Texture and Antioxidant Properties of Puffed Pounded-Unripe Rice Coated by Marigold Extract as Affected by Fluidized-Bed Coating Conditions

Abstract

We investigated the effects of fluidized-bed coating parameters on texture and antioxidant properties of puffed pounded-unripe rice (PPUR) coated by marigold extract with variations of inlet air temperature of 50, 60 and 70°C and coating solution feed rate of 5, 7.5 and 10 ml/min. The results showed that increasing inlet air temperature tended to reduce the hardness of coated PPUR, while the adverse effect was found with increasing feed rate. Both parameters did not significantly affect the crispiness. We also found that fluidizing air temperature and feed rate significantly affect total phenolic content (TPC), total flavonoid content (TFC) and their antioxidant activities. Higher feed rate slightly increased TPC and antioxidant activities as determined by DPPH and FRAP assays, but not for TFC. As mostly found in medicinal plants, all antioxidant properties decreased when temperature increased. Based on the amount of TPC and TFC and their antioxidant activities, we recommend low inlet air temperature and high feed rate to improve health benefits of puffed pounded-unripe rice as a breakfast cereal. However, agglomeration must be concerned when using high feed rate.