Coupling of Water Activity and Colour Development of Roast Duck Skin under Forced Convection Drying

Roasting meat involves simultaneous heat and mass transfer, colour and flavour development and the formation of hazardous chemicals. The objectives of this study were to evaluate the effects of temperature and time on colour, 3,4-benzo(a)pyrene (BaP) and heterocyclic aromatic amines (HCAs) in roast duck skin during forced hot-air drying at less than 130 °C. The results showed that surface and internal temperatures of duck carcasses increased with drying time, rising to 111.9 and 83.7 °C, respectively. The curves of water activity (aw) and red index (a*) intersected at 50 min because of the decrease in aw and the increase in a* on the skin with drying time. The drastic decline in aw promoted colour development on the duck surface. BaP and carcinogenic HCAs were not detected in hot-air drying ducks, convincing us that the mild cooking method under forced hot-air drying could effectively reduce or eliminate the risk of certain human cancers.