A new proposed sweet potato starch granule structure--pomegranate concept.

There are two competing concepts about organization of starch granule, fibrillar concept (or amylopectin clustering concept) and blocklet concept. A new micrograph of gelatinized sweet potato starch mixed with lactose might combine the two concepts and recover the mysterious structure of starch granule. Here we propose a possible granule structure of sweet potato starch by analyzing its gelatinization micrographs mixed with different carbohydrates. As the structure of pomegranate, out-layer of granule is equivalent to skin of pomegranate, blocklets are same to garnet of pomegranate, the amylopectin clusters with one reducing end at hilum, equivalent to primary body of pomegranate, constitute the basic structure of granule, in the special parts of the clusters, lots of blocklets form and increase, very like the born of garnet of pomegranate. At the same time double helix appears in blocklets, the arrangements of blocklets, same as garnet in pomegranate, form the semi-crystalline growth rings. The crystal type of starch is determined by arrangement of blocklet on it, hexagonal for A type, monoclinic for B type.