Contents lists available at ScienceDirect International Journal of Food Microbiology journal homepage: www.elsevier.com/locate/ijfoodmicro Control of Salmonella enterica and Listeria monocytogenes in hummus using allyl isothiocyanate Amin N. Olaimat a, ⁎ , Murad A. Al-Holy a , Mahmoud Abu Ghoush a , Anas A. Al-Nabulsi b , Richard A. Holley c a Department of Clinical Nutrition and Dietetics, Faculty of Allied Health Sciences, The Hashemite University, P.O. Box 150459, Zarqa 13115, Jordan b Department of Nutrition and Food Technology, Jordan University of Science and Technology, P.O. Box 3030, Irbid, Jordan c Department of Food and Human Nutritional Sciences, Faculty of Agricultural and Food Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada ARTICLE INFO Keywords: Salmonella Listeria monocytogenes Hummus Allyl isothiocyanate Natural antimicrobials Glucosinolates Shelf-life ABSTRACT Hummus (chickpea dip) is a ready-to-eat product which has been implicated in several foodborne outbreaks and food recalls. This study aimed to screen the antimicrobial activity of allyl isothiocyanate (AITC) against 5 strains of each of Salmonella enterica and Listeria monocytogenes using a disc diffusion method. Additionally, the anti- microbial activity of 0.1–1.5% (v/w) AITC against both pathogens and aerobic bacteria in hummus was also investigated. The inhibition zones of AITC were 8.5–15 and 7.0–8.5 mm against the S. enterica and L. mono- cytogenes strains, respectively, at 37 °C. S. enterica numbers were reduced by > 6 log 10 CFU/g in hummus con- taining ≥0.5% AITC by 3 days at both 4 and 10 °C. While 0.1–0.25% AITC reduced S. enterica by 2.5–5.1 log 10 CFU/g at 4 °C or by 4.7–6.0 log 10 CFU/g at 10 °C by 10 days. Similarly, L. monocytogenes numbers decreased by > 6 log 10 CFU/g in hummus with ≥0.5% or ≥1.0% AITC at 4 or 10 °C, respectively, by 3 days. Further, 0.25% AITC significantly reduced L. monocytogenes in hummus by 2.7 and 4.3 log 10 CFU/g at 4 and 10 °C, respectively. Moreover, 0.1% AITC reduced L. monocytogenes by 1.8 log 10 CFU/g in hummus at 10 °C and in- hibited the growth at 4 °C for up to 10 days. The aerobic bacterial count also significantly decreased in un- inoculated hummus treated with 1.0–1.5% AITC at both 4 and 10 °C, while a concentration of 0.25–0.5% AITC inhibited their growth at 4 °C. AITC can be used to reduce the risk of salmonellosis or listeriosis in hummus and extend its shelf-life. 1. Introduction Chickpeas are an important pulse crop, also known as the species Cicer arietinum L. and are a member of the Leguminosae family (Wallace et al., 2016). Chickpea consumption in the world is represented mainly by the consumption of hummus (chickpea dip) which is made from cooked, mashed chickpeas blended with tahini, lemon juice, olive oil and spices (Yamani and Mehyar, 2011). Hummus is one of the most popular traditional foods in the Middle East countries and it contains a high amount of moisture (71.0%), 14.3% carbohydrates, 7.9% protein, 9.6% fat, 1.7% ash and 6% fiber (Amr and Yaseen, 1994; Wallace et al., 2016). Hummus also provides the consumer with significant amounts of B vitamins and minerals including sodium, potassium, phosphorus, magnesium, calcium, selenium, iron and manganese. Therefore, it is considered that hummus can be a component in a healthy Mediterra- nean-style diet as well as being a desirable item in the 2015–2020 Dietary Guidelines for Americans. These features explain the significant increase in consumption of hummus in western countries in the last decade (Wallace et al., 2016). Hummus is a ready-to-eat product consumed directly without fur- ther processing or additive treatments to achieve safety (Olaimat et al., 2017). However, foodborne pathogens such as Salmonella spp., Listeria monocytogenes, Shigella spp. and Escherichia coli have been isolated from hummus (Almualla et al., 2010; Khiyami et al., 2011; Varma et al., 2007). In the US in 2015, 30,000 containers of hummus were recalled due to contamination with L. monocytogenes (FDA, 2015). Further, the largest reported outbreak in the US, which involved 802 illnesses in 2007 was caused by hummus contaminated with Salmonella (CDC, 2010). A subsequent Salmonella outbreak in the US involving 16 cases was also associated with hummus (CDC, 2013). Recently, the consumer demand for natural antimicrobials to re- place artificial preservatives has increased. Few studies have in- vestigated the effect of natural antimicrobials against foodborne pa- thogens in hummus (Al-Holy et al., 2006; Alali et al., 2012; Olaimat https://doi.org/10.1016/j.ijfoodmicro.2018.04.033 Received 26 October 2017; Received in revised form 18 April 2018; Accepted 19 April 2018 ⁎ Corresponding author at: Department of Clinical Nutrition and Dietetics, Faculty of Allied Health Sciences, The Hashemite University, P.O. Box 150459, Zarqa 13115, Jordan E-mail address: aminolaimat@hu.edu.jo (A.N. Olaimat). International Journal of Food Microbiology 278 (2018) 73–80 Available online 21 April 2018 0168-1605/ © 2018 Elsevier B.V. All rights reserved. T