Two micro-mechanical techniques for studying the enzymatic maceration kinetics of apple parenchyma Original Research Article

The enzymatic texture loss during apple maceration was studied by two micro-mechanical techniques. The first technique consisted of a 5% strain compression cycles at a strain rate of 4.5 × 10−4 s−1. The second technique consisted on micro-puncture of the apple parenchyma with a small needle. The first technique led to the peripheral tissues degradation modelling with a first order kinetic reaction or a more pertinent Weibull function. The second technique evidenced that the jagged part of the load vs penetration curve corresponded to an interaction between the needle tip and the turgescent apple texture and the fractal dimension of this jagged part was chosen as the texture parameter. Modelling the enzyme diffusion phenomenon with the second Fick’s law and taking into account the model previously established on peripheral tissues allowed the estimation of an equivalent enzyme diffusivity through the apple parenchyma varying between 3.5 × 10−11 and 5.5 × 10−11 m2 s−1.