Optimization of cocoa roasting process using static tray and rotary drum to maximize phenolics content and antioxidant capacity by response surface method

In the cocoa industry, roasting is a key process for releasing the aroma and flavor precursors that will influence consumer acceptability. Roasting can be achieved via heat transfer through convection and/or conduction. It can affect the total phenolic content (TPC) and antioxidant capacity (AC) of the resulting cocoa nibs. This research aimed to optimize the parameters, such as temperature (100, 120, and 140 °C) and time (10, 20, and 30 min), in cocoa roasting using a static tray roaster (STR) and rotary drum roaster (RDR) to maximize the TPC and AC (ferric reducing antioxidant potential (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays) of nibs. Using response surface methodology, the optimal temperature and time were determined as 130 °C and 11 min for the STR (TPC = 63.72 ± 1.84 mg GAE/g; FRAP = 267.93 ± 5.30 μmol Eq. Trolox/g; DPPH = 418.91 ± 3.86 μmol Eq. Trolox/g) and 127 °C and 11 min for the RDR (TPC = 63.72 ± 1.84 mg GAE/g; FRAP = 267.93 ± 5.30 μmol Eq. Trolox/g; DPPH = 418.91 ± 3.86 μmol Eq. Trolox/g), respectively. Finally, no significant differences were observed between the roasting methods in terms of the TPC and AC (p < 0.05).