Resumo

High hydrostatic pressure (HHP) has been a relatively new and attractive technology used to produce high quality and microbiological safe food products. This technology has been widely studied as an alternative to thermal processing and studies indicate that this process can inactivate microorganisms without altering the products’ organoleptic and nutritional qualities. Bacillus coagulans is a heat resistant bacterium of significant concern to the acid food industry. It is responsible for causing “flat sour” spoilage of canned foods and its spores are able to germinate and grow at pH values as low as 4. Thermal inactivation of B. coagulans spores in food products has been studied extensively but the effect of HHP on inactivation kinetic of B. coagulans spores is poorly characterized. The combined effect of HHP and moderate temperature (MT) has been effectively applied to inactivate microorganism spores while still minimizing the undesirable effects of heat on food quality. Accordingly, the aim of the present study was evaluate the combined effect of HHP and MT on the inactivation kinetic of B. coagulans spores in tomato pulp at 4 °Brix. Pressures from 300 to 600 MPa and temperatures of 50 and 60 °C were studied for up to 39 minutes. Inactivation kinetic parameters were obtained through the application of a primary Biphasic model. A pressure of 300 MPa and temperature of 50 °C resulted in a 2.0 log reduction after 15 min of holding. Using the same pressure, but increasing the temperature to 60 °C, a slightly greater log reduction was obtained (2.4). In contrast, a pressure of 600 MPa at 50 °C caused a 3.1 log reduction of B. coagulans spores, whereas increasing the temperature to 60 °C, resulted in an increase in the log reduction to 5.7. The HHP treatments at 60 °C showed a remarkable difference in the inactivation kinetics after 15 min of holding when the process changed from 300 to 600 MPa, showing a strong pressure dependence in the inactivation of B. coagulans spores in tomato pulp. These findings illustrate the improved efficiency of HHP with the application of moderate temperatures on the inactivation kinetic of B. coagulans spores, and how variations in pressure and temperature impact the effectiveness of the process. Results shown in this study may help in the design of processes for food preservation based on HHP technology.