products were inoculated with cocktails of Salmonella spp. and E. faecium and equilibrated to a water activity of 0.55. Two-gram samples of inoculated foods were treated in a customized chamber with ozone concentrations of 900–930 ppm and a relative humidity (RH) of 90% for 1-5 h, followed by mild heating (MH) at 40 °C for 4 h after the 3-h O 3 treatment. The 5-h O 3 treatment resulted in log reductions of 5.0 ± 0.6 for basil, 2.4 ± 0.2 for black pepper, 1.7 ± 0.3 for walnuts, and 1.1 ± 0.0 for chia seeds. The 3-h O 3 + MH treatment resulted in an additional 0.4–1.8-log reduction in Salmonella , compared with 3-h O 3 alone (p < 0.05), yielding reductions comparable to those of the 5-h O 3 treatment. E. faecium was a suitable surrogate for Salmonella only for dried basil leaves. In terms of quality, neither treatment significantly affected the color or total phenolic content of the four LMFs. Moderate, concentration-dependent reductions in antioxidant activity were observed for basil, black peppercorns, and chia seeds. The 3-h O 3 + MH treatment better preserved chia seed germination, walnut oxidative stability, and black pepper volatile compounds, whereas the 5-h O 3 treatment better maintained basil volatile compounds. The results of this study indicate that the combined effects of ozone, relative humidity, and mild heating can improve the microbial safety of LMFs during storage. However, the food matrix may be a limiting factor.
Khattra et al. (Sun,) studied this question.