Gaseous chlorine dioxide inactivation of microbial contamination on whole black peppercorns

Authors: RANE, BHARGAVI - Washington State University; Lacombe, Alison; GUAN, JIEWEN - Washington State University; BRIDGES, DAVID - University Of California, Davis; SABLANI, SHYAM - Washington State University; TANG, JUMING - Washington State University; Wu, Vivian

Submitted to: Journal of Food Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2021
Publication Date: 11/10/2021
Citation: Rane, B., Lacombe, A.C., Guan, J., Bridges, D.F., Sablani, S., Tang, J., Wu, V.C. 2021. Gaseous chlorine dioxide inactivation of microbial contamination on whole black peppercorns. Journal of Food Safety. Article e12948. https://doi.org/10.1111/jfs.12948.
DOI: https://doi.org/10.1111/jfs.12948

Interpretive Summary: Whole black peppercorns are grown and harvested internationally under inadequate agricultural and manufacturing practices where they may be exposed to several contaminants such as pathogens, coliforms, and molds during the process. These harmful microorganisms may be considered as a food safety issue, especially when peppercorn is an ingredient added to ready-to-eat foods, thus, decreasing its economic value due to product loss. The current study assessed the initial concentrations of aerobic bacteria, coliforms, yeasts, and molds on imported whole black peppercorns. Additionally, the study investigated the effect of gaseous ClO2 to reduce microbial contamination. High initial microbial contamination was observed on whole black peppercorns. Results demonstrated that ClO2 treatment for 1 h at R.T. (21 ± 2 C) achieved a ~1 log reduction (90%) of aerobic bacteria, coliforms, yeasts, and molds. This study indicated that the high microbial contamination on imported whole black peppercorns requires appropriate sanitation practices. Gaseous ClO2 can be used in the peppercorn industry as a dry and nonthermal treatment to enhance food safety and reduce economic loss.

Technical Abstract: Black peppercorn is a common ingredient imported and used in uncooked or ready-to-eat foods in the U.S. They are exposed to fecal coliforms and other microbial contamination due to a lack of good agricultural and manufacturing practices within some developing countries under which they are grown and harvested. Thus, causing economic losses to the peppercorn industry in the U.S. We investigated the effect of gaseous chlorine dioxide (ClO2) on reducing the microbial population level of coliforms, aerobic bacteria, yeasts, and molds on unprocessed black peppercorns. Treatments on peppercorns were conducted in a 30-L airtight chamber, and equal amounts of dry media precursors were used to generate gaseous ClO2. Whole peppercorns (200 g) were exposed to 20, 30, and 40 g of precursor dose for up to 60 min at 21 ± 0.4 C and in combination with mild heat at 40 ± 2 C. Selective media was used to enumerate the aerobic bacteria, coliforms, yeasts, and molds present on peppercorns. Results demonstrated ~1 log10 reduction (90%) for all the microbes post-treatment at 21 ± 0.4 C. The treatments conducted with a 30g precursor dose for 60 min at 21 ± 0.4 C were statistically higher (P<0.05) than at 40 ± 2 C. Our work demonstrated that gaseous ClO2 could be suitable to reduce the coliforms, aerobes, yeasts, and molds on black peppercorns without affecting its visual quality. It may be used as a part of an overall hurdle technology strategy to reduce microbial loads on peppercorns.