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Gelatinization Temperature (gelatinization + temperature)

Distribution by Scientific Domains

Chemistry	57%
Life Sciences	42%

Selected Abstracts

Gelatinization temperature of rice explained by polymorphisms in starch synthase

PLANT BIOTECHNOLOGY JOURNAL, Issue 1 2006
Daniel L. E. Waters
Summary The cooking quality of rice is associated with the starch gelatinization temperature (GT). Rice genotypes with low GT have probably been selected for their cooking quality by humans during domestication. We now report polymorphisms in starch synthase IIa (SSIIa) that explain the variation in rice starch GT. Sequence analysis of the eight exons of SSIIa identified significant polymorphism in only exon 8. These single nucleotide polymorphisms (SNPs) were determined in 70 diverse genotypes of rice. Two SNPs could classify all 70 genotypes into either high GT or low GT types which differed in GT by 8 °C. ,A' rather than ,G' at base 2412 determined whether a methionine or valine was present at the corresponding amino acid residue in SSIIa, whilst two adjacent SNPs at bases 2543 and 2544 coded for either leucine (GC) or phenylalanine (TT). Rice varieties with high GT starch had a combination of valine and leucine at these residues. In contrast, rice varieties with low GT starch had a combination of either methionine and leucine or valine and phenylalanine at these same residues. At least two distinct polymorphisms have apparently been selected for their desirable cooking qualities in the domestication of rice. [source]

Investigation of the gelatinization and extrusion processes of corn starch

ADVANCES IN POLYMER TECHNOLOGY, Issue 1 2002
Roberta C. R. Souza
Abstract The gelatinization and extrusion processes of corn starch were studied. Differential scanning calorimetry was used to determine the gelatinization temperature as a function of the water content. Plasticized corn starch was processed in single- and twin-screw extruders to produce thermoplastic materials. The mechanical properties of the films obtained in the twin-screw extruder with the addition of different quantities of water were evaluated. Dynamic mechanical analysis applied to thermoplastic starch samples obtained with 33% (w/w) total plasticizers showed two transitions, attributed to the presence of two phases in the starch,glycerol,water system. © 2002 John Wiley & Sons, Inc. Adv Polym Techn 21: 17,24, 2002; DOI 10.1002/adv.10007 [source]

STUDY OF SAGO STARCH (METROXYLON SAGU) GELATINIZATION BY DIFFERENTIAL SCANNING CALORIMETRY

JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2 2001
YAAKOB B. CHE MAN
Differential scanning calorimetry (DSC), at various heating rates (1,30C/min) and water:starch ratios (0.1:1,4:1), was used to study gelatinization phenomena of sago starch. The results showed that the gelatinization temperature and enthalpy (, H) of starches in excess water were 60,77C and 15.5,15.8 J/g, respectively. , H of gelatinization remained substantially the same at excess water contents, but decreased significantly beyond a water:starch ratio of 1.3:1. A single endothermic transition (G) that transformed into a double endotherm (G and M1) and only M1 occurred, respectively, at excess, intermediate and limited water contents. At 50% water content, evidence of the M1 endotherm was observed, and 85C represented the effective conclusion temperature (Tm) at the end of melting for sago starch. The experimental data were treated thermody-namically by applying an equation describing phase transitions of semi-crystalline polymers. The calculated value for the melting point of the undiluted polymer (Tm) was 432 K (R2= 0.96). [source]

Rheological Characteristics and Morphology of Dialdehyde Starch/Meat Composites during Heating

JOURNAL OF FOOD SCIENCE, Issue 2 2009
P.Y. Chiang
ABSTRACT:, Dialdehyde starch (DAS) was added to pork ham batter. The effects of DAS on the meat protein gel during heating were investigated using thermal and rheological analyses. In this study, the degree of DAS oxidation was controlled by the reaction time. The DSC thermogram showed that increasing the degree of oxidation resulted in DAS having a higher gelatinization temperature and lower heat absorption. In dialdehyde starch/meat (DAS/M) composites, meat protein reduced the availability of water to starch and raised the gelatinization temperature and heat absorbed by the composites. The G,max of the composites was greater than the linear combination of their components. The rheological properties of DAS were a major factor affecting the properties of its composites. Scanning electron microscopy and light microscopy with the aid of histologic technique revealed the network and distribution of DAS and DAS/M composites. The protein matrix formed the backbone of the network and gelatinized starch was trapped in the protein structure. [source]

COOKING BEHAVIOR OF RICE AND BLACK GRAM IN THE PREPARATION OF IDLI, A TRADITIONAL FERMENTED PRODUCT OF INDIAN ORIGIN, BY VISCOGRAPHY

JOURNAL OF TEXTURE STUDIES, Issue 1 2009
BONG KYUNG KOH
ABSTRACT Pasting profile of coarse rice, fine rice as well as black gram was carried out individually, in combination, in flour as well as in batter form, before and after fermentation by Brabender Viscoamylograph. Lowest gelatinization temperature was seen in black gram among the three commodities studied. Coarse rice registered a peak viscosity (PV) of 1,300 BU, fine rice 1,030 BU and black gram 1,080 BU. Cold paste viscosity (CPV) was highest in fine rice, lowest in black gram and intermediate in coarse rice. Breakdown (BD) was least in fine rice, highest in coarse rice and black gram lay in between. Values of total setback indicated the strong reason for use of coarse rice in parboiling as well as in idli and dosa preparations. Physical combination of black gram, with fine as well as coarse rice, reduced PV on an average to an extent of 26,30%. CPV was highest in fine rice and black gram combination compared with that of coarse rice and black gram. BD was high in the physical mix of coarse rice and black gram. In comparison with physical mix of fine rice and black gram, in the batter form before fermentation, the PV and CPV reduced by 23 and 34%, respectively, but there was no BD in this mix, indicating restricted swelling behavior in the batter before fermentation. Almost all viscographic parameters reduced before fermentation in coarse rice and black gram compared with their physical combination. Highest relative BD (BDr) was noticed in the pasting profile of black gram alone, probably because of the presence of mucilaginous principle. BDr values increased in batter form to various extents, before and after fermentation, compared with physical combination of rice and black gram. After fermentation, in coarse rice and black gram, the BDr value was low compared with that in fine rice and black gram. PRACTICAL APPLICATIONS Fermented products are commonly ingested in India, especially in the southern states. Nowadays, batter is sold in public for the sake of convenience, as it is a common breakfast preparation. The practice is to use coarse rice for the preparation of idli, a steamed fermented product. It is generally not known how the rice behaves before and after fermentation while cooking. Hence, this work was planned, and results indicated the scientific basis for the usage of coarse rice in the preparation of rice products. The behavior of batter prepared from fine rice has also been described, although it is not an economically viable option. [source]

Gelatinization temperature of rice explained by polymorphisms in starch synthase

Ultrasound pretreatment of cassava chip slurry to enhance sugar release for subsequent ethanol production

BIOTECHNOLOGY & BIOENGINEERING, Issue 3 2008
Saoharit Nitayavardhana
Abstract The use of ultrasound pretreatment to enhance liquefaction and saccharification of cassava chips was investigated. Cassava chip slurry samples were subjected to sonication for 10,40 s at three power levels of low (2 W/mL), medium (5 W/mL), and high (8 W/mL). The samples were simultaneously exposed to enzymes to convert starch into glucose. The cassava particle size declined nearly 40-fold following ultrasonic pretreatment at high power input. Scanning electron micrographs of both unsonicated (control) and sonicated samples showed disruption of fibrous material in cassava chips but did not affect the granular structure of starch. Reducing sugar release improved in direct proportion to the power input and sonication time. The reducing sugar increase was as much as 180% with respect to the control groups. The slurry samples with enzyme addition during sonication resulted in better reducing sugar release than the samples with enzyme addition after sonication. The heat generated during sonication below starch gelatinization temperature apparently had no effect on the reducing sugar release. The reducing sugar yield and energy efficiency of ultrasound pretreated samples increased with total solids (TS) contents. The highest reducing sugar yield of 22 g/100 g of sample and efficiency of 323% were obtained for cassava slurry with 25% TS at high power. The reducing sugar yield at the completion of reaction (R,) were over twofold higher compared to the control groups. The integration of ultrasound into a cassava-based ethanol plant may significantly improve the overall ethanol yield. Biotechnol. Bioeng. 2008;101: 487,496. © 2008 Wiley Periodicals, Inc. [source]