Effectiveness of current hygiene practices on minimization of Listeria monocytogenes in different mushroom production‐related environments

Abstract

Background The commercial production of Agaricus bisporus is a three stage process: 1) production of compost, also called “substrate”; 2) production of casing soil; and 3) production of the mushrooms. Hygiene practices are undertaken at each stage: pasteurization of the substrate, hygiene practices applied during the production of casing soil, postharvest steam cookout, and disinfection at the mushroom production facilities. However, despite these measures, foodborne pathogens, including Listeria monocytogenes, are reported in the mushroom production environment. In this work, the presence of L. monocytogenes was evaluated before and after the application of hygiene practices at each stage of mushroom production with swabs, samples of substrate, casing, and spent mushroom growing substrates. Results L. monocytogenes was not detected in any casing or substrate sample by enumeration according to BS EN ISO 11290‐2:1998. Analysis of the substrate showed that L. monocytogenes was absent in 10 Phase II samples following pasteurization, but was then present in 40% of 10 Phase III samples. At the casing production facility, 31% of 59 samples were positive. Hygiene improvements were applied, and after four sampling occasions, 22% of 37 samples were positive, but no statistically significant difference was observed ( p > .05). At mushroom production facilities, the steam cookout process inactivated L. monocytogenes in the spent growth substrate, but 13% of 15 floor swabs at Company 1 and 19% of 16 floor swabs at Company 2, taken after disinfection, were positive. Conclusion These results showed the possibility of L. monocytogenes recontamination of Phase III substrate, cross‐contamination at the casing production stage and possible survival after postharvest hygiene practices at the mushroom growing facilities. This information will support the development of targeted measures to minimize L. monocytogenes in the mushroom industry.

Multinational Outbreak of Listeria monocytogenes Infections Linked to Enoki Mushrooms Imported from the Republic of Korea 2016–2020

“…A study by Dygico et al (2020) showed that isolates of L. monocytogenes can form high levels of biofilm on surfaces of materials commonly found in the mushroom industry. L. monocytogenes may be entering mushroom production operations through incoming raw materials, such as improperly handled spawn or inadequately pasteurized growing substrate, and survive and grow in production and packing house environments when there are insufficient hygiene practices ( Pennone et al, 2020 ; Yuk et al, 2007 ) and possible cross-contamination occurring due to insanitary practices ( Dygico et al, 2020 )). L. monocytogenes could also survive on the surface of mushrooms during storage and at retail ( Viswanath et al, 2013 ).…”

Persistence of microbiological hazards in food and feed production and processing environments

“…The incorporation of two simple chiller heating protocols into these facilities' GMPs effectively reduced Listeria prevalence in chillers. Steam cookout of the floors of mushroom growing units can minimise the chances of contamination of subsequent batches, as shown by Pennone et al (2020). Tobin et al (2020) illustrated the feasibility of hot water disinfection treatments of commercial mushroom slicers to minimise L. monocytogenes food safety risks.…”

“…pathways of the manufacturing area to the maximum extent practicable (Ortiz et al, 2014); the use of various chemical interventions (Malley et al, 2013), the implementation of one or a combination of hygienic measures (Murugesan et al, 2015) or the simultaneous implementation of various corrective actions (Pennone et al, 2020;Strydom et al, 2016).…”

“…Relevant studies describing actions triggered by persistence with the aim to eliminate persistent L. monocytogenes from the processing environment are shown in Table 5. Actions included the introduction of new or specialised (deep) C&D (of more difficult to clean equipment) (Biguzzi et al., 2012; Blatter et al., 2010; Stessl et al., 2020); the implementation of workflows (Dalmasso & Jordan, 2013); the installation of a new drainage system with back‐flow prevention (Jordan et al., 2012); the implementation of structural changes and renovations (Nakari et al., 2014); the control of the contamination of raw ingredients and the improvement of the compartmentalisation (Ortiz et al., 2010); the reduction of all contamination pathways of the manufacturing area to the maximum extent practicable (Ortiz et al., 2014); the use of various chemical interventions (Malley et al., 2013), the implementation of one or a combination of hygienic measures (Murugesan et al., 2015) or the simultaneous implementation of various corrective actions (Pennone et al., 2020; Strydom et al., 2016).…”

Genetic Characterization of Listeria from Food of Non-Animal Origin Products and from Producing and Processing Companies in Bavaria, Germany

“…In order to assess the risk of exposure to L. monocytogenes from FNAO, the occurrence and further characteristics, such as genotype and serotype detection, antimicrobial resistances (AMR), and virulence markers of the pathogen in FNAO products and primary production and processing plants, needs to be investigated. Up to now, only a few studies examined the presence and further characteristics of L. monocytogenes in different areas of FNAO production and processing companies [ 16 , 17 , 18 ]. In addition, the more isolates from agricultural environments, FNAO fresh produce, and RTE food and processing environments that are collected and characterized, the greater the understanding of foodborne-associated outbreaks related to L. monocytogenes [ 19 ].…”