Soaking Induced Changes in Chemical Composition, Glycemic Index and Starch Characteristics of Basmati Rice

An attempt was made to determine the qualitative changes in basmati rice （Pusa Basmati 1121, PBl121） during soaking at 40 ℃ to 80 ℃. Soaking temperature had significant effect （a = 0.01） on chemical composition, glycemic index and starch characteristics of rice. Starch content, apparent amylose content, crude protein content and crude fat content in un-soaked rice were found to be 73.24%, 27.26%, 8.79% and 2.56%, respectively, but differences in these traits were observed after soaking. Amylose to amylopectin ratio （Am/Ap） decreased from 0.59 to 0.52 （soaked at 80 ℃）. Crude fibre and crude ash contents increased after soaking. The mineral composition （K, P, S, Ca, Mg, Mn, Fe, Cu and Zn） in soaked rice was found to be 16.46% higher than un-soaked rice at the same degree of polishing. Glycemic index of un-soaked rice was found to be 58.41, but decreased to 54.31 after soaking at 80 ℃. Pasting properties, scanning electron microscope images, and X-ray diffractograms suggested partial gelatinization of starch in the temperature range of 60 ℃ to 80 ℃. Based on qualitative changes in rice （apparent amylose content, Am/Ap ratio and crystallinity rate）, it was concluded that intermediate soakincl temperatures （60 ℃ to 70 ℃） would be useful for soaking of PB1121.

Variation in Gelatinization Characteristics of Storage Root Starch During Sweetpotato Growth and Development

The differential scanning calorimetry (DSC) and rapid visco-analyzer (RVA) were used to determine the starch gelatinizationcharacteristics during the growth of three sweetpotato cultivars. The results showed that the starch contents of threesweetpotato cultivars all decreased as growth progressed. Changes of the amylose contents differing in harvesting datesshould be discriminated according to the cultivars. At the early harvests amylose contents of Xushu18 and Zheda9201were relatively high, but those of Zhe3449 were low. As the growth duration of sweetpotatoes prolonged, the peaks ofDSC thermograms tended to occur at a low temperature and not to be so obstrusive with the increased width of the peak.Obvious decreases were observed, values of onset, peak and conclusion temperatures, as well as enthalpy of phasetransitions, as growth time lengthened. The peak viscosities, as determined through RVA, showed a rising tendency asgrowth progressed. In addition, statistical analysis revealed that there were correlations between the amylose content andgelatinization characteristics to some extent, which were affected by genotypes evidently.

Structural Characteristics of Semen coicis Resistant Starch and Its Effect on the Proliferation of Bifidobacterium bifidum

Semen coicis resistant starch is a type of starch which has undergone retrogradation. In this study,the structural characteristics of Semen coicis native starch,high-amylose maize starch,and heat-moisture treated Semen coicis resistant starch were investigated. The field emission scanning electron microscopy results indicated that compared to Semen coicis native starch and high-amylose maize starch,the surface of heat-moisture treated Semen coicis resistant starch was rough and full of irregular layered strips. The Fourier transform infrared spectroscopy measurements indicated the degree of ordered structure values of Semen coicis native starch,high-amylose maize starch,and heat-moisture treated Semen coicis resistant starch are 1.355,1.372,and 1.410,respectively,and the degree of double helix values is 1.931,1.942,and 2.027,respectively,indicating that the degree of ordered structure and double helix structure of heat-moisture treated Semen coicis resistant starch is both higher than those of Semen coicis native starch and high-amylose maize starch. ^（13） C nuclear magnetic resonance spectroscopy showed that Semen coicis native starch and high-amylose maize starch exhibited A-type crystal structures,while heat-moisture treated Semen coicis resistant starch displayed B-type crystal structures. The relative crystallinity of Semen coicis native starch,high-amylose maize starch,and heat-moisture treated Semen coicis resistant starch is 76.41,85.36,and 87.25,respectively,and the percentages of amorphous region are 5.78,4.72,and 4.39,respectively. Additionally,heat-moisture treated Semen coicis resistant starch could increase the proliferation of Bifidobacterium bifidum more than Semen coicis native starch or high-amylose maize starch. Bifidobacterium bifidum displayed a higher tolerance under simulated gastrointestinal tract conditions such as low p H,bile acid,pepsin,and trypsin in heat-moisture treated Semen coicis resistant starch medium than in Semen coicis native starch or high-amylose maize starch media.

The Source of Genes Related to Rice Grain Starch Synthesis Among Cultivated Varieties and Its Contribution to Quality

The property of starch in rice grain endosperm is a very important determinant for rice quality, and it is essential to understand the genetic effect of the genes related to starch synthesis in high-yielding rice varieties for rice quality improvement. The physicochemical properties （e.g., amylose content, gel consistency, and RVA profile） were assessed on 53 rice varieties, including certain typical indica/japonica landraces and certain high-yielding modern varieties. And molecular markers for Sbel, Sbe3 developed on the basis of sequence diversities between the rice subspecies indica and japonica, together with PCR-Acc I marker for Wx gene were used to investigate the genotypes of 53 rice cultivars. The result showed that the developed molecular markers for Wx, Sbel, Sbe3 could distinguish indica or japonica alleles at three loci. Among all the 53 rice cultivars, six genotypes were observed when Sbel, Sbe3, and Wx loci were considered together, while the genotypes of WxiSbelJSbe3i and WxiSbelJSbe3J were absent. In order to explore the genetic effects of the three genes, especially for starch branching enzyme genes, ANOVA and multiple comparison analysis were conducted. The results showed that rice cultivars with different genotypes exhibited different phenotypes, including amylose content, gel consistency and certain RVA characteristics, and the significant differences among the six genotypes were observed. It was concluded that these three genes had randomly recombined during the process of the rice variety development. And the genetic effects of indica and japonica alleles at three gene loci were different, of which, Wx gene plays a major role in determining the starch properties, followed by Sbel and Sbe3, and the genetic effects of Sbel and Sbe3 in different backgrounds （Wx~, WxJ） are different. The results have provided a clue for rice good quality variety development, and the molecular markers will benefit to the improvement in quality of rice.

Comparative Study on the Structural and Physicochemical Properties of Flour and Starch from Dioscorea opposita Thunb

The objective of this work was to investigate and compare the structural and physicochemical properties of Dioscorea opposita Thunb. flour（DF）, starch（DS） and purified starch（PDS）. DS and PDS showed higher total starch and amylose content as compared to DF. Starch granules of DF were oval shape with rough surface while DS and PDS were relatively smooth by SEM. According to XRD measurements, FT-IR spectroscopy and 13 C CP/MAS NMR spectroscopy, all samples displayed C-type crystalline pattern, and PDS displayed the highest relative crystallinity and short-range order structure. However, DF contained the greatest content of the amorphous-phase. DF displayed the absorption peaks at 1730 and 1560 cm^-1 related to the characteristic groups of lipid and protein using FT-IR spectroscopy. Furthermore, DF exhibited significantly higher pasting temperature while DS displayed the great peak and breakdown viscosity, as well as PDS had the highest setback and final viscosity, presumably due to the chemical composition and structural differences. DF exhibited the highest gelatinization temperature whereas PDS displayed the greatest gelatinization enthalpy. The pasting and gelatinization properties of flour and starch might be related to the relative crystallinity, short-range order structure or the interactions between starch and its associated compounds. The results allow the improvement in the manufacture of Dioscorea opposita Thunb. flour and starch with desirable pasting and gelatinization properties.