Chlorophyll was incorporated into chitosan films, forming intelligent systems able to detect variations in temperature. Chitosan is a biodegradable polymer that forms flexible, resistant films with an efficient oxygen barrier. Chlorophyll was added (0.25 g/100 g) into chitosan suspension (2.00 g/100 g) and intelligent films (FIQ) were cast. The effects of temperature (10 °C to 50 °C) and luminosity (0 to 1000 lx) on the films were studied using an experimental design with two variables, analyzing the color parameters L*, a*, b* and mechanical properties. The films were characterized according to their homogeneity, flexibility, color and handling. Chitosan suspensions containing chlorophyll were also applied as coating on the surface of pieces of card-paper, forming a card paper film system (S-FP). By visual inspection we observed the color of the S-FP changing irreversibly from green to yellow when the temperature was above 50 °C. Therefore, the S-FP system can potentially be used as a colorimetric indicator for the 50 °C to 70 °C range, being advantageous owing to the ease of fabrication, biodegradability, safe use for food and low cost.
Intelligent packaging; chitosan; chlorophyll; temperature indicator
