Effectiveness of daily rinsing of alfalfa sprouts with aqueous chlorine dioxide and ozonated water on the growth of Listeria monocytogenes during sprouting

Abstract

Alfalfa sprouts have been implicated in multiple foodborne disease outbreaks. This study evaluated the growth of Listeria monocytogenes during sprouting of alfalfa seeds and the effectiveness of daily chlorine dioxide & ozone rinsing in controlling the growth. Alfalfa seeds inoculated with L. monocytogenes were sprouted for 5 days (25°C) with a daily aqueous ClO2 (3 ppm, 10 min) or ozone water (2 ppm, 5 min) rinse. Neither treatment significantly reduced the growth of L. monocytogenes on sprouting alfalfa seeds. The initial level of L. monocytogenes was 3·44 ± 0·27, which increased to c. 7·0 log CFU per g following 3 days of sprouting. There was no significant difference in the bacterial population between the treatment schemes. Bacterial distribution in roots (7·63 ± 0·511 log CFU per g), stems (7·51 ± 0·511 log CFU per g) and leaves (7·41 ± 0·511 log CFU per g) were similar after 5 days. Spent sanitizers had significantly lower levels of bacterial populations compared to the spent distilled water control. The results indicated that sprouting process provides a favourable condition for the growth of L. monocytogenes and the sanitizer treatment alone may not be able to reduce food safety risks. Significance and Impact of the Study Sprouts are high‐risk foods. Consumption of raw sprouts is frequently associated with foodborne disease outbreaks. Optimum sprouting procedure involves soaking seeds in water followed by daily water rinsing to maintain a moist environment that is also favourable for the growth of pathogenic micro‐organisms. The present study emphasized the potential food safety risks during sprouting and the effect of applying daily sanitizer rinsing in the place of water rinsing to reduce those risks. The finding of this study may be useful in the development of pre‐harvest and post‐harvest risk management strategies.

Effectiveness of Aqueous Chlorine Dioxide in Minimizing Food Safety Risk Associated with Salmonella, E. coli O157:H7, and Listeria monocytogenes on Sweet Potatoes

“…Sodium chlorite solution (450 mL of 10 μg/μL) was mixed with 1N hydrochloric acid (21 mL) in a 1000 mL PYREX ® storage bottle and stored for 1 h at room temperature with continuous stirring [ 28 , 29 ]. The final working concentration of 5 ppm was prepared by diluting the stock solution with distilled water.…”

Plants as a realized niche for Listeria monocytogenes

“… a Data on the ability of Lm to colonize plants under laboratory conditions is available with the following plant species: parsley ( Petroselinum crispum ) (Bardsley et al, 2019; Kljujev et al, 2018), lettuce ( Lactuca sativa ) (Chitarra, Decastelli, et al, 2014; Honjoh et al, 2018; Jablasone et al, 2005; Kljujev et al, 2018; Shenoy et al, 2017; Standing et al, 2013), corn salad ( Vallerianella locusta ) (Chitarra, Decastelli, et al, 2014; Hofmann et al, 2014), spinach ( Spinacia oleracea ) (Hofmann et al, 2014; Jablasone et al, 2005; Kljujev et al, 2018), mustard spinach ( Brassica rapa ) (Koseki, Mizuno, Yamamoto, 2011), cultivated rocket ( Eruca sativa ) (Chitarra, Decastelli, et al, 2014; Settanni et al, 2012), wild rocket ( Diplotaxis tenuifolia ) (Chitarra, Decastelli, et al, 2014), cress ( Lepidium sativum ) (Jablasone et al, 2005), carrot ( Daucus carota ) (Kljujev et al, 2018), radish ( Raphanus raphanistrum ) (Jablasone et al, 2005), sweet pepper ( Capsicum annuum ) (Füstös et al, 2017), basil ( Ocimum basilicum ) (Bardsley et al, 2019; Chitarra, Decastelli, et al, 2014; Settanni et al, 2012), cilantro ( Coriandrum sativum ), dill ( Anethum graveolens ) (Bardsley et al, 2019), tomato ( Solanum lycopersicum ) (Honjoh et al, 2016), cantaloupe ( Cucumis melo ) (Nyarko et al, 2016), peach ( Prunus persica ), plum ( Prunus domestica ) (Collignon & Korsten, 2010), sweet corn ( Zea mays ) (Kljujev et al, 2018), alfalfa sprouts ( Medicago sativa ) (Adhikari et al, 2019), pigeon pea ( Cajanus cajan ) (Sharma et al, 2020), Arabidopsis ( Arabidopsis thaliana ) (Milillo et al, 2008), and Fescue grass ( Festuca arundinacea ) (Marinho et al, 2020; Sharma et al, 2020). The table presents major findings only when more than one paper is available for a given plant species.…”

Industrial Hemp (Cannabis sativa L.) Varieties and Seed Pre-Treatments Affect Seed Germination and Early Growth of Seedlings

“…Chlorine dioxide (ClO 2 ), a chlorine-based disinfectant, is known for its fungicidal, bactericidal and viricidal properties and is effective in decontaminating seeds and sprouts from a wide range of microorganisms and human pathogens [22][23][24]. However, the effect of ClO 2 on seed germination and seedling growth of industrial hemp has not been studied so far but has recently been explored in other crops, including vegetables [23], cucurbits [24] and barley [26].…”

“…Seed germination and early seedling growth depend on several factors, including varieties with different seed sizes [10][11][12], seed sources [13][14][15] and seed origins [16,17]. They also respond differently to pre-treatments with chemicals, such as plant growth regulators [18][19][20], seed disinfectants [21][22][23][24][25][26][27][28] and cold temperatures [29][30][31][32][33].…”