Bacterial spore inactivation at 45–65 °C using high pressure processing: Study of Alicyclobacillus acidoterrestris in orange juice

High pressure processing (HPP) is a new non-thermal technology commercially used to pasteurize fruit juices and extend shelf-life, while preserving delicate aromas/flavours and bioactive constituents. Given the spoilage incidents and economic losses due to Alicyclobacillus acidoterrestris in the fruit juice industry, the use of high pressure (200 MPa – 600 MPa) in combination with mild temperature (45 °C–65 °C) for 1–15 min, to inactivate these spores in orange juice were investigated. As expected, the higher the temperature, pressure and time, the larger was the A. acidoterrestris inactivation. The survival curves were described by the first order Bigelow model. For 200 MPa, D45 °C = 43.9 min, D55 °C = 28.8 min, D65 °C = 5.0 min and z-value = 21.3 °C. At 600 MPa, D45 °C = 12.9 min, D55 °C = 7.0 min, D65 °C = 3.4 min and z-value = 34.4 °C. Spores were inactivated at 45 °C and 600 MPa, and at 65 °C only 200 MPa was needed to achieve reduction in spore numbers. Results demonstrated that HPP allowed A. acidoterrestris spore inactivation at lower temperatures (45–65 °C) than conventional thermal processing (85–95 °C) without pressure, yielding a fresher and higher quality preserved food.