;This is the first report on regulation of the isoamylase1 gene to modify the structure of amylopectin and properties of starch by using antisense technology in plants. The reduction of isoamylase1 protein by about 94% in rice endosperm changed amylopectin into a water-insoluble modified amylopectin and a water-soluble polyglucan (WSP). As compared with wild-type amylopectin, the modified amylopectin had more short chains with a degree of polymerization of 5-12, while their molecular sizes were similar. The WSP, which structurally resembled the phytoglycogen in isoamylase-deficient sugary-1 mutants, accounted for about 16% of the total a-polyglucans in antisense endosperm, and it was distributed throughout the whole endosperm unlike in sugary-1 mutant. The reduction of isoamylase activity markedly lowered the gelatinization temperature from 54 to 43°C and the viscosity, and modified X-ray diffraction pattern and the granule morphology of the starch. The activity of pullulanase, the other type of starch debranching enzyme, in the antisense endosperm was similar to that in wild-type, whereas it is deficient in sugary-1 mutants. These results indicate that the isoamylase1 is essential for amylopectin biosynthesis in rice endosperm, and that alteration of the isoamylase activity is an effective means to modify the physicochemical properties and granular structure of starch.

The objectives of this study were to characterize starches isolated from potato, canna, fern, and kudzu, grown in Hangzhou, China, for potential food and nonfood applications and to gain understandings of the structures and properties of tuber and root starches. Potato and canna starches with B-type X-ray patterns had larger proportions of amylopectin (AP) long branch chains (DP g37) than did fern (C-type) and kudzu (CA-type) starches. The analysis of Naegeli dextrins suggested that fern and kudzu starches had more branch points, R-(1,6)-D-glycosidic linkages, located within the double-helical crystalline lamella than did the B-type starches. Dispersed molecular densities of the C-and CA-type APs (11.6-13.5 g/mol/nm3) were significantly larger than those of the B-type APs (1.4-6.1 g/mol/nm3) in dilute solutions. The larger proportion of the long AP branch chains in the B-type starch granules resulted in greater gelatinization enthalpy changes (ΔH). Retrograded kudzu starch, which had the shortest average chain length (DP 25.1), melted at a lower temperature (37.9 °C) than the others. Higher peak viscosities (550-749 RVU at 8%, dsb) of potato starches were attributed to the greater concentrations of phosphate monoesters, longer branch chains, and larger granule sizes compared with other tuber and root starches. KeywordsCenter for Crops Utilization and Research, Amylose, amylopectin, molecular weight, dispersed molecular density, gelatinization, retrogradation, pasting The objectives of this study were to characterize starches isolated from potato, canna, fern, and kudzu, grown in Hangzhou, China, for potential food and nonfood applications and to gain understandings of the structures and properties of tuber and root starches. Potato and canna starches with B-type X-ray patterns had larger proportions of amylopectin (AP) long branch chains (DP g37) than did fern (C-type) and kudzu (C A -type) starches. The analysis of Naegeli dextrins suggested that fern and kudzu starches had more branch points, R-(1,6)-D-glycosidic linkages, located within the double-helical crystalline lamella than did the B-type starches. Dispersed molecular densities of the C-and C A -type APs (11.6-13.5 g/mol/nm 3 ) were significantly larger than those of the B-type APs (1.4-6.1 g/mol/nm 3 ) in dilute solutions. The larger proportion of the long AP branch chains in the B-type starch granules resulted in greater gelatinization enthalpy changes (∆H). Retrograded kudzu starch, which had the shortest average chain length (DP 25.1), melted at a lower temperature (37.9°C) than the others. Higher peak viscosities (550-749 RVU at 8%, dsb) of potato starches were attributed to the greater concentrations of phosphate monoesters, longer branch chains, and larger granule sizes compared with other tuber and root starches.

The intense and complex flavor characteristics of soy sauce makes it very difficult to obtain a comprehensive sensory profiling, and an effective descriptive analysis protocol for soy sauce products has not yet been established. The aims of this study were (1) to establish an objective, effective, and powerful descriptive analysis procedure that can be used to understand the sensory characteristics of soy sauce products and (2) to evaluate the sensory characteristics of 6 fermented type soy sauces with high market share in Korea. The test procedures, reference standards, and definitions for the descriptive terms of soy sauces were developed by 8 trained panelists. Panelists developed 11 aroma attributes, 10 flavor attributes, and 1 mouth feel attribute for evaluating the sensory characteristics of soy sauces. The data set were statistically analyzed by analysis of variance and principal component analysis. There were significant differences among the soy sauce samples in the intensity of all the sensory attributes. The 1st and 2nd principal component (PC) explained 53.6% and 23.5% of the total variation, respectively. The basic taste attributes and fermented/chemical attributes were the dominant attributes defining PC1 and PC2 axes, respectively.

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