and therefore the potential use, practical implications and quantification
of Stevia as an enzyme inhibitor is still a subject of research.
The kinetics of the enzyme inactivation process describes its
progress with time. The way in which inactivation progresses as a
function of time is expressed by the mathematical form of the kinetic
model. The rate of inactivation is reflected by the numerical
values of the kinetic parameter estimates. These parameters, along
with their recognised limitations, are used to analyse and report the
variation of a component as a function of process settings. Thus, the
estimation of an enzyme kinetic parameter in the presence of its
inhibitor represents a measure of the inhibition rate. If the reaction
inhibited is an oxidation, the inhibition rate could also be an index
of antioxidant activity. Traditionally linear models have been
applied to describe enzyme inactivation kinetics, but lately some
microbial inactivation kinetic models (Weibull distribution) have
been applied to describe enzyme inactivation kinetics (Elez-
Martínez, Aguilo-Aguayo, & Martín-Belloso, 2006; Sampedro &
Fan, 2014).
In this context, the objective of this work was not only to study
the capability of Stevia to inhibit PPO and POD from a mixture of
different fruits, orange, papaya and mango (rich in antioxidant
compounds, including phenolic compounds), at two different incubation
temperatures (10 and 37 C), but also to quantify the
antioxidant capacity of Stevia as a measure of PPO and POD percentage
of inhibition by the use of Weibull distribution function.