Effect of inoculation (pre- vs. post-grinding) of black pepper on decimal reduction time of Salmonella spp. and Enterococcus faecium NRRL B-2354

Abstract

The laboratory inoculation techniques should ideally mimic the real-life environment to reliably estimate the decimal reduction time (D-value) of bacteria for process validation. This study aims at investigating the influence of the inoculation method on the D-value of Salmonella in black pepper powder. Whole black peppercorns were either inoculated prior to grinding (pre-grinding procedure) or ground and then inoculated (post-grinding procedure). The ground black pepper was thermaly treated at 80°C for 0-30 min. The D80°C values of Salmonella inoculated by pre-grinding and post-grinding procedures were 5.5 ± 0.8 and 3.9± 0.3, respectively. Salmonella and E. faecium were significantly (p⟨0.05) more thermally resistant in ground black pepper when inoculated pre- rather than post-grinding. Therefore, inoculation protocol must be considered by spice industries while validating the pasteurization process. E. faecium is a suitable surrogate for Salmonella because of its higher decimal reduction time for both inoculation methods.