Yams.

This chapter discusses the extraction of starch from different yam (Dioscorea) species. The physiochemical (biochemical property, amylose and amylopectin content), structural (granular morphology, X-ray diffraction pattern, starch crystallinity, and amylose and amylopectin structure), functional (swelling pattern, solubility, viscosity, rheological properties and retrogradation) and thermal properties of yam starches and their digestibility are described.

Other starches.

This chapter discusses the extraction, physiochemical (chemical composition, amylose and amylopectin content), structural (granular morphology, X-ray diffraction pattern, starch crystallinity, and amylose and amylopectin structure), functional (swelling pattern, solubility, viscosity, rheological properties and retrogradation) and thermal properties, and digestibility of starches from minor tuber crops (e.g., arrowroot, Curcuma spp., Canna edulis [C. indica], Chinese water chestnut [Eleocharis dulcis], chayote [Sechium edule], Pachyrhizus ahipa, Oxalis tuberosa, Arracacia xanthorrhiza, Lilium spp.).

Aroids.

This book chapter outlines the extraction and purification, physiochemical composition (i.e. biochemical content, amylose and amylopectin content), structural properties (i.e. granular morphology, XRD and starch crystallinity, amylose and amylopectin structure), functional properties (i.e. swelling and solubility, viscosity, rheological properties, retrogradation), thermal properties (i.e. DSC, digestibility) of aroids.

Intra-Sample Heterogeneity of Potato Starch Reveals Fluctuation of Starch-Binding Proteins According to Granule Morphology

Starch granule morphology is highly variable depending on the botanical origin. Moreover, all investigated plant species display intra-tissular variability of granule size. In potato tubers, the size distribution of starch granules follows a unimodal pattern with diameters ranging from 5 to 100 µm. Several evidences indicate that granule morphology in plants is related to the complex starch metabolic pathway. However, the intra-sample variability of starch-binding metabolic proteins remains unknown. Here, we report on the molecular characterization of size-fractionated potato starch granules with average diameters of 14.2 ± 3.7 µm, 24.5 ± 6.5 µm, 47.7 ± 12.8 µm, and 61.8 ± 17.4 µm. In addition to changes in the phosphate contents as well as small differences in the amylopectin structure, we found that the starch-binding protein stoichiometry varies significantly according to granule size. Label-free quantitative proteomics of each granule fraction revealed that individual proteins can be grouped according to four distinct abundance patterns. This study corroborates that the starch proteome may influence starch granule growth and architecture and opens up new perspectives in understanding the dynamics of starch biosynthesis.

Seed Plumpness of Rice with Inhibition Expression of Starch Branching Enzymes and Starch Properties, Grain Position on Panicle

Cereal crops with inhibition expression of starch branching enzyme (SBE) contain highly resistant starch in the endosperm, and have potential health benefits for human. However, seed plumpness is significantly different, with different inhibition effects of SBE expression, resulting in differently shrunken seeds. In this study, a transgenic resistant starch rice line, which has highly resistant starch and is developed through inhibition expression of SBEs, had non-, slightly, and moderately shrunken seeds with plumpness from high to low. The differently shrunken seeds had significantly different seed weight and starch content. Different morphological starch granules were detected in the endosperm and had similar spatial distribution pattern among the non-, slightly, and moderately shrunken seeds. Starches from differently shrunken seeds had similar amylose content and amylopectin structure. The protein amount of amylose/amylopectin synthesis key enzymes in endosperm was no different between differently shrunken seeds. The primary branch of the panicle had a higher percentage of non-shrunken seeds than did the secondary branch at the same part of the panicle. From the upper part to the base of the panicle, non-shrunken seeds gradually decreased but slightly and moderately shrunken seeds gradually increased. The above results indicated that the differently shrunken seeds in transgenic rice line had the same SBE dosage, and the starch morphology and structure had no relationship with seed plumpness. The grain position on the panicle influenced seed plumpness, but had no effect on starch properties.

Understanding Starch Structure: Recent Progress

Starch is a major food supply for humanity. It is produced in seeds, rhizomes, roots and tubers in the form of semi-crystalline granules with unique properties for each plant. Though the size and morphology of the granules is specific for each plant species, their internal structures have remarkably similar architecture, consisting of growth rings, blocklets, and crystalline and amorphous lamellae. The basic components of starch granules are two polyglucans, namely amylose and amylopectin. The molecular structure of amylose is comparatively simple as it consists of glucose residues connected through α-(1,4)-linkages to long chains with a few α-(1,6)-branches. Amylopectin, which is the major component, has the same basic structure, but it has considerably shorter chains and a lot of α-(1,6)-branches. This results in a very complex, three-dimensional structure, the nature of which remains uncertain. Several models of the amylopectin structure have been suggested through the years, and in this review two models are described, namely the “cluster model” and the “building block backbone model”. The structure of the starch granules is discussed in light of both models.