Glycemic index (GI) is commonly used to classify food carbohydrates according to acute blood glucose responses (Jenkins et al 1981), and to control the diets for diabetics and other patients with metabolic disorders (Food and Agriculture Organization 1998). Low-GI diets have been reported to effectively control the blood glucose level (Wolever 2004), improve lipid profiles, and reduce risk of cardiovascular disease (Brand Miller 1994, 2002; Morris and Zemel 1999; Roberts 2000; Lang 2004). These diets are favorable for dietary management of metabolic disorders because nutrient receptors in the gastrointestinal tract are stimulated for a longer period of time, resulting in prolonged satiety (Brand Miller 2002; Wolever and Mchling 2002). Rice is one of the major cereal crops consumed as a staple food in the world. Cooked rice is rapidly digested and absorbed, and thus the GI of cooked rice is known to be relatively high among various starchy foods. However, its glycemic response may vary in a wide range according to cultivar (Panlasigui et al 1991; Brand Miller et al 1992), cooking procedures (Brand Miller et al 1992; Foster-Powell and Brand Miller 1995), matrix structure (Jarvi et al 1995), and amylose-amylopectin ratio (Behall et al 1989; Panlasigui et al 1991; Frei et al 2003). Jenkins et al (1984) reported glycemic indices (GI) of cooked and brown rices to be 96 and 83, respectively. Brand Miller et al (1992) claimed that most rice cultivars, including white, brown, and parboiled rices, should be classified as high GI foods, whereas high-amylose rice was a potential low-GI food. Frei et al (2003) also reported that the GI of cooked rices from six different indigenous cultivars ranged from 68 to 109. The digestion of a carbohydrate changes with the presence of other food components (Bjorck 1996; Hoover and Zhou 2003). Various additives have been tested to improve the textural and sensory properties of cooked rice. Addition of surfactants (0.5% based on rice wt) decreased the roughness, hardness, stickiness, and moistness of the cooked nonwaxy and waxy rices (Kim et al 1997a). The hardess of a cooked normal rice was significantly decreased by adding cellulose (0.2% based on rice wt) (Kim and Ahn 1996). The rice cooked with sucrose fatty acid ester (0.25 or 0.5% based on rice wt) and isomaltooligosaccharide (0.5 or 1.0% based on rice wt) also resulted in decreased hardness (Kim et al 1997b). However, no study has been reported on their effects on the digestive behavior of cooked rice. Hydrocolloids are widely used as food additives to improve the stability and texture of host foods (Hoefler 2004), and they may also retard the retrogradation of many cereal products such as bread (Guarda et al 2004), rice cakes (Song and Park 2003), and tortillas (Friend et al 1993). Most hydrocolloids are readily soluble in water but rarely digested in human upper intestines (Edwards and Parrett 1996; Hoefler 2004), thus providing the same physiological effects as dietary fibers. In the present study, various hydrocolloids were added while rice was cooked, and their effects on the digestion and texture of the cooked rice were investigated. The glycemic response (GI value) based on the in vitro starch digestion profile was also determined.