Inactivation of <em>E</em>. <em>faecium</em> NRRL B-2354 in Whole Black Pepper by Fluidization with Hydrogen Peroxide Vapor

This study evaluated Enterococcus faecium NRRL B-2354 as a surrogate for Salmonella inactivation in black peppercorns treated with hydrogen peroxide (HP) vapor via fluidization. The selected parameter for dwell temperature was 60ºC for 60 minutes. The reduction of both Salmonella and E. faecium, along with changes in water activity, color, and residual hydrogen peroxide, were measured before, immediately after treatment and at 24 and 48 hours post-treatment. Results showed that E. faecium exhibited a significantly greater reduction (4.63 ± 0.55 log CFU/g) compared to Salmonella (2.94 ± 0.16 log CFU/g) (p < 0.05), making E. faecium unsuitable as a surrogate for Salmonella in these conditions. Treatment led to a significant decrease in water activity and moisture content (p < 0.05). Color changes were perceptible to the naked eye, as indicated by a ΔE > 3. Storage time did not significantly affect water activity and moisture content (p > 0.05). Residual hydrogen peroxide reached up to 350 ppm immediately post-treatment and showed a decreasing trend over storage time. These findings suggest that while HP vapor treatment can reduce microbial populations in black peppercorns, E. faecium NRRL B2354 is not an appropriate surrogate for Salmonella under these specific conditions, and further optimization of the process is needed to enhance microbial inactivation and minimize quality loss. Advisor: Rossana Villa Rojas