Effects of drying temperature on the bioactive and technological properties of turmeric (Curcuma longa L.) flour

Abstract The objective of this study was to evaluate the influence of drying treatment on the characteristics physical, chemical, technological properties and bioactive of turmeric flour. The flour was obtained from the drying of rhizomes in a forced air circulation oven at temperatures of 45, 55, 65 and 75 °C. The analyzes performed were: pH, instrumental color, microstructure, granulometry, water and oil absorption indices, water solubility indices, and antioxidant activity. The characteristics of the flours significantly affected were moisture, protein, lipid and ash contents. The antioxidant capacity with the DPPH radical, for flour at the drying temperature of 45 °C, presented the highest value 36.55 Mmol Trolox g-1, and 7686.32 Mmol FeSO4 g-1 the FRAP radical at 65 °C.The phenolic content varied according to the solvent applied to obtain the extract, the mean values of total phenolic compounds for each temperature were: 0.419, 0.332, 0.316, 0.283 mg GAEa 100 g-1for temperatures 45, 55, 65 and 75°C respectively. Water solubility index (WSI) and oil absorption index ranged from 12.45 g g-1 to 11.78 g g-1 and from 2.54 g g-1 to 2.49 g g-1, respectively, for temperatures of 45 °C and 75 °C. The results of the present study indicated that temperature influences the physicochemical and technological properties of turmeric flour.