Abstract: The influences of hot air drying, freeze drying and vacuum drying on the basic components, antioxidant properties and aromatic composition of whole flour from Pueraria lobata roots were studied. The results indicated that the contents of starch, protein, fat and other basic components in flours produced by different drying methods were significantly different (P < 0.05). The contents of total flavonoids and total phenolics in the flour prepared by freeze drying were 2.46 and 1.37 g/100 g, respectively, which were significantly higher than those obtained by the other drying methods (P < 0.05). The free radical scavenging activity, reducing power and metal ion chelating ability of the flour prepared by freeze drying were found to be the highest. On the other hand, the antioxidant capacity of hot air dried flour was the lowest. Analysis by solid-phase micro extraction (SPME) and gas chromatography-mass spectrometry (GC-MS) showed that a total of 43, 68, 66 and 64 volatile aromatic components were identified in fresh Pueraria lobata roots, and hot air dried, vacuum dried and freeze dried flours, respectively. This study found that vacuum drying and freeze drying provided better retention and even enhancement of the aroma components in fresh Pueraria lobata roots, while reducing some components contributing negatively to the flavor.

Key words: whole flour from Pueraria lobata roots, drying method, antioxidant properties, aromatic composition