title: Investigating the potential of Bacillus subtilis alpha-amylase as a pressure-temperature-time indicator for high hydrostatic pressure pasteurization processes.
abstract: The potential of Bacillus subtilis alpha-amylase (BSA) as a pressure-temperature-time indicator (pTTI) for high pressure pasteurization processing (400-600 MPa; T(i) 10-40 degrees C; 1-15 min) was investigated. A stepwise approach was followed for the development of an enzyme-based, extrinsic, isolated pTTI. First, based on literature data on the pressure stability, BSA was selected as a candidate indicator. Next to the accuracy and ease of the measurement of the indicator's response (residual activity) to the pressure treatment, the storage and handling stability of BSA at atmospheric pressure was verified. Second, the stability of BSA at a constant temperature (T) and time in function of pressure (p) was investigated. Solvent engineering was used to shift the inactivation window of BSA in the processing range of interest. Third, the enzyme (1 g/L BSA-MES 0.05 M pH 5.0) was kinetically calibrated under isobaric-isothermal conditions. Time dependent changes in activity could be modeled best by a first-order model. Except for low pressures and high temperatures, a synergistic effect between pressure and temperature could be observed. Based on the model selected to describe the combined p,T-dependency of the inactivation rate constant, an elliptically shaped isorate contour plot could be constructed, illustrating the processing range where BSA can be used to demonstrate temperature gradients. Fourth, the validity of the kinetic model was tested successfully under dynamic conditions similar to those used in food industry. Finally, the indicator was found suitable to demonstrate nonuniformity in two-sectional planes of a vertical, single vessel system.
authors: Laboratory of Food Technology, Leuven Food Science and Nutrition Research Centre (LFoRCe), Deptartment of Microbial and Molecular Systems (M2S), Katholieke Universiteit Leuven, B-3001 Heverlee, Belgium.
authors: Tara
authors: T
authors: Grauwet
authors: Iesel
authors: I
authors: Van der Plancken
authors: Liesbeth
authors: L
authors: Vervoort
authors: Marc E
authors: ME
authors: Hendrickx
authors: Ann
authors: A
authors: Van Loey
mesh_terms: D001412:Bacillus subtilis / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D004795:Enzyme Stability; D006874:Hydrostatic Pressure; D007700:Kinetics; D013242:Sterilization / Q000379:methods*; D013696:Temperature; D000516:alpha-Amylases / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D000516:alpha-Amylases