The effect of air flow in coffee roasting for antioxidant activity and total polyphenol content

- The effect of air flow, temperature and time in coffee roasting was modeled.
- Quadratic effect of air flow was observed for antioxidant activity in coffee roasting.
- Increase or decrease of air flow can deliver higher antioxidant activity of coffee.
- Antioxidant activity was a suitable parameter for nutritional quality of coffee beans.

The objective of this study was to investigate the effect of air flow in coffee roasting for antioxidant activity and phenolic compound content. Roasting was conducted in various combinations of temperature (180-200 °C), time (13-17 min) and volume flow rate (VFR; −0.271-0.271 L/s) using Box-Behnken design. The results of DPPH, ORAC and total polyphenol content (TPC) were fitted to the response surface methodology models (R2 = 0.9936-0.9869). Increasing temperature and time were negatively influenced for functional properties of roasted coffee with significances (P < 0.05). The quadratic effect of VFR was observed in DPPH and ORAC assays. Higher DPPH and ORAC values were shown in high or low VFR than the centre point of VFR at the same temperature or time. On the other hand, TPC was decreased from high to low VFR at the same temperature or time. The VFR was a significant parameter for antioxidant activity and TPC in coffee roasting. Manipulation of air flow by increasing or decreasing VFR can deliver higher antioxidants and phenolic compounds from the same amount of coffee beans to consumers.