At MIC concentration, the pathogen cells were lysed. The C. perfringens cell counts were higher in the control samples during the entire storage period. The mortadella food model used in experiment was an excellent medium for growth of C. perfringens because it presented a wide nutritional

spectrum, with considerable amounts of carbohydrates, minimal required moisture (Aw) and protein content providing all the essential Palbociclib purchase amino acids necessary for growth. In addition, factors including storage temperature and atmosphere packaging (reduced oxygen tensions) contributed to the population growth in the control samples. The effect of the EO on the target microorganism was considerably reduced when applied in the food model (compared to in vitro studies). The application of EOs for the control of pathogens and spoilage bacteria requires the evaluation of their effectiveness in food products or models that roughly simulate the composition of foods. Generally, the efficiency of some additives and natural antimicrobial agents can be reduced by certain components of foods. If higher concentrations of EO are generally required when added to food to maintain product

safety, undesirable flavor and sensory selleckchem changes may occur ( Gutierrez et al., 2008 and Gutierrez et al., 2009). Researchers who have evaluated the effect of EO added to meat reported undesirable sensory changes caused by EO treatment in food samples ( Skandamis and Nychas, 2001, Hayouni et al., 2008 and Govaris et al., 2010). Mortadella has a large amount of fat and protein in its proximate composition, and it is assumed that high levels of fat or protein in food may protect the bacteria from the action of EOs. The EO dissolved in the lipid phase of the food is relatively less available for action on bacteria present in the aqueous phase (Mejlholm and Dalgaard, 2002). The antimicrobial activity of EOs was found to be more pronounced in low-fat foods when compared to high-fat products (Tassou et al., 1995, Singh et al., 2003 and Cava et al., 2007). The

protein content appears to inhibit the antimicrobial effect of EO’s (Smith-Palmer et al., 2001, Vrinda Menon and Thiamine-diphosphate kinase Garg, 2001, Hao et al., 1998 and Pol et al., 2001). Food carbohydrates protect bacteria from the EO action to a lesser extent than fat and protein (Skandamis and Nychas, 2000). Gutierrez et al. (2008) evaluated the interference of food constituents (lipids, carbohydrates and proteins) on antibacterial activity of thyme and oregano EOs on L. monocytogenes, and they suggest that potato starch and lipid oils at concentrations higher than 5% reduce the antilisterial effect. The physical structure of the food model may affect the EO antimicrobial effect. After the cooking process, mortadella has a semisolid physical structure that may impact the distribution of oil and impair its antimicrobial effect. Skandamis et al.