Effects of Drying Methods on Properties of Yam Flours

The raw/cooked yam flours were prepared by vacuum drying,freeze vacuum drying and spray drying to study their rheological properties,gelatinization properties and digestion properties,and to explore the mechanism of properties change. The results showed that raw yam flour reflected a higher paste temperature,and the freeze-dried cooked yam flour had higher peak viscosity(3619.50 cP). The yam flours dried by different drying methods showed non-Newtonian fluid characteristics,and the viscoelasticity of frozen cooked yam flour was the highest. The raw yam flour showed a complete shape of starch granules,and the granule morphology of cooked yam flour varied greatly. The ripening treatment significantly reduced the contents of resistant starch in yam flour. The vacuum-dried cooked yam flour had the highest resistant starch content(56.11%). Among the three drying methods,freeze vacuum drying better retained the native physicochemical properties of yam flour.