A combination of high-voltage atmospheric cold plasma and cinnamaldehyde significantly increases inactivation of Salmonella enterica and Escherichia coli O157:H7 in raw pineapple juice

Abstract

The main objective of this study was to determine the antibacterial effectiveness of high voltage atmospheric cold plasma (HVACP) alone or combined with cinnamaldehyde against S. enterica and E. coli O157:H7 in raw pineapple juice. Additional objectives were to evaluate sublethal injury in pathogen survivors and physicochemical properties of the juice. Juice with or without added cinnamaldehyde (100 μL/L) and inoculated with ∼7.0 log₁₀ CFU/mL of S. enterica or E. coli O157:H7, was exposed to HVACP (70 kV, 60 Hz) for 0 (control), 1.0, 3.0, 5.0, and 7.0 min. HVACP or cinnamaldehyde alone failed to achieve a 5.0-log₁₀ CFU/mL reduction of the pathogens. In contrast, reductions (log₁₀ CFU/mL) from combined application of HVACP and cinnamaldehyde were 5.38 (S. enterica) and 5.60 (E. coli O157:H7) after 7.0 min (P < 0.05) with significant sublethal injury in S. enterica survivors (P < 0.05). The degrees Brix increased only in HVACP-treated juice without cinnamaldehyde (P < 0.05). HVACP treatment for 3 or 7 min, decreased lightness but increased chroma of the juice (P < 0.05); however, color differences were not visually detectable. The combined use of HVACP and cinnamaldehyde can enhance the microbial safety of pineapple juice with minimal changes in the physiochemical properties evaluated in this study.