Escherichia coli O157:H7 and Salmonella Typhimurium inactivation by the effect of mandarin, lemon, and orange by-products in reference medium and in oat-fruit juice mixed beverage

The antimicrobial capability of three water extracts of citrus peels was evaluated against Salmonella enterica serovar Typhimurium and Escherichia coli O157:H7 at various concentrations (0.5, 1, 5, 10%) and temperatures (5, 10, 22 °C) in a reference medium. The best of them was mandarin by-product, achieving a maximum inactivation level against S. Typhimurium (8 log10 cycles) with 5% at 5 °C. Also, this by-product had the highest total polyphenol content. Mandarin by-product showed a bactericidal effect in a food matrix also at 5 °C (≈2 log10 cycles). All results were adjusted to the Weibull model and the b values indicated that the higher concentration of mandarin, the greater the inactivation rate in reference medium, without significant differences between 5 and 10%. Similarly, in the food matrix, the inactivation rate of S. Typhimurium was higher when the mandarin by-product was added. Therefore, the mandarin by-product could be used as a control measure of S. Typhimurium in pasteurized products, which are stored under refrigeration.M. Sanz-Puig is grateful to the CSIC for providing a contract as a researcher working actively on the projects with reference IPT-2011-1724-060000 and AGL 2013–48993-C2-2-R, funded by the Ministry of Economy and Competitiveness and with FEDER funds. M.C. Pina-Pérez is grateful to the CSIC for providing a doctoral contract.Peer reviewe