1. IntroductionStarch is a major co

1. Introduction
Starch is a major constituent of rice and an important structural
constituent in many rice products (Sasaki et al., 2009). Rice starch
is not as widely used as starches derived from other sources due to
the high value of milled rice as food. The small size of rice starch
granules and the wide range of amylose content of rice varieties
provide opportunities for the development of a rice starch market
(Zhong et al., 2009). Rice starch is used as an additive in various
foods, industrial products, desserts, bakery products and as a fat
mimetic in foods such as ice cream, yoghurt and salad dressings
(Puchongkavarin, Varavinit, & Bergthaller, 2005).
Rice starch is composed of amylose and amylopectin. The ratio
of amylose to amylopectin and the branching properties of the
amylopectin molecules of a rice starch can affect the physical, textural and pasting properties of rice during the cooking of rice and
rice starch (Champagne, 1996).
The starch, in its native form, has limited use in the industry.
Physical and chemical modifications are commonly used to produce starches with special properties. Although chemically modified starches are available for industrial purposes, most
industries (especially the food and pharmaceutical industries) prefer starches that have not been chemically altered. Therefore, physically modified starch, by use of moisture, heat, shear, or radiation
has gained a wider acceptance, because there is no waste of
chemical reagents in the modified starch (Adebowale, Afolabi, &
Olu-Owolabi, 2005). Hydrothermal treatments (heat-moisture
treatment, HMT; and annealing, ANN) are physical modifications
that change the physicochemical properties of starch, without
destroying its granule structure. Both annealing and heat-moisture
treatments are related processes in which the starch to moisture
ratio, the temperature and heating time are critical parameters
that need to be controlled (Chung, Liu, & Hoover, 2009). The differences between these two treatments are the amount of water and
temperature used. Annealing occurs under a large excess of water
(50–60%) and occurs at relatively low temperatures (below the
gelatinisation temperature), whilst the HMT is carried out under
restricted moisture content (10–30%) and higher temperatures
(90–120C) (Maache-Rezzoug, Zarguili, Loisel, Queveau, & Buléon,
2008).
Regardless of origin of the starch, heat-moisture treatment promotes the increase of the gelatinisation transition temperatures,
the widening of the gelatinisation temperature range, a decrease
in the granular swelling and amylose leaching and an increase in
thermal stability. However, depending on the botanical origin
and treatment conditions, changes to the X-ray pattern, the formation of amylose–lipid complexes, the disruption of crystallinity, an
increase or decrease in enzyme susceptibility has been shown to
occur with HMT (Chung, Hoover, & Liu, 2009).
Different food products make different demands on the starches
to use in their formulations, depending on the desired properties of