• Applied Biological Chemistry
• /
• v.28 no.1
• /
• pp.19-27
• /
• 1985

The physicochemical properties of starch isolated from Yullmoo (Coix lachrymajobi var. mayuen stapf.) and Yeomjoo (Coix lachryma-jobi L.) were investigated. The average diameters of starch granules of Yullmoo and Yeomjoo were 12.0 microns, both of all, and the shape of these starch granules were hexagon, octagon and round. X-ray diffraction patterns of two samples were A-types and amylose contents of Yullmoo and Yeomjoo starch were 0% and 23%, respectively, iodine affinities of these were 0.08% and 4.2%, respectively, blue values and alkali numbers of these were 0.13 and 0.43, 2.4 and 7.2, and raising power of these were 280 and 20, respectively. Yullmoo starch had higher swelling power than Yeomjoo starch. The increase in optical transmittance of 0.1% suspensions of Yullmoo and Yeomjoo starches occurred at $60^{\circ}C$ and continued up to $75^{\circ}C$ for Yullmoo, $85^{\circ}C$ for Yeomjoo. Amylogram data on 5% of Yullmoo and Yeomjoo starch suspensions showed that gelatinization temperatures and maximum peak heights of Yullmoo and Yeomjoo were $68.5^{\circ}C\;and\;78^{\circ}C$, 920 and 310 B.U., respectiyely. Intrinsic viscosities of Yullmoo and Yeomjoo starches were 1.49 and 1.77, respectively, and interaction coefficients of the two starches were 0.57 and 0.56, respectively The extent of retrogradation determined at $2^{\circ}C$ showed that retrogradation occurred slowly with Yullmoo starch paste tut little with Yullmoo.

• Food Science and Preservation
• /
• v.13 no.3
• /
• pp.382-388
• /
• 2006

Physicochemical properties of chufa starch were investigated The result are summarized as follow: Moisture content crude protein and crude fat were 10.10%, 0.31% and 0.41,% respectively. Amylose content of chufa starch was 41.6% and blue value was 0.49. Lightness and whiteness of chufa starch was 96.36 and 92.23 of Hunter's color value. In iodine reaction, maximum absorbance wavelength (${\lambda}max$) was 628 nm. Water binding capacity was 83% and swelling power and solubility of chufa starch were increased slowly to $60^{\circ}C$, but increased rapidly after $60^{\circ}C$. Scanning election microscope(SEM) showed that granule type of chufa starch was round or elliptic type, and average granule size was $10{\mu}m$. The results by differential scanning calorimetry(DSC) revealed that gelatinization patterns were similar to those of potato or rice starch. In rapid viscoanalyzer(RVA) examination, pasting temperature was $79.95^{\circ}C$ and peak viscosity of chufa starch was 385.08.

• Korean Journal of Food Science and Technology
• /
• v.21 no.6
• /
• pp.766-771
• /
• 1989

physicochemical properties of rice starch isolated from eight varieties were examined to evaluate the rice processing suitability The amylose contents of rice starch were varied with 16.7-29.7%, and IR 30, Godael, Aguja and Lengkwang varieties showed higher amylose content than the other varieties. The water binding capacity and blue value were in the range of 87.0 103.0 and 0.178-0.305, respectively. As the amylose content increased, the amylogram pasting temperature and the break down ratio increased, while the peak viscosity did not show any significant difference. The transmittance of 0.1% starch suspension slowly increased at $50^{\circ}C$ in the low-amylose content rice group, and rapidly increased at $65^{\circ}C$ in the high-amylose content rice group, but there were no differences above $75^{\circ}C$ among varieties. Also the low-amylose rice starch showed higher values in the swelling power and solubility. The hardness of the 30% rice starch gels was low in low-amylose one. During storage at $20^{\circ}C$ for 14 days, the increment of hardness was more slow in high-amylose one. The retrogradation velocity constant of rice starch gel by Avrami equation was the highest as 0.219 in Aguja variety.

• Korean Journal of Food Science and Technology
• /
• v.46 no.2
• /
• pp.135-142
• /
• 2014

Physicochemical, pasting, and digestion properties of sweet potato starches from 11 Korean cultivars were investigated. Starch granules were variably oval, round, polygonal, spherical, and bell-shaped, and of 10.2-15.3 ${\mu}m$ in mean particle diameter. Amylose contents varied from 12.3 to 17.4%. A similar chain length distribution of amylopectin was found in each of the cultivars. The portion of $B_3$ correlated with the degree of amylose leaching. Thermal properties determined by differential scanning calorimetry showed high values of gelatinization temperatures in Shinyulmi and Jeungmi starches, but a relatively low value in Daeyumi starch. All starches exhibited a Ca-type diffraction pattern. Differing patterns were observed in swelling factors, depending on temperature. The contents of rapidly digestible starch, slowly digestible starch, and resistant starch ranged from 9.6-17.4, 31.4-45.6, and 35.7-62.8%, respectively. In Rapid Visco Analyser profiles, differences were observed in pasting parameters such as pasting temperature, peak viscosity, final viscosity, and breakdown.

• Korean Journal of Food Science and Technology
• /
• v.51 no.2
• /
• pp.109-113
• /
• 2019

The soft rice varieties, Hangaru and Singil, were developed via mutation breeding using N-methyl-N-nitrosourea treatment to obtain dry-milled rice flours. The physicochemical, morphological, and pasting properties of these starches were compared with those of Seolgaeng and Chuchung starches. Singil starch was found to exhibit the highest amylose content and initial pasting temperature, whereas Hangaru starch exhibited the highest water binding capacity and swelling power. Hangaru starch's granule size at $d_{50}$ was the largest among the four different starch types. Some Seolgaeng, Hangaru, and Singil granules were observed to have a round-faced polygon shape. Furthermore, the crystallinity of all four starch types was type A. The peak, trough, and final viscosities of the soft rice starches were also lower than those of normal starches. Notably, Hangaru starch showed the highest breakdown viscosity, but the lowest total setback viscosity among the four starches. From these results, the starch characteristics of the soft rice flours were discovered to be different based on the rice variety.

• Applied Biological Chemistry
• /
• v.39 no.1
• /
• pp.49-53
• /
• 1996

Acid-modified starch was prepared by treating a warm aqueous starch suspension with dilute mineral acid$(0.2\;N\;HCl,\;45^{\circ}C,\;20\;mim{\sim}1\;h)$. The swelling power and solubility of acid-modified red bean starches increased and the changes occurred at tower temperature. According to gel chromatography of starches, the amylose and amylopectin moieties of red bean starches were not affected very much by hydrolysis conditions used. The elution profiles of soluble carbohydrate showed that the larger molecules were leached as the heating temperature increased. Total amounts of soluble carbohydrate were increased by acid-modification. The gel strength of acid-modified starches at each temperature increased, whereas cohesiveness decreased in acid-modified starch gels except at $85^{\circ}C$.

• Korean Journal of Food Science and Technology
• /
• v.27 no.4
• /
• pp.532-536
• /
• 1995

Effect of water activity $(0.32{\sim}0.89)$ on the physicochemical properties of sweet potato starch during the storage for 5, 15 and 30 days at $40^{\circ}C$ was investigated. Shapes and sizes of starch granules were not changed. X-ray diffraction patterns of the starches appeared equally Ca-crystal structure. Sorption isotherm with storage day was sigmoidal. A slight loss of iodine affinity, increase in water binding capacity, and decrease in swelling power at $80^{\circ}C$ occurred as water activities increased. Viscosity pattern under Brabender Amylogram was not significantly changed with water activity, but initial pasting temperature decreased as water activity increased. The viscosity at $50^{\circ}C$, consistency and setback were increased with increasing storage day and water activity.

• Korean Journal of Food Science and Technology
• /
• v.19 no.1
• /
• pp.12-17
• /
• 1987

Physicochemical properties and gelatinization kinetics of Ol barley starch were studied. The granule size was $13-28\;{\mu}$ and the granule shape was oval or circular. Also, Ol barley starch had amylose content of 32%. Swelling power and solubility reached to the maximum values of 7.22 and 2.28% at the gelatinization temperature of $90^{\circ}C$. The pasting temperature of starch was slightly higher than those of powder and defatted powder. Most of the increase in light penetration was accomplished from the gelatinization temperature of $80^{\circ}C$ to $90^{\circ}C$. The gelatinization reaction of lL barley starch occurred in 2 stages. The activation energy of lst stage gelatinization reaction was 23.84 kcal/mole, whereas activation energies of 2nd stage gelatinization reaction were 33.38 and 72.82 kcal/mole around $80^{\circ}C$.

• Korean Journal of Food Science and Technology
• /
• v.39 no.5
• /
• pp.534-540
• /
• 2007

In this study, waxy rice starch was chemically modified using phosphorous oxychloride ($POCl_3$, 0.002-0.008%). Then the physicochemical properties of resulting cross-linked waxy rice starches were investigated in order to reduce the steeping time of Yukwa (a Korean oil-puffed rice snack) processing. The swelling powers of the cross-linked waxy rice starch samples were higher than the native waxy rice starch at temperatures above $60^{\circ}C$, and their increases were proportional to the $POCl_3$, concentration. The solubility of the cross-linked waxy rice starch was lower (1.6-3.4%) than the native waxy rice starch (2.7-6.1%). However, the moisture sorption isotherm of the cross-linked waxy rice starch was not significantly different from the native waxy rice starch. The rapid visco analyze. (RVA) pasting temperatures $(65.4-67^{\circ}C)$ of the cross-linked waxy rice starch were lower than those of the native starch $(67^{\circ}C)$. The RVA peak viscosities (287-337 RVU) of the cross-linked waxy rice starch were higher than that of native starch (179 rapid visco units (RVU)), and increased with increasing $POCl_3$ concentration. For the differential scornning calorimeter thermal characteristics, although Tc shifted toward higher temperatures with cross-linking, the To, Tp, and amylopectiin melting enthalpy of the cross-linked waxy rice starch showed no differences compared to the native waxy rice starch. The X-ray diffraction patterns of both the native and cross-linked waxy rice starches showed typical A-type crystal patterns, suggesting that cross-linking mainly occurs in the amorphous regions of starch granules. Therefore, the cross-linking reaction did not change the crystalline region, but altered the amorphous region of the waxy rice starch molecules, resulting in changes of solubility and RVA pasting properties in the cross-linked waxy rice starch. In summary, since cross-linked waxy rice starch has a high puffing efficiency and no browning reaction, it may be applicable for Yukwa processing without a long steeping process.

• Korean journal of food and cookery science
• /
• v.5 no.2
• /
• pp.1-8
• /
• 1989

The physicochemical properties and gel forming properties of mungbean and buckwheat crude starches were investigated. The results were as follows; 1. The granule size and shape of mungbean crude starch were $11~32\mu\textrm{m}$ and oval, and those of buckwheat crude starch were $3~10 \mu\textrm{m}$ and polygonal. 2. The amylose conteut of mungbean crude starch and buckwheat crude starch were 78.0% and 26.4% respectively. 3. The blue value of mungbean crude starch and buckwheat crude starch were 1.030 and 0.409, respectively. 4. Periodate oxidation of mungbean crude starch resulted that amylose had the average molecular weight of 95, 648, degree of polymerization of 590 and amylopectin had the degree of branching of 5.4, glucose unit per segment of 18.6, and periodate oxidation of buckwheat crude starch resulted that amylose had the average molecular weight of 133, 690, degree of polymerization of 825 and amylopectin had the degree of branching of 5.2, glucose unit per segment of 19.2 5. Water binding capacity of mungbean crude starch was 185.1% and that of buckwheat was 209.9% 6. The pattern of change in swelling power of mungbean crude starch for increasing temperature started to increase at $60^{\circ}C$ and increased rapidly from $70^{\circ}C$, and that of buckwheat increased slowly from $60^{\circ}C$ to $90^{\circ}C$ without rapid increase. 7 The ranges of gelatinization temp. of mungbean and buckwheat crude starches were 63. 9-$109^{\circ}C$ and 52.5-84.$2^{\circ}C$, respectively. 8. The gelatinization patterns for 6% munbean crude starch and 8% buckwheat crude starch were investigated by Brabender amglograph. Mungbean crude starch showed the initial pasting temperature of 77.6$^{\circ}C$ without peak height, and buckwheat crude starch showed that of $62.5^{\circ}C$ without peak height. In addition, sensory evaluation for sample starch gels (mungbean, buckwheat, cowpea) was done. 1. The difference of sensory characteristics for each starch gel was significant. 2. The sample starch gels were regarded as 'Mook' by pannels. 3. 74.44% of the degree of Mooklike was explained by hardness.