Abstract:The effects of three processing technics (boiling, baking and freeze drying) on the basic components, antioxidant properties and aromatic composition of green bean powder were investigated. The results showed that the contents of starch, protein, flavonoids and polyphenols in flours pepared by different processing technologies were significantly different (p<0.05). The contents of total flavonoids and polyphenols in the green bean flour prepared by freeze drying were 0.40 g/g and 0.96 mg/g, respectively, and that in the green bean flour prepared by boiling method were 0.30 g/g and 0.71 mg/g, respectively. Compared to the baking technology, the free radical scavenging activity and reducing power of the flour prepared by boiling or freeze drying were found to be the highest. The antioxidant power of the powder obtained by baking green beans was the lowest. Analysis by solid-phase micro extraction (SPME) and gas chromatography-mass spectrometry (GC-MS) showed that a total of 17, 20, 41 and 21 volatile compounds were identified in fresh green beans, boiling, baking and freeze drying flours, respectively. Comprehensive analysis showed that the freeze driying and boiling green bean powder had higher antioxidant capacity. These above technologies could better preserve the nutritional value of green beans, and could better retain and increase the aroma of green beans. Due to a lot of energy consumption of freeze drying, boiling technology and then by hot air was selected.
