Waxy and high-amylose wheat starches and flours—characteristics, functionality and application

Starch is a predominant component of wheat grain. It plays an important role in appearance, structure and quality of food products. Starch consists of two kinds of glucose polymers (amylose and amylopectin) with the ratio of amylose/amylopectin ranging between 25–28 and 72–75%, respectively. The isoforms of granule-bound starch synthase (GBSS) are responsible for the biosynthesis of amylose fraction, whereas amylopectin synthesis is more complicated with concerted activities of the soluble starch synthase together with branching and de-branching enzymes. Recently, waxy (amylose-free) and high-amylose wheats produced through the development of new physicochemical and biological techniques provide the unique starch functional properties. The starches of these wheats have the specific structures and unique characteristics that are believed to enhance the quality of food products. In this review, we will focus on recent advances in the studies of the characteristics of waxy and high-amylose wheat flours and starches and their application for food processing. In addition, we also propose further research ideas for clearer understanding of their characteristics and for their effective utilization.