Tapioca starch (1%, w/w, db, distilled water) was heated by using a rapid visco analyzer (RVA) in four different programs, then the samples were settled and freeze dried, respectively. 
RVA
Morphological changes of blocklets during the gelatinization process of tapioca starch.After combined hydrolysis by α-amylase and β-amylase at room temperature, spherical blocklets in diameters of 27-60nm were observed on the surface of tapioca starch granules by scanning electron micrography (SEM).  The SEM images showed that the blocklets swelled at 52°C; the swollen blocklets deformed to olive shape, and linked by molecular chains, formed bead-like structure at 62°C; they started to merge at 72°C (pasting temperature); then the blocklets fused together and their shapes disappeared completely, and the gel network formed at 95°C. 
SEM