..Heating up to 37°C (98.6 F) causes loss of nearly 200 components, part of which are antibacterial
..Heating up to 40°C (104 F) destroys invertase, an important enzyme.
..Heating up to 50°C (122 F) for more than 48 hrs. turns the honey into caramel (the most valuable honey sugars become analogous to sugar).
..Heating honey higher than 140 degrees F for more than 2 hours will cause rapid degradation.
..Heating honey higher than 160 for any time period will cause rapid degradation and caramelization. Generally any larger temperature fluctuation (10°C is ideal for preservation of ripe honey) causes decay.
John Skinner, University of Tennessee