Abstract: Starch is used as an important ingredient or accessory material in the food industry and its molecular structure restricts the performance of starch-based products. It is generally accepted that starch is comprised mainly of highly branched amylopectin (AP) and predominantly linear amylose (AM). As the understanding of starch structure has been increasingly improved, the current widely accepted theories regarding amylose and amylopectin have become insufficient to solve many practical problems encountered in the study of starch function and structure. It has been demonstrated that there may be a third fraction defined as intermediate material (IM) intermediate between AP and AM in starch. IM is considered one of the major factors affecting starch properties, but its molecular structure is not clear yet, so that the structure and properties of starch is not fully understood. In this paper, we review the recent progress made in understanding the concept of IM as well as its separation, structure and properties, which will provide valuable information for studying the structure of starch and IM.

Key words: starch, amylose, amylopectin, intermediate material, molecular structure, functional properties