【Reading】あみろぺくちん

【English Name】Amylopectin

Amylopectin is a type of macromolecule that forms starch. Many α-glucose units are linked, taking a highly branched, net-like structure with α1-4 glycosidic bonds as the main chain and α1-6 glycosidic bond side chains extending here and there. Between adjacent branch points, roughly 20 glucose residues are said to line up.

What is important in relation to sushi is the starch composition of rice. The proportion of amylopectin in the starch of non-glutinous rice (uruchi-mai) reaches about 80%, and the starch of glutinous rice (mochi-gome) is almost entirely amylopectin. Because viscosity increases as the proportion of amylopectin rises, it is also deeply related to the texture and stickiness of the non-glutinous rice used for sushi.

Unlike amylose, amylopectin has low solubility in hot water. In the iodine-starch reaction it exhibits a red-purple color, clearly distinguished from the blue-purple shown by amylose. Its molecular weight is in the range of roughly 15 million to 40 million, a scale greatly exceeding that of amylose.

Because the cooked finish of sushi rice and the balance of grain definition and stickiness when made into vinegared rice are determined by the ratio of amylopectin and amylose contained in the rice, it can be called indispensable knowledge for understanding the quality of shari.