Specific heat determination of plant barrier lipophilic components: biological implications.

The specific heat of isolated plant cuticles and their corresponding cuticular waxes have been measured for the physiological temperature in the range of 273-318 K at regular intervals. C(p) values ranged from 1.5 up to 4 J K(-1) g(-1) indicating a high cohesion, at the molecular level, of the molecular lipophilic components that constitute the plant cuticle. Second order phase transitions around 293 K, assigned to the cuticular matrix mainly constituted of the biopolyester cutin, have been detected and measured. Ecophysiological and physical implications of these thermodynamic data are discussed.