• Korean Journal of Food Science and Technology
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• v.20 no.3
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• pp.412-418
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• 1988

Granular shapes and sizes, physicochemical priperties and gelatinization patterns of sweet potato starches from Wonki(the dry type) and Chunmi(the moist type) were investigated. Starch granules of sweet potatoes were round. Granule sizes of Wonki starch were mainly $11{\mu}m$ and those of Chunmi starch were $12{\mu}m\;and\;17{\mu}m$. Wonki starch had lower water binding capacity and swelling power than Chunmi starch. But Wonki starch had higher amylose content, gelatinization temperature, miture content for gelatinization and temperature for gelatinization than Chunmi starch.

• Korean Journal of Food Science and Technology
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• v.32 no.4
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• pp.834-842
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• 2000

In order to investigate the characteristics of various sweet potato starches, gelatinization temperatures, solution viscosity of starch separated from two cultivars of the dry type sweet potatoes(Yulmi and Gunmi), one cultivar of moist type sweet potato(Jinmi), and one cultivar of purple colored variety(Jami) were compared, and properties of the edible films prepared with the starches were determined. Under a differential scanning colorimetry(DSC), initial temperatures for starch gelatinization of the dry type sweet potatoes (Yulmi and Gunmi) were higher than that of the moist type sweet potato (Jinmi), and that of Jami was close to those of the dry type ones. The sweet potato starch solutions tested by a cone and plate viscometer, showed peudoplastic characteristics. The moist type sweet potato was the most viscous followed by Jami, Yulmi, and Gunmi among the tested starch solutions. Total color difference of the edible films prepared with different cultivars of sweet potatoes showed appreciable differences between cultivars, caused by differences in Hunterb values. Water Vapor Permeability (WVP) of sweet potato starch films also showed significant differences between cultivars. Films prepared with the dry type sweet potato, Gunmi, showed the lowest WVP value of $0.83{\times}10^{-9}\;g\;{\cdot}\;m/m^{2}\;{\cdot}\;s\;{\cdot}\;Pa$, followed by Jami, Yulmi, and Jinmi. Water solubility of the films did not show any significant differences between cultivars. Tensile strength of the dry type sweet potato and Jami, which ranged 14.18-18.75 MPa, were higher than that of the moist type sweet potato, which was 4.66 MPa. Elongation values of the films, which were 5-6%, indicated that sweet potato starch films were not so elastic.

• Korean journal of food and cookery science
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• v.27 no.2
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• pp.19-29
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• 2011

Sweet potato powders made from eight Korean varieties, including purple-fleshed, orange-fleshed, and commercial dry type sweet potatoes, were investigated for physicochemical and pasting properties to develop processed food. Crude protein and lipid contents of Shinjami and Borami were higher than those of other varieties. The lightness value of raw sweet potato flesh was the highest value in Shinchunmi, and the lowest in Shinjami. Using the color difference (${\Delta}E$), color similarities compared to the white plate occurred in the following order; purple-fleshed > orange-fleshed > commercial dry type sweet potatoes. Total and damaged starch contents were significantly different (p<0.05). Total starch content of sweet potatoes was higher in commercial dry sweet potatoes (61.89-70.46%), particularly Shinchunmi (70.46%) but lower in orange-fleshed sweet potato (48.87 and 49.53%, respectively). Water binding capacity of Yeonwhangmi, swelling power and solubility of Shinyulmi were the highest values (174.70, 25.54 and 87.49%, respectively) among them (p<0.05). But oil absorptions of Shinyulmi and Shinchunmi showed lower values (97.08 and 97.54%, respectively). All sweet potato powders had an A type x-ray diffraction pattern. The initial pasting temperatures of sweet potato powders ranged from 69.50 to $75.95^{\circ}C$ and the amylolytic enzyme in sweet potato powder lowered pasting viscosity.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.198-198
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• 2017

Cultivated varieties of sweet potato were from dry texture type to tender texture type on the basis of consumer preferences. There are many differences in the quantity of sweet potato, starch content, pigment, and sugar content depending on the cultivation season and area, even in the same variety. Therefore, in this study, we attempted to establish optimum time of harvesting through growth characteristics and variation in component like starch, sugar, polyphenol and flavonoid. Four sweet potato varieties were used in this experiment. Among them, Jinhongmi (JHM) & Yulmi (YM) were as dry texture type and Pungwonmi (PWM) & Hogammi (HGM) were as tender texture type. Sweet potatoes were transplanted on 23 May, 2016 and were investigated storage root weight and component contents every 20 days from 60 days to 120 days and surveyed yield at 110, 120, 130 days after transplantation. Result revealed that storage root weight of YM, JHM, and HGM were 30.1, 38.9, 20.8 g respectively in 60 days after transplanting. Storage roots of PWM gerw faster with the weight of 88.2 g. In 120 days after transplanting, storage root weight varied from 88.3 to 118.7 g, HGM was the smallest, and PWM was the largest. Sugar contents of sweet potato ranged from 21.0 to $23.8Brix^{\circ}$ in 60 days after transplanting and from 27.5 to $30.78Brix^{\circ}$ in 120 days after transplanting. In particular, the sugar content of HGM was the highest over $30Brix^{\circ}$ after 80 days. The starch content of dry texture type (YM, JHM) increased from 15.5% to 20.4% and tender texture type (PWM, HGM) increased from 11.0% to 17.3%. Starch content tended to be high in dry type sweet potatoes. The content of polyphenol and flavonoid were highest in 60 days after transplanting and was reduced according to cultivation period. The total yield of PWM was high as 3,154 kg/10a and large storage root of over 250 g accounted for 47.4% in 110 days after transplanting. Storage root (YM, JHM, HGM) of 81~150 g accounted for 34.9% ~ 43.2% in 120 days after transplanting. These are the most marketable. Because consumer in Korea prefers small, round and about 100g size sweet potato. The ratio of large storage root (over 250 g) were increased in all varieties at 130 days after transplanting. Therefore, it is considered appropriate to harvest PWM at 110 days and YM, JHM, HGM at 120 days after transplanting, which planted in late May.

• Applied Biological Chemistry
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• v.30 no.4
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• pp.315-322
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• 1987

Attempts were made to unravel the differences in the textural properties between a dry type, Wonki and a moist type, Chunmi sweet potato. The changes in the ingredients, cellular shapes, degree of gelatinization and hardness of sweet potatoes during baking were studied. Alcohol insoluble solid, starch and protopectin contents and activities of amylase and polygalacturonase of Wonki sweet potato were higher than those of Chunmi sweet potato. The cell sizes were smaller and the number of starch granules within the cells were higher in Wonki than in Chunmi. Gelatinization occurred in Wonki more lately than in Chunmi during baking. The difference in hardness after baking between Wonki and Chunmi was found distinctively. But both samples were gelatinized completely, the difference in hardness was not found.

• Applied Biological Chemistry
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• v.34 no.1
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• pp.26-31
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• 1991

The physicochemical properties of starches from dry(Suwon 147) and moist type(Hwangmi) sweet potato were investigated and molecular structural properties of their amylopectins were also studied by gel chromatography. Suwon 147 starch bad lower swelling power and higher gelatinization temperature than Hwangmi starch. $\beta-Amylolysis\;limit(%)$ of Suwon 147 and Hwangmi amylopectin were 57.6% and 57.0%, respectively. Average unit chain length of amylopectins were 24.8 glucose units for Suwon 147 and 21.9 for Hwangmi. The elution profiles by Sephadex G-50 after debranched amylopectins of the two starches were similar but DPs of each peak were different.

• Applied Biological Chemistry
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• v.35 no.3
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• pp.196-201
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• 1992

Characteristics on lintnerization of dry type (Suwon 147) and moist type (Hwangmi) sweet potato starches were investigated. Chain distribution of lintnerized starches was also studied by debranching with pullulanase. Hydrolytic patterns of two starches showed two distinct stages and hydrolysis extents of Suwon 147 starch were lower than those of Hwangmi starch. The relative crystallinities of Suwon 147 starches were higher than those of Hwangmi starch. The elution profiles of lintnerized starches were composed of two peaks about degree of polymerization (DP) 25 and DP 15. The elution profiles of debranched samples showed only one peak about DP 15 and peak DP of Suwon 147 lintnerized starch was higher than that of Hwangmi.

• Korean Journal of Food Science and Technology
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• v.18 no.6
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• pp.431-436
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• 1986

The action of crude amylolytic enzymes extracted from Wonki and Chunmi sweet potatoes, ${\alpha}-amylase$, and ${\beta}-amylase$ on the sweet potato starches from Wonki (dry type) and Chunmi (moist type) were studied. The activity of crude amylolytic enzyme extracted from Wonki was higher than that extracted from Chunmi. The content of reducing sugar released from the reaction between crude amylolytic enzyme and Chunmi starch preheated at $70^{\circ}C$ was higher, but that preheated at $95^{\circ}C$ was lower than that from Wonki starch preheated at the same temperature. The activites of ${\alpha}-amylase$ and ${\beta}-amylase$ on the Wonki starch were higher than those of the Chunmi starch at the same conditions. Iodine affinity of amylolytic enzyme-treated starch was decreased and enzyme treated starch granule shape was found with porous structure having inner layers. X-ray diffraction patterns of amylolytic enzyme-treated starches were the Ca type like the intact starches and relative crystallinity was decreased.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.41 no.3
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• pp.332-339
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• 1996

Electrophoretic method was utilized to classify 100 varieties of sweet potato germplasm maintained at the National Crop Experiment Station of Korea in 1993. The esterase isozyme patterns in the leaves were classified into 14 different types. Type Ⅸ included the most of the varieties (46) tested and Ⅶ, I, III, Ⅷ, II and V types of all included 47 varieties in order. The other 7 varieties had different band pattern with each other. Type I having many kind of band pattern included Shinyulmi, Beniastma and High starch which had the dry type of tuberous roots varieties. The esterase isozymes pattern in the tuberous roots were classified with 18 kinds of types. The C type included 22 varieties and B, K, A, E, I and N in order. The proteins pattern in the tuberous roots were classified with 7 kinds of types. I type included 36 varieties, and IV type included 27 varieties and II, III, Ⅶ and Ⅵ types in order.

• Korean Journal of Food Science and Technology
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• v.23 no.3
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• pp.341-348
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• 1991

Physicochemical properties and gelatinization patterns of defatted and lipid-reintroduced moist (Hwangmi) and dry (Suwon 147) type sweet potato starches were investigated. Starch granules of sweet potato were polygonal and round, and the sizes of starch granules ranged $5{\sim}13\;{\mu}m$. All starches showed Ca type in X-ray diffraction but relative crystallinity was decreased by defatting and reintroduction. The amylose content of defatted starches increased, but that of lipid-reintroduced starches decreased. The swelling power and solubility at each temperature increased by defatting, but decreased by reintroduction. Transmittance of Hwangmi and Suwon 147 showed a rapid increase at $60,\;65^{\circ}C$, respectively. The initial pasting temperature by amylograph of Hwangmi and Suwon 147 were $67.5^{\circ}C\;and\;72.7^{\circ}C$, respectively. The peak viscosity and the height at $50^{\circ}C$ on amylogram of Hwangmi were lower than those of Suwon 147. Hot paste viscosity and setback decreased by defatting but setbak and consistency drastically increased by reintroduction. The peak temperature for gelatinization by the DSC was $65.7^{\circ}C$ for Hwangmi and $68.5^{\circ}C$ for Suwon 147. The gelatinization temperature and enthalpy of the DSC decreased and amylose-lipid melting peak was lost by defatting. The gelatinization temperature and enthalpy decreased by reintroduction.