• 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.16 no.2
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• pp.185-191
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• 1984

The structure and textural properties of the traditional starch gel-form food Mook were investigated with the use of the Scanning Electron Microscope and Instron universal testing machine. Sensory evaluation was undertaken to evaluate the relationship between structure and textural properties of starch gel. When pure mungbean, potato, and sweet potato starches as well as 30% mungbean starches added to potato and to sweet potato starches were evaluated, it was found that mungbean starch gel had homogeneous and porous structure and showed the highest acceptability.

• Korean Journal of Microbiology
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• v.10 no.2
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• pp.79-86
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• 1972

The possibility of substituting potato or sweet potato for the wheat, one of the raw materials for soy sauce, was studied by measuring the amylase and proteolytic activities of Koji. Also optimum conditions of Koji making were determined. It was found that substitution of up to 30% (starch content) of wheat content (15% of the total bean and wheat content) with potato yielded good qulity of soy sauce. Use of more than 30% potato yielded a Koji of low enzymatic activity. This was attributed to the high moisture content of potato. It ws also found that substitution of up to 50% (starch content) of wheat content(25% of the total bean and wheat content) with sweet potato yieldede a good quality of soy sauce. But the taste was inferior to the control (the soy sauce which was made with 50% of bean and 50% of wheat).

• Food Science and Biotechnology
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• v.17 no.4
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• pp.705-712
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• 2008

Sweet potato starch was modified using Thermus aquaticus $\alpha$-1,4-glucanotransferase ($Ta{\alpha}GT$), and its structural and rheological properties were investigated. $Ta{\alpha}GT$-modified starch had a lower amylose level and molecular weight than raw starch. The chain length distribution showed an increased number of short and long branched chains and the formation of cycloamyloses. Compared with raw starch, $Ta{\alpha}GT$-modified starch displayed a lower gelatinization enthalpy and a wider melting temperature range. The X-ray diffraction of $Ta{\alpha}GT$-modified starch was a weak V-type pattern with distinct sharp peaks at 13 and $20^{\circ}$. Scanning electron micrographs of modified starch exhibited big holes on the surface and the loss of granular structure. The frequency sweep measurement revealed that the gel of $Ta{\alpha}GT$-modified starch was more rigid than raw starch gel. However, the structure of modified starch gel was destroyed by heating at $75^{\circ}C$, and a firm gel was re-formed by subsequent storage at $5^{\circ}C$, indicating thermoreversible property.

• The Korean Journal of Food And Nutrition
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• v.3 no.1
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• pp.1-8
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• 1990

Experiments were performed using sweet potato starch-wheat composite flours to study the rheology and baking properties of bread with composite flours and to test sensory characteristics. Doughs were prepared from mixtures containing wheat flour and 10, 20, and 30% of sweet potato starch(SPS). Standard methods were used to evaluate the rheology and characteristics of wheat composite flour.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.60-65
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• 2001

Physicochemical properties of 4 kinds of domestic and 7 kinds of foreign starch vermicelli (1 from Chinese, 6 from Japan) were determined. Peak temperature of starch vermicelli measured by DSC were $42{\sim}48^{\circ}C$ which were much lower than gelatinization temperatures of their raw material starches. X-ray diffraction peaks of starch vermicelli were not sharp compared with those of raw material starches which indicated that starches were gelatinized by heating and retrograded by cooling and freezing during production of starch vermicelli. Hardness and compression slope of sweet potato starch vermicelli measured by rheometer were respectively $9,500{\sim}11,000\;g/cm^2$ and $18,000{\sim}26,000\;g/cm^2$ which were twice higher than those of corn starch vermicelli. Cooking loss of corn starch vermicelli, which was 19.8%, was higher than that of sweet potato starch vermicelli, $4.2{\sim}6.6%$ and mung bean starch vermicelli, 7.7%. In changes of thickness of starch vermicelli during cooking i.e swelling ratio, sweet potato starch vermicelli had $58{\sim}69%$ of swelling ratio, which was higher than that of corn starch vermicelli, 50%. Corn starch vermicelli, which was relatively less elastic and easily broken, was shown to be inferior to that of sweet potato starch vermicelli in overall quality.

• Preventive Nutrition and Food Science
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• v.13 no.3
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• pp.249-252
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• 2008

Flow behaviors of sweet potato starch (SPS) pastes (5% w/w) were studied in the presence of various sugars (xylose, glucose, fructose and sucrose) and sugar alcohols (xylitol and sorbitol). The flow properties of SPS-sugar mixtures were determined from the rheological parameters of power law model. The vane method was also employed for determining yield stresses of SPS-sugar mixtures directly under a controlled low shear rate. At $25^{\circ}C$ all the samples showed shear-thinning behaviors ($n=0.35{\sim}0.44$) with yield stress. The consistency index (K) values of SPS-sugar mixtures increased in the following order: sorbitol> xylitol> control (no sugar)> sucrose> fructose> glucose> xylose, showing that the addition of sugar alcohols enhanced the K values. The yield stress values were reduced in the presence of ugars and sugar alcohols and they also increased with an increase in swelling power of starch granules in the SPS-sugar mixture systems.

• Korean Journal of Pharmacognosy
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• v.17 no.2
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• pp.134-138
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• 1986

Based on a tracer study, starch phosphorylase was implicated as an agent in the starch synthesis in sweet potato roots. The enzyme was purified from the tissue as a cluster of isozymes with an average mw of 205K (fresh roots) or 159K (roots stored for 3 mon.). On SDS polyacrylamide gel electrophoresis, one large subunit of 98K mw and several small ones of 47${\sim}57K mw were observed. From the mw data and the results of peptide mapping and immunoelectrophoretic blotting using mono- and polyclonal antibodies, it was deduced that a large part of the large subunit was cleaved at the middle part of the peptide chain to give rise to the small subunits, and on storage, the enzyme molecules were further modified by proteolysis. During the course of phosphorylase purification, a proteinaceous inhibitor of the enzyme was isolated. It had a mw of 250K and was composed of 5 identical subunits of 51K mw. In the direction of starch synthesis, the inhibitor showed a noncompetitive kinetics with a Ki of $1.3{\times}10^{-6}\;M$. By immunohistochemical methods, both the enzyme and the inhibitor were located on the cell wall and amyloplast. Crossreacting materials of the inhibitor were present in spinach leaf, potato tuber and rice grain. These findings indicate the wide occurrence of the inhibitor and also imply its possible participation in regulating starch phosphorylase activity in vivo.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.39-39
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• 2017

In Asia, sweet potato (Ipomoea batatas) is a very important crop for starch production. Approximately 74.3% of the total sweet potato production quantity is produced in Asia (FAO, 2014) and China is the largest producer of sweet potato. Post-harvest management is particularly important because it is difficult to maintain the quality as well as quantity of sweet potatoes. Despite the importance of post-harvest management, researches on sweet potato have been focused on production-related study such as breeding of new variety, improved techniques of cultivation, so there is limited research on storage after harvest. Curing is a normal practice after sweet potato harvest to promote wound healing and extend postharvest storage life. In Korea, harvested sweet potatoes are usually cured for 4 to 7 days at $30-33^{\circ}C$ and 80-95% relative humidity within one week. Since the optimum storage temperature of sweet potato is regarded as $15-20^{\circ}C$, additional facilities and costs are required to raise the temperature for curing. However, the majority of small farmers do not have the capacity to provide additional facilities and costs. This study was initiated to suggest a new curing method to accelerate the wound healing by applying chemical oxidation to the wound surface of sweet potato. Oxidative stress is known to play an important role in the synthesis of secondary metabolites including lignin. In addition, chemical oxidation can be applied to prevent spoilage caused by microorganisms. Powerful gaseous oxidant with excellent penetration ability and superior sterilization effect was selected for this study. Lignification, weight loss, and spoilage rate of artificially wounded sweet potatoes were investigated after oxidant fumigation. There were clear differences in morphological analysis such as lignification pattern, lignin deposition color, and continuity of lignified cell layers between oxidant-fumigated sweet potatoes and control. These results show that gaseous oxidant can be used to supplement or replace the curing practice, to improve shelf-life as well as curing cost reduction.

• Korean journal of food and cookery science
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• v.8 no.3
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• pp.255-263
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• 1992

Pasting characteristics and amylose-surfactant complex forming ability of sweet potato starch were investigated after defatting and the addition of surfactants, such as SSL (sodium steamyl-2-lactylate) Dimodan (mono/di glyceride) and SE (sucrose ester) with different concentrations. All starch granules were smooth and round, there were no damages to starch granules after defatting and surfactant addition. amylose content of surfactant added stach decreased and me order of decrease was SSL, SE and Dimodan. The cornplex forming ability of SE added starch increased according to increasing HLB value. As surfactants concentration increased, amylose complex formig ability increased. In case of gelatinization patterns by amylograph, the initial pasting temperature of surfactant added starches was higher than mat of untreated or defatted starches, but viscosity at each temperature were all decreased. Soluble carbohydrate and leached amylose of starches increased at increasing temperature, those of surfactant added starches decreased at each temperature in the order of SSL, SE and Dimodan.