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Abstract
The kinetics of chlorophylls (a and b) degradation were studied in yerba maté leaves at different temperatures (50 to 808C) and water activities (0.1 to 0.8). Chlorophyll changes followed a first order-kinetic reaction in all cases. Rate constant values were fitted to different models to describe temperature and water activity dependence. When an Arrhenius model was used, the activation energy was found to be dependant on water activity for chlorophyll a (80.4–99.7 kJ/mol), while for chlorophyll b activation energy showed only a little variation (88.1–89.5 kJ/mol). Color parameter a* underwent a great decrease while parameters L* and b* had only a little variation.
ACKNOWLEDGMENT
The authors would like to thank Mr. Fernando Felicia for his help in color measurements.
Notes
19. IRAM 20503 (Instituto de Racionalización de Materiales). Yerba Mate: Determinación de la pérdida de Masa a 103 °C, 1995
