Evaluation of Changes in Alkyl Pyrazines, Color and Sensory Properties of Cocoa Powder under Different Roasting Conditions

Cocoa is an important product in the world and the raw material for the production of cocoa powder, which is widely used in the chocolate and food industries. Its value and quality are related to its unique and complex flavor combinations. The most important of these compounds are pyrazines, which are known to be the key components of the cocoa flavor. Since roasting is one of the most important steps in the process of producing cocoa powder, in the present study, the effect of roasting temperature (120, 130 and 140 °C) and time (20, 30 and 40 min) on flavor (alkyl pyrazines), color and sensory properties of cocoa powder were studied as the most important characteristics of cocoa quality and acceptability. Alkyl pyrazine compounds were analyzed by gas chromatography-mass spectrometry. The results showed that by changing the roasting temperature and time, the browning index (OD460/OD525) (P≤0.05) as well as the amount of alkyl pyrazines changed significantly (P≤0.01). Roasted cocoa powder at 140 °C for 40 min showed the highest browning index, tetra-methyl pyrazine to tri-methyl pyrazine (TMP/TrMP) ratio and sensory evaluation score compared to other samples.