Interactions of exposure time and temperature on thermostability and protein content of excisedIllicium parviflorum roots

A model was developed to describe interactive effects of exposure time and treatment on thermostability of excisedIllicium parviflorum Michx. root cell membranes using electrolyte leakage (Lc) procedures. Roots were moved from 25°C to treatment temperatures between 35°C and 60°C for 30 to 300 min. A sigmoidal response described Lc increases with increasing temperature at selected time exposures and the lethal exposure time decreased exponentially as temperature increased. The lethal temperature (52.0±1.1°C) for a 15 min exposure using this technique was comparable to the critical temperature (52.2±1.2°C) when roots were exposed to gradually increasing temperatures (4°C per h). Total protein content of roots began to decrease as temperatures increased from 35 to 40°C and the temperature corresponding to 50% reduction in total proteins was 49.1±2.2°C.