Comparison of Starch Physicochemical Properties of Waxy Rice Cultivars with Different Hardening Rates

Abstract

Cereal Chem. 94(4):699-704The objective of this study was to investigate the starch characteristics of a novel waxy rice cultivar Hitachimochi 36 (H36) with an extremely slow hardening rate of waxy rice cake and the relationships between starch physicochemical properties and texture of waxy rice cake. Starch isolated from H36 showed significantly higher digestibility than that from other waxy rice cultivars, and the starch digestibility highly correlated with the starch crystallinity. The compressive force of the starch gel prepared from H36 was significantly lower than that from other cultivars when stored at 5°C for five days, which reflected the differences in endothermic enthalpies corresponding to retrograded amylopectin. Various textural parameters of cooked waxy rice cake prepared from H36 were also remarkably different from those of cooked waxy rice cake prepared from other waxy rice cultivars. The cooked waxy rice cake prepared from H36 exhibited the lowest compressive force and breaking force by tensile and rupture tests, respectively. The analysis of amylopectin chain length distribution indicated that amylopectin of H36 contained higher proportions of the short chains. The difference in amylopectin chain length distribution and lower crystallinity of starch contributed to the unique textural properties of waxy rice cake prepared from H36. † Corresponding

Comparison of textural properties and structure of gels prepared from cooked rice grain under different conditions

“…This suggests that the presence of ELCs in rice samples may confuse the relationship between apparent amylose content and rice gel hardness. The positive relationship between the recrystallization of amylopectin and the stiffness of concentrated starch gels has been observed in previous studies (Bertoft et al, 2016;Keetles et al, 1996a;Sasaki, Kawamata, & Okamoto, 2017;Wang & Wang, 2002). This implies that chain length of amylose has an important role in gel formation.…”

“…The proportion of amylopectin with DP6-9 chains was reported to retard amylopectin retrogradation (Shi & Seib, 1992). The positive relationship between the recrystallization of amylopectin and the stiffness of concentrated starch gels has been observed in previous studies (Bertoft et al, 2016;Keetles et al, 1996a;Sasaki, Kawamata, & Okamoto, 2017;Wang & Wang, 2002). This suggests that the short amylopectin chains (DP6-12)…”

Influence of anionic, neutral, and cationic polysaccharides on the in vitro digestibility of raw and gelatinized potato starch

“…As previously mentioned, the enzymatic hydrolysis of starch granules is affected by amylose/amylopectin ratio and molecular structure. A higher proportion of short chains has been indicated to increase rapidly digestible starch and decrease slowly digestible starch with regard to the molecular structure of amylopectin, as the short chains (A chains) cannot form stable double helices and, thus, induce loss of rigidity of starch granules, increasing their susceptibility to enzyme attack . The result implies that the difference in amylopectin structure could influence the differences in starch digestibility between potato cultivars.…”

“…A higher proportion of short chains has been indicated to increase rapidly digestible starch and decrease slowly digestible starch with regard to the molecular structure of amylopectin, as the short chains (A chains) cannot form stable double helices and, thus, induce loss of rigidity of starch granules, increasing their susceptibility to enzyme attack. 8,9,30 The result implies that the difference in amylopectin structure could influence the differences in starch digestibility between potato cultivars. On the contrary, a higher phosphorus content in potato starch has been reported to increase the resistance to enzymatic hydrolysis because amylolytic enzyme action is prevented by the esterified phosphate groups attached to the glucosyl residues of amylopectin.…”

Changes in physicochemical properties of rice flour by fermentation with koji and its potential use in gluten‐free noodles

“…Koji fermentation of rice grains changes the structure of the rice starch granules by increasing the ratio of amylopectin short chains affecting the gel properties. Previous studies asserted that short amylopectin chains inhibit the recrystallization of amylopectin, resulting in reduced rigidity of the rice gel network (Bertoft et al., 2016; Sasaki et al., 2017). However, these studies used rice varieties with different amylopectin chain structures, and our results of chain structure alterations by fermentation treatment may not be comparable.…”