Suitability of ccRSM as a tool to predict inactivation and its kinetics for Escherichia coli, Staphylococcus aureus and Pseudomonas fluorescens in homogenized milk treated by manothermosonication (MTS)

• Published in: Food control Vol. 39; pp. 41 - 48
• Main Authors: Cregenzán-Alberti, Oliver, Halpin, Rachel M., Whyte, Paul, Lyng, James, Noci, Francesco
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.05.2014; Elsevier
• Subjects: Biological and medical sciences; ccRSM; Escherichia coli; Food industries; Fundamental and applied biological sciences. Psychology; General aspects; Hygiene and safety; Milk; Pseudomonas fluorescens; Staphylococcus aureus; Ultrasound; Pseudomonas fluorescens; Ultrasound; ccRSM; Escherichia coli; Staphylococcus aureus; Milk; Pseudomonadales; Dairy product; Inactivation; Bacteria; Micrococcales; Pseudomonadaceae; Micrococcaceae; Kinetics; Enterobacteriaceae
• ISSN: 0956-7135; 1873-7129
• DOI: 10.1016/j.foodcont.2013.10.007

The application of ultrasound (US) technology (i.e. sonication) has been used as an alternative to thermal technologies to reduce the microbial population of foods and beverages. This approach can be used on its own or combined with pressure and temperature (i.e. manothermosonication (MTS)). Microbial inactivation kinetics by sonication remains unclear. In the present study, a central composite response surface model (ccRSM) was used in order to study the effects of temperature (20–52 °C), acoustic intensity (60–120 W/cm2) and treatment time (40–240 s) at a constant pressure (225 kPa) by MTS processing on microbial inactivation. Reductions of up to c. 1.6 log CFU/ml were achieved for Escherichia coli and Pseudomonas fluorescens. Lower inactivation values were reported for Staphylococcus aureus (1.05 log CFU/ml). These inactivation values were achieved using conditions of 36 °C, 90 W/cm2 and 240 s. Inactivation of E. coli by MTS (R2 = 0.90) was described by an exponential curve, whereas inactivation of S. aureus and P. fluorescens by MTS (R2 ≥ 0.73) were described by a linear trend. The coefficient of determination values were obtained following validation between the theoretical model and the experimental values. Statistical analysis showed that treatment time was the factor with greatest influence on microbial inactivation for all three microorganisms. The present study confirms the suitability of using ccRSM as a tool for investigating and predicting the inactivation of E. coli, S. aureus and P. fluorescens as a function of temperature, acoustic power and treatment time, and may also be useful for predicting inactivation of other microorganisms commonly found in raw milk. •Microbial inactivation kinetics due to ultrasound of three milk bacteria was assessed.•A maximum reduction of 1.6 log CFU/ml was achieved for Escherichia coli and Pseudomonas fluorescens.•Lower inactivation was observed for Staphylococcus aureus (1.05 log CFU/ml) following US treatment.•Inactivation of E. coli could be described by an exponential curve (R2 ≥ 0.90).•The inactivation of S. aureus and P. fluorescens followed a linear trend (R2 ≥ 0.73).