Amylopectin is one of the major determinants of rice (Oryza sativa L.) grain quality, and a large difference in amylopectin is found between two subspecies: japonica and indica. However, the relationship among rice grain quality, indica/japonica genetic background, and amylopectin has not been clearly established. In this study, a series of backcross inbred lines derived from the cross between ...

It is known that crystalline amylopectin of starch plays a role of resistant starch. Although crystalline amylopectin of starchy food melts almost completely during its heat-processing, the melting may be prevented by a pre-dehydration treatment, because melting temperature of the crystalline amylopectin increases with a decrease in the water content of starch. In order to some insight into the...

During cotton leaf development, starch accumulation was characterized by an initial rise to a maximum at the second to the fourth leaf from the apex. Then, starch content progressively decreased with leaf age. Starch accumulation was inversely related to the ratio of amylopectin to amylose. Differences between leaves in this ratio resulted from variations in both amylose and amylopectin levels....

This work compared the molecular structures and physicochemical properties of starches obtained from chalky and translucent kernels of six rice cultivars. Starch samples were prepared according to a modified alkali steeping method. Crystallinity, pasting characteristics, and thermal properties were studied by X-ray diffraction, rapid viscosity analysis, and differential scanning calorimetry, re...

Blended cornstarch–xanthan gum systems were optimized for thickening of cocoa syrups. For this purpose the sensory (whole and partial), textural (force of penetration, adhesiveness and stringiness) and rheological properties (flow curves as well as viscosity/time and viscosity/temperature relationships) of cocoa syrups were studied. Flow curves were described by rheological model of Casson, whi...

Plastidial disproportionating enzyme1 (DPE1), an α-1,4-d-glucanotransferase, has been thought to be involved in storage starch synthesis in cereal crops. However, the precise function of DPE1 remains to be established. We present here the functional identification of DPE1 in storage starch synthesis in rice (Oryza sativa) by endosperm-specific gene overexpression and suppression. DPE1 overexpre...

Rice (Oryza sativa) allelic sugary1 (sug1) mutants defective in isoamylase 1 (ISA1) accumulate varying levels of starch and phytoglycogen in their endosperm, and the activity of a pullulanase-type of a debranching enzyme (PUL) was found to correlate closely with the severity of the sug1 phenotype. Thus, three PUL-deficient mutants were generated to investigate the function of PUL in starch bios...

Polysaccharide phosphorylase isolated from Idaho potatoes was the subject of a steady state kinetic study. The initial velocity of the reaction between a-D-glucopyranose l-phosphate (glucose-l-P) and amylopectin, in the absence of orthophosphate, was determined as a function of substrate concentration. A similar study was carried out for the reverse reaction. The result is characteristic of a s...

Amylose and amylopectin in corn and potato starches were fractionated by centrifugation at 124,000g for 3-72 h at 40 degrees C in a gradient media, Nycodenz, based on their sedimentation rate differences. The fractions were collected from a centrifuge tube, and then analyzed by the phenol-sulfuric acid method and iodine-binding test. Amylopectin, a large and highly branched starch molecule, mig...

The molecular structural parameters of six normal rice starches with different amylose contents were investigated through their iodine absorption spectra and gel permeation chromatography of fully branched and debranched starches. The thermal and digestion properties of starches were also determined and their relationships with molecular structural parameters were analyzed. Results showed that ...