New insights in thermal resistance of staphylococcal strains belonging to the species Staphylococcus epidermidis, Staphylococcus lugdunensis and Staphylococcus aureus. (April 2015)

• Record Type: Journal Article
• Authors: Montanari, Chiara; Serrazanetti, Diana I.; Felis, Giovanna; Torriani, Sandra; Tabanelli, Giulia; Lanciotti, Rosalba; Gardini, Fausto
• Is Part Of: Food control. Volume 50(2015:Apr.)
• Page Start: 605
• Page End: 612
• Publication Date: 2015-04
• Subjects: Staphylococci -- Thermal resistance -- Carvacrol -- Citral -- Stress response; Food -- Quality -- Periodicals; Food -- Analysis -- Periodicals; Food handling -- Periodicals; Food industry and trade -- Quality control -- Periodicals; Aliments -- Industrie et commerce -- Qualité -- Contrôle -- Périodiques; Aliments -- Qualité -- Périodiques; Aliments -- Analyse -- Périodiques; Hygiène alimentaire -- Périodiques; Food -- Analysis; Food handling; Food -- Quality; Periodicals; Electronic journals; 664.07
• DOI: 10.1016/j.foodcont.2014.09.039
• Languages: English
• ISSNs: 0956-7135

Abstract

Abstract: In this study the thermal resistance of seven strains of staphylococci was studied. Three of them (two Staphylococcus epidermidis and one Staphylococcus lugdunensis ) were isolated from pasteurized tofu, while one Staphylococcus aureus from fermented sausages. Also the corresponding type strains were tested. Their heat resistance was assessed at 80 °C also in relation to different growth conditions (high NaCl concentrations and low pH). Moreover, the effect of two terpenes (carvacrol and citral) on their survival during thermal treatment was assessed. All the strains were able to survive a 20 min thermal treatment and showed a similar behavior, i.e. an inactivation of about 6 log units in the first 2–4 min of treatment, followed by constant survivor counts (2–4 log CFU/ml). The pre-culture of staphylococci under stressing conditions (high NaCl concentration and low pH) increased the susceptibility to thermal treatment in three strains isolated from food matrices. The addition of carvacrol and citral during thermal treatment influenced the number of survived cells at the end of the treatment. This new insight in the thermal resistance of staphylococci needs to be better investigated, in order to study proper strategies to control their occurrence and behavior in real food systems. Highlights: Staphylococci are able to survive a thermal treatment at 80 °C for 20 min. Growth under stressing conditions (high NaCl concentration, low pH) decreases the thermal resistance of some strains. The addition of carvacrol and, to a lesser extent, citral during thermal treatment decreased the number of survivors.