• Korean journal of food and cookery science
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• v.27 no.2
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• pp.73-81
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• 2011

Two kinds of steamed sweet potatoes were dried with mild hot air to improve quality, convenience and preference as a snack. Steamed sweet potatoes were dried at temperatures ranging from 35 to $65^{\circ}C$ for 12 hr, and moisture contents, colors, texture, and taste were evaluated. The lowest moisture content was 0.25% at $65^{\circ}C$. Color values (L, a, b and ${\Delta}E$) decreased with increasing drying temperature and drying time in both chestnut-sweet potatoes and pumpkin-sweet potatoes. Reducing sugars and soluble solids increased quickly at high drying temperatures. The highest hardness value for chestnut-sweet potatoes was $26.31\;kg_f /cm^2$when they were dried at $65^{\circ}C$ for 12 hrs. Springiness and cohesiveness were higher than those in chestnut-sweet potatoes. The highest taste score was for a dried chestnut-sweet potatoes at $55^{\circ}C$ for 6 hr and a dried pumpkin-sweet potatoes at 45 or $55^{\circ}C$ for 6 hr.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.107-107
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• 2017

Sweet corns are enjoyed worldwide as processed products and fresh ears. Types of sweet corn are based on the gene(s) involved. The oldest sweet corn type has a gene called "sugary (su)". Sugary-based sweet corn was typically named "sweet corn". With its relatively short shelf life and the discovery of a complementary gene, "sugary enhanced (se)", the sweet corn (su only) was rapidly replaced with another type of sweet corns, sugary enhanced sweet corn, which has recessive homozygous su/su, se/se genotype. With the incorporation of se/se genotype into existing su/su genotype, sugary enhanced sweet corn has better shelf life and increased sweetness while maintaining its creamy texture due to high level of water soluble polysaccharide, phytoglycogen. Super sweet corn as the name implies has higher level of sweetness and better shelf life than sugary enhanced sweet corn due to "shrunken2 (sh2)" gene although there's no creamy texture of su-based sweet corns. Distinction between sh2/sh2 and su/su genotypes in seeds is phenotypically possible. The Involvement of se/se genotype under su/su genotype, however, is visually impossible. The genotype sh2/sh2 is also phenotypically epistatic to su/su genotype when both genotypes are present in an individual, meaning the seed shape for double recessive sh2/sh2 su/su genotype is much the same as sh2/sh2 +/+ genotype. Hence, identifying the double and triple recessive homozygous genotypes from su, se and sh2 genes involves a testcross to single recessive genotype, chemical analysis or DNA-based marker development. For these reasons, sweetcorn breeders were hastened to put them together into one cultivar. This, however, appears to be no longer the case. Sweet corn companies began to sell their sweet corn hybrids with different combinations of abovementioned three genes under a few different trademarks or genetic codes, i.g. Sweet $Breed^{TM}$, Sweet $Gene^{TM}$, Synergistic corn, Augmented Supersweet corn. A total of 49 commercial sweet corn F1 hybrids with B73 as a check were genotyped using DNA-based markers. The genotype of field corn inbred B73 was +/+ +/+ +/+ for su, se and sh2 as expected. All twelve sugary enhanced sweet corn hybrids had the genotype of su/su se/se +/+. Of sixteen synergistic hybrids, thirteen cultivars had su/su se/se sh2/+ genotype while the genotype of two hybrids and the remaining one hybrid was su/su se/+ sh2/+, and su/su +/+ sh2/+, respectively. The synergistic hybrids all were recessive homozygous for su gene and heterozygous for sh2 gene. Among the fifteen augmented supersweet hybrids, only one hybrid was triple recessive homozygous (su/su se/se sh2/sh2). All the other hybrids had su/su se/+ sh2/sh2 for one hybrid, su/su +/+ sh2/sh2 for three hybrids, su/+ se/se sh2/sh2 for three hybrids, su/+ se/+ sh2/sh2 for four hybrids, and su/+ +/+ sh2/sh2 for three hybrids, respectively. What was believed to be a classic super sweet corn hybrids also had various genotypic combination. There were only two hybrids that turned out to be single recessive sh2 homozygous (+/+ +/+ sh2/sh2) while all the other five hybrids could be classified as one of augmented supersweet genotypes. Implication of the results for extension service and sweet corn breeding will be discussed.

• Korean Journal of Agricultural Science
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• v.23 no.2
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• pp.323-329
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• 1996

This paper is aims at studying the economics of scale of sweet potato cultivation. Sweet potato is one of the decreasing crop. Its cultivated areas has been decreasing more rapidly than soybean or corn. In this paper 23 farmers were surveyed, including 8 families with less than 1 ha, 7 families with 1-5 ha, and 8 families with more than 5 ha. The results are as follows; First, sweet potato cultivation is good for specialization, considering the high income per acre. Second, there is no good evidence explaining for the economy of scale of sweet potato cultivation, but there is an evidence for the profit of specialization. Large scale farmers have more incomes per acre, lather than more production or less management costs, by means of good sales methods. Third, mechanization of sweet potato cultivation is one of the key factor for successful large scale sweet potato cultivations.

• The Plant Pathology Journal
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• v.22 no.3
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• pp.239-247
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• 2006

In 2003, a survey of sweet potato virus disease was carried out in seed boxes as well as in various sweet potato fields. Virus infection rate was $5\sim100%$ and 100% at seed boxes and fields, respectively. No relationship of the disease incidence and severity was observed between sweet potato cultivating areas and cultivars. A total of 179 samples were collected and analyzed based on serological, electron microscopic and molecular properties. Field-grown sweet potatoes were examined to inspect 8 different viruses using NCM-ELISA, resulting that 30% of sweet potato was infected by one virus, whereas 70% was by more than 2 viruses. However, RT-PCR using primers selected for seven viruses, such as Sweet potato feathery mottle virus (SPFMV) revealed that of one-hundred seventy-nine tested; 71 of SPFMV, 29 of SPGV, 19 of SPFMV+SPGV, 1 of SPFMV+SwPLV, 1 of SPFMV+SPLCV, 2 of SPFMV+SPGV+SwPLV, 6 of SPFMV+SPGV+SPLCV, 2 of SPFMV+SPGV+SwPLV+SPLCV and 48 of unknown viruses were identified from the field samples. In root, viral diseases were severer in Yeoju than in Mokpo Experiment Station and infection rate was much different depending on sweet potato cultivars.

• The Plant Pathology Journal
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• v.18 no.1
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• pp.12-17
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• 2002

For the molecular detection of Sweet potaio feathery mottle virus (SPFMV) from diseased sweet potato plants, reverse transcription and polymerase chain reaction (RT-PCR) was performed with the use of a set of virus-specific primers to amplify an 816 bp product. The viral coat protein gene was selected for the design of the primers. No PCR product was amplified when Turnip mosaic virus, Potato vims Y or Cucumber mosaic virus were used as template in RT-PCR with the SPFMV-specific primers. The lowest concentration of template viral RNA required for detection was 10 fg. The vim was rapidly detected from total nucleic acids of leaves and roots from the virus-infected sweet potato plants as well as from the purified viral RNA by the RT-PCR. Twenty-four sweet potato samples were selected and analyzed by RT-PCR and restriction fragment length polymorphism (RFLP). RFLP analysis of the PCR products showed three restriction patterns, which resulted in some point mutations suggesting the existence of quasi-species for the vims in the infected sweet potato plants.

• Korean journal of food and cookery science
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• v.29 no.3
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• pp.275-281
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• 2013

This study was performed to evaluate the quality characteristics and antioxidative activities of cookies prepared with different amounts of purple sweet potato powder. Moisture and crude ash contents were lowest in the control group followed in order by the 10%, 20%, and 30% purple sweet potato powder addition groups. The lightness and yellowness values measured by Hunter color system decreased based on the amount of purple sweet potato powder concentration added to cookies. The total phenolic compound and anthocyanin contents were the highest in 30% purple sweet potato powder added cookies. The DPPH radical scavenging activity of 30% purple sweet potato powder added cookies showed the highest values among groups. In the sensory evaluation, the scores for taste, texture and overall preference were significantly highest in cookies with 10% and 20% purple sweet potato powder. Considering the scores of antioxidant activity and sensory evaluation, the concentration of between 10% and 20% addition of purple sweet potato powder would be ideal for development of functional cookies.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.5
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• pp.381-388
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• 2004

In Korea, production of super sweet corn has been economically feasible and is substituting for traditional sweet corn due to better flavor in recent years. Major limiting factors for super sweet corn production are low field emergence and low seedling vigor. The optimum water potential (WP) for the priming of normal and aged seeds of dent, sweet (su) and super sweet (sh2) corns was studied to improve low seed quality. Seeds were primed at 0, -0.3, -0.6, -0.9, and -1.2 MPa of polyethylene glycol (PEG) 8000 solution at $15^{\circ}C$ for 2 days. Priming effects differed depending on the type of corn, seed quality, and WP of PEG solution. Although WP of priming solution did not influence the emergence rate of extremely high quality normal dent corn seeds, it reduced time to $50\%$ emergence (T50) and increased plumule weight. In contrast, the emergence rate of aged field corn was improved by seed priming at 0 MPa and plumule weight and $\alpha-amylase$ activity was enhanced. The optimum WP for both normal and aged sweet and super sweet corn seeds was between -0.3 and -0.6 Mpa. At the optimum WP emergence rate, $\alpha-amylase$ activity, and content of DNA and soluble protein increased, while T50 and leakage of total sugars and electrolytes reduced.

• Korean Journal of Food Science and Technology
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• v.31 no.4
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• pp.1090-1095
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• 1999

Antioxidative and antimicrobial activities of ethanol extracts from 2 colored sweet potatoes such as purple and yellow, 5 pale yellow sweet potatoes, and 8 general cultivars of sweet potato were investigated. Colored sweet potatoes showed the highest antioxidative activity, followed by Saengmi and Yeonmi, which were pale yellow sweet potato cultivars, and Hwangmi, which was a general cultivar of sweet potato. Colored sweet potatoes also showed distinctively lower mold and surface microbial number (cfu) than the pale yellow sweet potatoes and the general cultivars of sweet potato. Although all sweet potatoes tested did not represent any antimicrobial activity against yeast and mold, they exhibited strong antimicrobial activity against Streptococcus faecalis. Especially, purple and yellow sweet potatoes showed antimicrobial activity against wide range of bacteria.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.6
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• pp.943-947
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• 1995

The sweet potato drinks were prepared with the reaction of sweet potato and complex enzyme(${\beta}-amylase,\;{\alpha}-amylase$, protease). The reducing sugar and soluble solid of sweet potato drinks were the highest on reaction of sweet potato : water(1 : 1) and complex enzyme(pH 4.5). In the color of the sweet potato drinks, hunter value(L, a, b) were the lowest on reaciton of sweet potato : water(1 : 1) and complex enzyme, and were the highest on reaciton of sweet potato : water(1 : 3) and complex enzyme(pH 4.5). In the sensory test of the sweet potato drinks, the sensory score(color, taste, flavor, texture) were the best on reaction of sweet potato : water(1 : 1) and complex enzyme(pH 4.5). These results demonstrated that the sweet potato drink was good to drink when sweet potato : water(1 : 1) were treated with complex enzyme at pH 4.5, $60^{\circ}C$ for 5 hrs.