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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Crop and Commodity Protection Research » Research » Publications at this Location » Publication #393831
Research Project: Postharvest Protection of Tropical Commodities for Improved Market Access and Quarantine Security

Location: Tropical Crop and Commodity Protection Research

Title: Behaviors of Salmonella enterica serovar Typhimurium and Listeria monocytogenes on whole avocado during storage at 21 or 7°C and their reduction by aqueous chlorine dioxide and peroxyacetic acid

Author
item DONG, LIANGER - University Of Hawaii
item Wall, Marisa
item LI, YONG - University Of Hawaii

Submitted to: LWT - Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/19/2022
Publication Date: 12/20/2022
Citation: Dong, L., Wall, M.M., Li, Y. 2022. Behaviors of Salmonella enterica serovar Typhimurium and Listeria monocytogenes on whole avocado during storage at 21 or 7°C and their reduction by aqueous chlorine dioxide and peroxyacetic acid. LWT - Food Science and Technology. 173. Article 114359. https://doi.org/10.1016/j.lwt.2022.114359.
DOI: https://doi.org/10.1016/j.lwt.2022.114359

Interpretive Summary: The microbial safety of avocados was studied following sanitation with chlorine bleach (NaClO), aqueous chlorine dioxide (ClO2), or peroxyacetic acid (PAA) at two storage temperatures. Salmonella Typhimurium and Listeria monocytogenes showed the potential to persist on whole fresh avocados at 7°C and 21°C. Aqueous ClO2 (20 ppm) and PAA (80-100 ppm) were effective sanitizers that could be used in avocado washing as alternatives to NaClO.

Technical Abstract: The microbiological safety of avocado is concerning in light of associated foodborne illness outbreaks and product recalls. There are limited studies regarding the behavior of pathogenic bacteria on this fruit. This study aimed to investigate the fate of Salmonella Typhimurium and Listeria monocytogenes on whole fresh avocados stored at 21 and 7°C, and evaluate the efficacy of chlorine bleach (active compound: NaClO), aqueous chlorine dioxide (ClO2), and peroxyacetic acid (PAA) in reducing the pathogens on whole avocados. Avocados were inoculated with 7 log CFU of the bacteria and bacterial levels were determined on day 0, 1, 4, 7, and 10 at 21°C and day 0, 1, 7, 10, and 14 at 7°C. Avocados inoculated with 8 log CFU of the bacteria were treated with 200 ppm NaClO, 10, 15, and 20 ppm ClO2 produced by mixing sodium chlorite with HCl or malic acid, and 60, 80, and 100 ppm PAA for 5 min followed by determining the residue bacteria on avocados. Populations of S. Typhimurium increased by 0.71 log CFU on day 10 at 21°C and decreased by 0.93 log CFU at 7°C (P < 0.05). L. monocytogenes remained stable around 6.95-7.27 log CFU at 21 and 7°C. For S. Typhimurium, 15 and 20 ppm ClO2 produced with malic acid and 100 ppm PAA reduced all the bacteria from the initial inoculation level to an undetectable level. Twenty ppm ClO2 produced with HCl and 80 ppm PAA reduced the bacteria by 6.42 and 6.57 log CFU, respectively. NaClO inactivated 3.38 log CFU of S. Typhimurium. For L. monocytogenes, 20 ppm ClO2 produced with malic acid showed the highest reduction of 6.93 log CFU. NaClO, 20 ppm ClO2 made with HCl, and 100 ppm PAA reduced L. monocytogenes by 4.27, 4.16, and 5.16 log CFU, respectively. This study indicated the potential growth and survival of pathogenic bacteria on whole avocados. Twenty ppm ClO2 or 80-100 ppm PAA may serve as alternative sanitizers to NaClO in avocado washing.