Heat degradation kinetics of the chlorophyll from spinach and its correlation with the reflection spectra

Abstract

Chlorophyll, the pigment responsible for the green color specific to the spinach leaves, is sensitive to temperature, pH, activity of enzymes. The heat degradation kinetics of the chlorophyll a and chlorophyll b from the spinach leaves was studied at different temperatures (60, 70, 80 and 90°C) and different times (3, 9, 12, 15 min). The degradation of the chlorophyll a and chlorophyll b followed a first-order reaction, and the rate constant had values between 0.0199-0.0695 min-1 for chlorophyll a and 0042-0.011 min-1 for chlorophyll b respectively. The dependence between the chlorophyll degradation and temperature was modeled using the Arrhenius'a equation. The activation energy was by 44.316 Kjmol-1 for chlorophyll a and 35.384 Kjmol-1 for chlorophyll b respectively. Using the rapid, non-invasive measuring method of the reflection spectra in red band and in NIR region and the calculation of the index Clred edge, the chlorophyll quantity from spinach leaves was measured with a relative error ErCle between 1.27 and 8.65%.