• Korean Journal of Food Science and Technology
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• v.46 no.2
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• pp.135-142
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• 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
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• v.31 no.1
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• pp.62-67
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• 1999

Periodate-oxidized soluble starch and maltohexaose, maltotetraose, maltose, and glyceraldehyde reacted with sweet potato ${\beta}-amylase$, wheat ${\beta}-amylase$, aldolase, bovine serum albumin, catalase, carboxypeptidase, ferritin and pronase. Electrophoretical mobility of modified proteins was different from that of native proteins, and modified proteins were stained with periodic acid-Schiff while native proteins did not stain. This results means that oxidized sugars attached on proteins. This bond is based on the Schiffs base between CHO group of oxidized sugar and ${\varepsilon}-NH_2$ group of lysine of protein. There is no changed UV absorption spectrum of sweet potato ${\beta}-amylase$ modified with oxidized soluble starch, in comparison with native enzyme.

• The Korean Journal of Food And Nutrition
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• v.3 no.2
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• pp.123-132
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• 1990

Sweet potato $\beta$-amylase is a tetrameric enzyme consisting of four identical polypeptide chains with a molecular weight of 5.6$\times$104, though most of the other $\beta$-amylases are monomeric enzymes. But, the relationship between subunit structure and catalytic function of the enzyme is not known. This study was done to know what the function of the subunit structure of the enzyme is. We obtained the monomer from the enzyme by the treatment of SDS, alkali pH buffer and urea. But the monomer had not activity. We tried to prepare the active monomer from the enzyme by the modification with periodate-oxidized soluble starch , In the result, we succeeded in isolating an active monomer as an oxidized soluble starch-conjugated form The active monomer had 57% of the original activity, 13.2% of the sugar and the molecular weight was estimated to be 5.4$\times$104. This results suggest that the tetrameric form of the enzyme is a most stable one and exists in nature, and the subunit structure of the enzyme Plays an important role in stabilization but not catalytic function.

• The Korean Journal of Food And Nutrition
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• v.30 no.4
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• pp.689-695
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• 2017

Ohmic heating is an internal heating method based on the principle that when an electrical current passes through food, electric resistance heat is uniformly generated internally by food resistance. Previous studies indicate that the thermal properties, external structure, internal structure, and swelling power of ohmic heat treated starch of various starches, such as potato, wheat, corn, and sweet potato, differed from those of conventional heating at the same temperature. In this study, the pasting property of starch, treated with ohmic and conventional heating, were measured by RVA (Rapid Visco-Analyzer). Our results show that as the ohmic heating temperature increased, the PV (Paste Viscosity) of the starch decreased significantly, and the PT (Pasting Temperature) increased. Changes in PV and PT indicate that the swelling of starch remains unchanged by ohm heating. The HPV (Hot Paste Viscosity), CPV (Cold Paste Viscosity) and SV (Setback Viscosity) of ohmic heated starch also differed from the conventional heated starch. The pasting property is similar to the viscosity curve of common cross-linked modified starch. In this experiment, we further confirm the similarity with modified starch and its usability.

• Korean Journal of Food Science and Technology
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• v.17 no.4
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• pp.258-264
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• 1985

The energy for cooking starch prior to saccharification could be saved by fermenting raw starch into ethanol using Aspergillus niger koji of wheat bran. Optimum cultivation time to produce glucoamylase was 4 days in wheat bran medium. The rate of saccharification from uncooked corn starch were optimum at pH 3.3 and 40-$50^{\circ}C$. Corn and sweet potato starch were saccharified more efficiently by wheat bran koji than other tested starch sources. 5 days of fermentation were required for optimum yield of ethanol using a mixture of AspergiUus niger koji and dried yeast. Final ethanol yields from raw corn, sweet potato, and rice starch with agitation at the rate of 100 rpm were about 95% at $30^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.10 no.4
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• pp.423-430
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• 1978

Since 1950 there has been a dramatic progress in rationalization of the production of sweet potato and potato starch in Japan. This enabled dextrose industry by enzymatic process to develop rapidly due to the success of enzymatic liquefaction and saccharification. Isomerization of glucose to fructose has been studied, and the immobilization of isomerases prompted its products on industrial scale in 1970. Another advance is the development of effective methods of producing high purity maltose. A malto-hexaose forming amylase was discovered in 1971 and attempts are being made for its pharmaceutical utilization. Saccharification of cellulose by cellulase has been studied. Conversion of starch to other polysaccharides is another example for the numerous Japanese activities.

• Journal of the Korean Society of Food Science and Nutrition
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• v.30 no.6
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• pp.1082-1087
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• 2001

A study was carried out to establish the detection method for irradiated cereals. Starchs were ground and irradiated at 2.5, 5.0, 7.5, 10 and 15 kGy using a Co-60 irradiator. The viscosities decreased in all samples by increasing irradiation dose. The viscosity of the potato, corn and sweet potato from Korea dropped from 35.00$\pm$ 0.34, 11.86$\pm$0.86 and 14.02$\pm$0.62 in the control to 11.38$\pm$0.92, 2.98$\pm$0.80 and 2.74$\pm$0.80, respectively, in the samples irradiated at 15 kGy. These trends were similar to samples from China. Regression expression and coefficients of viscosity of potato, corn and sweet potato starch from Korea were 0.97 (y=-4.6197x+38.284), 0.88 (y=-1.5146x+12.023) and 0.88 (y=-1.5146x+12.023), respectively, those of viscosity of starches from China were 0.69 (y=-28.849x+152.25), 0.81 (y=-3.38x+20.56) and 0.88 (y=-2.668x+18.505) at 50 rpm. All samples resulted in a decrease in specific parameter by increasing rpm after irradiation. Parameter values showed dose-dependent relationship between unirradiated and irradiated samples and indicated that all values of unirradiated samples were higher than the those of irradiated ones. These results suggest that the detection of irradiated potato, corn and sweet potato starch at various irradiation doses is possible by the viscometric method.

• Applied Biological Chemistry
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• v.24 no.2
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• pp.120-125
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• 1981

Organic acids of Kochuzang (red pepper paste) prepared from glutinous rice, polished barley, wheat flour and sweet potato were analyzed by a gas chromatography. Lactic, pyruvic, succinic, fumaric, malic, pyroglutamic and citric acid were identified. And trace amount of oxalic acid was found in the Kochuzang prepared from sweet potato. The dominant organic acid of all samples was pyroglutamic acid, followed by pyruvic and citric acid. The organic acids were lower in Kochuzang from wheat flour than in other samples. The contents of succinic and fumaric acid were highest in Kochuzang prepared from sweet potato and were lowest in polished barley Kochuzang.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.6
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• pp.861-868
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• 2012

During two years, four samples per year were collected in Vietnam from rice bran, cassava residue, brewer's grain, tofu residue, soybean meal, coconut cake, sweet potato vines and water spinach for chemical analysis and assessment of water holding capacity (WHC). The selected feedstuffs represent fibre-rich plant sources and agro-industry co-products commonly used in pig feeding in Vietnam. The content (g/kg DM) of crude protein (CP), ether extract (EE) and non-starch polysaccharides (NSP) varied between feedstuffs and ranged from 21 to 506 for CP, from 14 to 118 for EE and from 197 to 572 for NSP. Cassava residue had a high starch content of 563 g/kg DM, while sweet potato vines, water spinach, coconut cake and soybean meal had a high content of sugars (63-71 g/kg DM). The content of individual neutral sugars varied between feed ingredients, with the highest content of arabinose, galactose and glucose in tofu residue, the highest content of xylose in brewer's grain and the highest content of mannose in coconut cake. The content of uronic acid was high for cassava residue, tofu residue, sweet potato vines and water spinach (57-88 g/kg DM). The content of soluble non-cellulosic polysaccharides (S-NCP) was positively correlated ($r^2$ = 0.82) to the WHC. The content (g/kg DM) of CP, NDF, neutral sugars, total NSP, total NCP, S-NCP and total dietary fibre in tofu residue, water spinach and coconut cake varied (p<0.05) between years. In conclusion, diet formulation to pigs can be improved if the variation in chemical composition of the fibre fraction and in WHC between potential feed ingredients is taken into account.

• 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.