Characterizing the variability of enzymatic browning in fresh-cut apple slices

Abstract

Browning reaction variability in apple slices was characterized using a new procedure denominating the differential pixel method. Using this method, a kinetic rate and an empirical order of reaction were derived for each pixel in an image corresponding to a sliced apple surface undergoing browning; each pixel in the image can be seen as a small portion of the fruit. In the experiments, 40 samples of fresh-cut apple slice were put on a computer vision system and images recorded over time at a room temperature of 5 °C. Data was fitted to the Weibullian model kinetic. Results confirmed strong heterogeneity in the values of enzymatic browning kinetic rate on the apple surface; this variability was characterized as a normal logarithmical distribution, with a mean rate kinetic value of the −0.0117 ± 0.0036 units of L* decayed per minute. The empirical order of reaction was distributed on the surface following a normal statistical distribution with a mean equal to 0.451 ± 0.046. No statistical differences were established in the kinetic rate and in the empirical order when the differential pixel method was compared with the traditional method (where a mean of the L* intensity value was used).