Effect of hot-air drying temperature on the polyphenol content and the sensory properties of cocoa beans

Several studies have been reported on the potential health benefits of cocoa polyphenols. However, heat treatment on cocoa beans during drying has an inhibitory effect on the retention of its polyphenols. The polyphenol degradation mechanism due to heating is scarcely reported in literatures for cocoa beans. This paper aims to provide substantial evidence to prove that temperature and heating time has a negative effect on cocoa polyphenols. The study measured total polyphenols content of cocoa beans dried at 60°C, 70°C and 80°C respectively, at relative humidity (RH) level of 50% for heating time ranging from 0 to 40 h. Results showed that the total polyphenols content was found to be a maximum at 70°C drying temperature and reduced as the heating time for drying increased. This experiment confirmed the thermal degradation of polyphenols due to high temperature and exposure time with little effect from enzymatic activity especially at very low moisture content level. Sensory evaluation showed that astringency taste was rated higher for sample dried at 70°C.