Effects of spray drying at different inlet air temperatures on antioxidative activity and some properties of homnil rice bran extract powder

Abstract

Background and Objective: Homnil rice bran (HRB) contains unstable bioactive compounds. Spray drying temperatures might affect on the antioxidative activity and other properties of HRB extract (HRBE) powder. Therefore, the objective of this work was to study the influence of spray drying at different inlet air temperatures on the antioxidant activity and some properties of HRBE powder. Materials and Methods: HRBE obtained from 2% citric acid extraction was added with 10DE maltodextrin and spray dried at various inlet air temperatures (100, 120 and 140°C). The effects of spray drying at different inlet air temperatures on their total phenolic content (TPC), total anthocyanin content (TAC) and DPPH scavenging activity (DPPH) were determined by spectrophotometric methods. The morphological properties were evaluated by scanning electron microscope. Results: The results showed that the TPC, TAC and DPPH scavenging activity of HRBE powder that was spray dried with 10 DE maltodextrin at 100°C were equivalent to 305.02 mg gallic acid (GAE)/100g, 215.12 mg cyanidin g per 100 g and 86.14%, respectively. These values were higher than those of the other inlet air temperatures (p≤0.05). The L*, a* and b* values were 28.23, 38.21 and 3.10. The range of water solubility index (WSI), water absorption index (WAI) and swelling capacity (SWC) of samples in this study was 50.21-59.25, 0.92-1.19 and 2.53-2.90%. The surface of the HRBE powder was smooth at 100°C and the sizes of the powder were in the range of 3-50 µm. The HRBE powder that spray drying with 10DE maltodextrin at the inlet air temperature of 100°C showed a low degradation of total anthocyanins and phenolics. The loss of total antioxidants and color difference were also at a low level. Conclusion: The HRBE powder could be prepared by spray drying with 10DE maltodextrin at the inlet air temperature of 100°C and it has a high potential to be used as bioactive food ingredients.