Water activity change at elevated temperatures and thermal resistance of Salmonella in all purpose wheat flour and peanut butter
Abstract Water activity (aw) is a major factor affecting pathogen heat resistance in low moisture foods. However, there is a lack of data for aw at elevated temperatures that occur during actual thermal processing conditions, and its influence on thermal tolerance of pathogens. The objective of this study was to gain an in depth understanding of the relationship between temperature induced changes in aw and thermal resistance of Salmonella in all purpose flour and peanut butter at elevated temperatures (80 oC) Equilibrium water sorption isotherms (water content vs. water activity) for all purpose wheat flour and peanut butter over the range of 20 to 80 degC were generated using a vapor sorption analyzer and a newly developed thermal cell. The thermal resistance (D80 values) of Salmonella in all purpose wheat flour and peanut butter with initial aw of 0.45 (measured at room temperature, 20 degC) was determined via isothermal treatment of small