Modeling the inactivation kinetics of fruit bromelain in pineapple during high-pressure and thermal treatments

The stability of fruit bromelain (FBM) in pineapple pulp was studied within a high-pressure domain of 0.1-600 MPa/30-70 degrees C/1 s-30 min. The pulse effect was quantified as a function of pressure, temperature, pressure build-up and decompression times. A maximum of 60% reduction in FBM activity was obtained after a single pulse of 600 MPa/70 degrees C. Upon applying nth order model, the obtained reaction order (n) for thermal (0.1 MPa/30-70 degrees C) and high-pressure (100-600 MPa/30-70 degrees C) inactivation was 1.1 and 1.2, respectively. The inactivation rate constant (k) ranged from 1.2 to 45.0 x 10(-3) Un - 1 min(-1). The activation energy was nonlinearly dependent on pressure (P); whereas, the activation volume was linearly related to temperature (T). The nonlinear dependence of k on P and T was modeled by an empirical equation. The D-values obtained from the empirical model appeared to be more realistic than those from the log-linear kinetics. Industrial relevance: Pineapple fruit bromelain (FBM) has numerous health benefits and therapeutic effects. It is a protease enzyme that helps in digestion. Processing of pineapple pulp needs attention towards retaining the maximum FBM activity in it. A detailed kinetic study of FBM within a broad range of pressure-temperature time domain will help in designing a high-pressure process for the pineapple pulp with respect to its bromelain stability. (C) 2016 Elsevier Ltd. All rights reserved.