Effects of inlet air temperature and spray rate of coating solution on quality attributes of turmeric extract coated rice using top-spray fluidized bed coating technique

Abstract

The addition of natural antioxidants onto white rice kernel can improve its functionality. Curcuminoids that present in turmeric rhizomes possess high antioxidant activity and heat stability. The objective of this study was to investigate the effects of inlet air temperatures and spray rates of turmeric extract solution on quality attributes of the turmeric extract coated rice (TCR) using the top-spray fluidized bed coating technique. The experimental results have shown that inlet air temperature and spray rate of coating solution strongly affected the final moisture content and percentage of fissured kernel of TCR. Almost all of TCR kernels in the bed cracked when their final moisture content was lower than 11.8% wet basis. However, the head coated rice yield of fissured TCR slightly decreased from that of white rice. The color of TCR was uniform over the entire surface. Texture of cooked TCR insignificantly changed from that of uncoated sample. Increasing spray rate provided higher both total phenolic content (TPC) and total antioxidant capacity (TAC) whilst increasing inlet temperature yielded lower TPC but it did not affect TAC. Retentions of TPC and TAC of TCR after cooking remained higher than 90%.