Foodborne bacterial infections can affect high numbers of people with large-scale outbreaks occurring. There have been a number of outbreaks due to Escherichia coli O157:H7 (EHEC O157). EHEC O157 was first recognized as a human pathogen in 1982 during the investigation of two outbreaks of bloody diarrhoea in Oregon and Michigan (USA) (Riley et al. 1983). Outbreaks of the infections have now been reported from United States and Canada (Bell et al. 1994), Asia (Michino et al. 1998), Australia (Desmarchelier 1996) and Europe (Williams et al. 2000).
One of the biggest problems with controlling EHEC O157 outbreaks is the low infectious dose required for infection to occur (Strachan et al. 2001; Teunis et al. 2004). This means that even slight contamination of surfaces or work areas may cause serious infection. Many vegetable and fruit products such as apple, raspberries and strawberries can be contaminated. Injuries to apples through stem punctures, bird pecks or wounds created when they drop and by other various types of physical abuse may permit entry of pathogens such as EHEC O157 from animal feces, contaminated water, dust or soil (Riordan et al. 2000). Dingman (2000) reported the ability of E. coli O157:H7 to survive and grow in the areas of injury on an apple, and thus, there exists a food safety risk associated with those apples to be consumed raw or destined for the production of unpasteurized apple cider. Recent outbreaks of foodborne illness associated with consumption of fruit juices, in particular apple cider, has led to published regulations by the U.S. Food and Drug Administration (FDA) proposing mandatory adoption of hazard analysis critical control point (HACCP) programs (FDA Food and Drug Administration 1998; Annous et al. 2001). In this way, EHEC O157 presents a serious public health risk from cross-contamination from surfaces to food produce.
Yeasts have been studied for more than two decades as biological control agents against postharvest diseases caused by fungal pathogens of fruit. Wounded fruit, in particular, needs protection because wounds are primary sites of infection by several postharvest fungal pathogens. Cryptococcus laurentii, Pichia guilliermondi, Kloeckera apiculata, Sporobolomyces roseus, Candida sake and Candida oleophila (Usall et al. 20002001; Abadias et al. 2001; Gamagae and Sivakumar 2004; Lassois et al. 2008) have shown biocontrol effectiveness against postharvest diseases caused by fungal pathogens of apple. Recently, inhibition of E. coli and other enterobacteria by Pichia anomala and Hansenula anomala yeast in storage systems has been shown by M. Olstorpe and colleagues (Olstorpe et al., 20102012). There is few scientific literature about application of C. oleophila yeast as antagonist for controlling of EHEC O157 in vegetable or fruit products.
In this study, inactivation kinetics of inoculated EHEC O157 in apple wounds using C. oleophila was studied. The main objective of this research is to investigate the feasibility and effectiveness of C. oleophila for reducing population of EHEC O157.