Development of a Microbial Population within a Hot‐Drinks Vending Machine and the Microbial Load of Vended Hot Chocolate Drink

Abstract

In order to understand the development of the microbial population within a hot-drinks vending machine a new machine was placed in a staff area of a university campus vending only hot chocolate. The machine was cleaned weekly using a detergent based protocol. Samples from the mixing bowl, dispense area, and drink were taken over a 19-wk period and enumerated using plate count agar. Bacillus cereus was identified using biochemical methods. Vended drinks were sampled at 0, 3, 6, and 9 min after vending; the hot chocolate powder was also sampled. Over the 1st 8 wk, a significant increase in the microbial load of the machine components was observed. By the end of the study, levels within the vended drink had also increased significantly. Inactivation of the automatic flush over a subsequent 5-wk period led to a statistically but not operationally significant increase in the microbial load of the dispense area and vended drink. The simple weekly clean had a significant impact on the microbial load of the machine components and the vended drink. This study demonstrated that a weekly, detergent-based cleaning protocol was sufficient to maintain the microbial population of the mixing bowl and dispense point in a quasi-steady state below 3.5 log CFU/cm2 ensuring that the microbial load of the vended drinks was maintained below 3.4 log CFU/mL. The microbial load of the drinks showed no significant changes over 9 min after vending, suggesting only spores are present in the final product.

Automatic Vending-Machines Contamination: A Pilot Study

“…There has been one published case of bacterial food poisoning from a hot-drinks vending machine. Nelms (Nelms et al, 1997) reported on a case of food poisoning (Bacillus Cereus) in a Minneapolis manufacturing plant, where employees reported vomiting and nausea after drinking hot chocolate from a vending machine based in the plant cafeteria (Hall et al, 2007). In Italy the provision of food and beverages through This system identifies the risks for human health and the safety and preventive measures for their elimination and/or their control (Dragoni & Bonomi, 2008).…”

“…In Italy the provision of food and beverages through This system identifies the risks for human health and the safety and preventive measures for their elimination and/or their control (Dragoni & Bonomi, 2008). Kassa et al (2001) also stated the importance of direct visual inspection, as another measure for preventing potential risk of food-borne illnesses (Hall et al, 2007;Kassa, Harrington, Bisesi, & Khuder, 2001). As mentioned above, previous studies focused on hygiene and contamination of the internal mechanical parts of the vending machines, on the microbiological quality of the powders used to prepare the beverages, and/or on the beverages direct contamination (Hall et al, 2007;Nelms et al, 1997;Vallone & Bonomi, 2013).…”

“…Kassa et al (2001) also stated the importance of direct visual inspection, as another measure for preventing potential risk of food-borne illnesses (Hall et al, 2007;Kassa, Harrington, Bisesi, & Khuder, 2001). As mentioned above, previous studies focused on hygiene and contamination of the internal mechanical parts of the vending machines, on the microbiological quality of the powders used to prepare the beverages, and/or on the beverages direct contamination (Hall et al, 2007;Nelms et al, 1997;Vallone & Bonomi, 2013). The main purpose of our study was rather to highlight whether a microbial population on the critical surfaces may contaminate the beverages; therefore, we wanted to assess whether there can be a potential risk for consumer's health, considering that cross-contamination is involved in many food-borne outbreaks (Rossvoll et al, 2015).…”

“…Previous studies (Hall, Short, Saltmarsh, Fielding, & Peters, 2007;Nelms, Larson, & Barnes-Josiah, 1997) were focused on assessing the contamination of coffee powders and/or beverages, without considering if and how the surfaces in direct contact both with beverages and/or with cups/glasses might be contaminated as well.…”

Profiling Bacillus cereus populations in a traditional style, hot-drinks vending machine and vended hot chocolate drink using polymerase chain reaction (PCR) and random amplified polymorphic DNA (RAPD) techniques

“…Bacillus cereus has been isolated from cocoa, hot chocolate powder and vended hot chocolate drinks (Chung-Wang, Kuo, Lin, Hong, & Tsai, 1993;Gabis, Langlois, & Rudnick, 1970;Hall, Short, Saltmarsh, Fielding, & Peters, 2007;Nelms, Larson, & Barnes-Josiah, 1997). Cocoa and hot chocolate powders have also been found to contain other Bacillus sp., Staphylococcus aureus, yeasts and moulds (ChungWang et al, 1993;Gabis et al, 1970;Payne et al, 1983).…”