Impact of Refractance Window drying method on physical properties and phenolic antioxidants of tomato powder in comparison with other methods

Abstract

Abstract In this study, the quality properties of tomato powder prepared using the Refractance Window (RW) drying method was compared with microwave, hot air and sun drying methods. The bulk density, water solubility, vitamin C, total polyphenol compounds, optical density and color index of tomato powders were determined. The results of statistical analysis showed that the vitamin C content, phenolic compounds and solubility of samples dried by microwave and RW methods were significantly higher than the other methods (p<0.05). The lowest and the highest bulk density belonged to the powders prepared by microwave and RW respectively. In samples dried by RW method, L*, b* and a* index and color score was higher and the optical density was lower than other samples. The samples dried in microwave had the lowest L* value and highest optical density value, while the b* and a* index in these sample have been higher than the samples dried by sun and hot air drying methods. Also the lowest and the highest Hue and Chroma value were found in samples dried in hot air and RW respectively, while a*/b* ratio was reversed. But the highest and the lowest the total color (ΔE) value was in the samples dried in sun and RW method respectively. All in all, it can be concluded that the Refractance Window method can be used as a suitable alternative to hot air and microwave drying methods, without undesired effects on quality properties of tomato powders.