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Native and modified starches are important raw materials used in the industry. Gelatinization and rheological properties of starch are primary physicochemical properties to determine its applications. Starch gelatinization refers to a process that starch loses the native order and crystalline structure of the granules and becomes amorphous. Key rheological properties of starch include pasting property, viscosity of starch paste, and rheological features of starch gel. In this review, gelatinization and rheological properties of native starches from different botanical sources are compared and impacts of other ingredients, including sugars, salts, and lipids, on the properties are summarized. The review also covers current understandings of the gelatinization and rheological properties of modified starches with different structures. The information provided will be useful for the applications of starch in the industry as well as fundamental research in this field.

Objectives of this study were to understand the physicochemical properties of a novel resistant starch (RS) made by complexing high‐amylose maize starch VII (HA7) with palmitic acid (PA), and its effects on reducing postprandial plasma‐glucose and insulin responses. The HA7 starch was heat‐treated and debranched using isoamylase (ISO) to enhance the starch‐lipid complex formation. The RS content of the HA7 starch debranched with ISO and complexed with PA (HA7+ISO+PA) was 52.7% determined using AOAC Method 991.43 for dietary fiber, which was greater than that of the HA7 control (35.4%). The increase in the RS content of the HA7+ISO+PA sample was attributed to the formation of retrograded debranched‐starch and starch‐lipid complex. The postprandial plasma‐glucose and insulin responses of 20 male human‐subjects after ingesting bread made from 60% (dry basis) HA7+ISO+PA were reduced to 55 and 43%, respectively, when compared with those after ingesting control white bread (as 100%) containing the same amount of total carbohydrates. The results suggested that the HA7+ISO+PA can be used for the interventions of insulin resistance and metabolic syndrome, including diabetes and obesity.

Starch granule morphology differs markedly among plant species. However, the mechanisms controlling starch granule morphology have not been elucidated. Rice (Oryza sativa) endosperm produces characteristic compound-type granules containing dozens of polyhedral starch granules within an amyloplast. Some other cereal species produce simple-type granules, in which only one starch granule is present per amyloplast. A double mutant rice deficient in the starch synthase (SS) genes SSIIIa and SSIVb (ss3a ss4b) produced spherical starch granules, whereas the parental single mutants produced polyhedral starch granules similar to the wild type. The ss3a ss4b amyloplasts contained compound-type starch granules during early developmental stages, and spherical granules were separated from each other during subsequent amyloplast development and seed dehydration. Analysis of glucan chain length distribution identified overlapping roles for SSIIIa and SSIVb in amylopectin chain synthesis, with a degree of polymerization of 42 or greater. Confocal fluorescence microscopy and immunoelectron microscopy of wild-type developing rice seeds revealed that the majority of SSIVb was localized between starch granules. Therefore, we propose that SSIIIa and SSIVb have crucial roles in determining starch granule morphology and in maintaining the amyloplast envelope structure. We present a model of spherical starch granule production.

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