• KOREAN JOURNAL OF CROP SCIENCE
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• v.62 no.1
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• pp.51-59
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• 2017

To obtain basic data on the effects of differences cultivation periods and methods on growth and development of sweet potato tuber. We investigated growth and development of six major cultivars showing different characteristics, such as dry type(Yulmi, YM; Jinhongmi, JHM), intermediate type(Pungwonmi, PWM; Hogammi, HGM), and purple type(Sinjami, SJM; Danjami, DJM). The average tuber weight of YM and JHM was 4.1 and 8.6 g respectively, 50 days after transplant. At 80 days, the weight of YM and JHM rapidly increased to 25.2 and 26.1 g, respectively. Finally, at 120 days, the weight of YM and JHM increased to 120.7 and 79.4 g, respectively. The average tuber weight of PWM and HGM was 13 and 3.3 g, respectively, 50 days after transplant. The development pattern of PWM showed a consistent increase in tuber weight during the cultivation period, an average weight of 104.2 g at 120 days. However, the tuber development pattern of HGM was different from that of PWM. The average tuber weight of HGM rapidly increased for 100 days after transplant and then showed no increase at 120 days. In case of purple type sweet potato, the average tuber weight of SJM consistently increased during the cultivation period, whereas DJM showed rapid increase in average tuber weight at 80 days after transplant. Korean consumers prefer small, round sweet potato approximately 100g in weight. Based on the results, YM, PWM and SJM are classified as early developing cultivars that can be harvested approximately 120 days after transplant. On the other hand, JHM, HGM, and DJM are classified as late developing cultivars that can be harvested approximately 130 days after transplant.

• Journal of Applied Biological Chemistry
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• v.58 no.1
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• pp.21-24
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• 2015

Antioxidant activities of ethanol extracts from three types of sweet potatoes with distinctive flesh color (white, orange, and purple) were investigated. Total phenolic content of purple-fleshed sweet potato (PF) was always 2- to 5-fold higher than those of white-fleshed (WF) and orange-fleshed sweet potato (OF). 2,2-diphenyl-1-picryl-hydrazyl free radical scavenging activity of 70% ethanol extracts was highest ($EC_{50}$ = 0.179 mg/mL) for PF and lowest ($EC_{50}$ = 2.127 mg/mL) for OF. And then, reducing power was also highest ($EC_{50}$ = 0.236 mg/mL) for PF and lowest ($EC_{50}$ = 1.587 mg/mL) for WF. Antioxidant activities of 70% ethanol extracts were closely related to the amount of total phenolics. These results imply that antioxidant activity of PF is 6.7 to 11.9 times higher than those of WF and OF.

• Journal of Nutrition and Health
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• v.48 no.1
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• pp.1-8
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• 2015

Purpose: Anthocyanins from purple sweet potato (PSP) have been investigated in vitro and in animals and found to have a protective effect against oxidative hepatic damage. In this study, we investigated that aqueous extract of PSP can ameliorate the dysfunction of lipid metabolism in mice fed a high fat/cholesterol diet. Methods: Forty C57BL/6J mice were randomly divided into 5 groups (n = 8) and fed one of the following diets for 8 weeks; normal fat (NF) diet; high fat/cholesterol (HFC) diet; HFC with 1.25% PSP (HFPL) diet; HFC with 2.5% PSP (HFPM) diet; HFC with 5% PSP (HFPH) diet. Results: Non-alcoholic fatty liver was manifested in the HFC group by showing increased levels in plasma alanine aminotransferase (ALT) activity, total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C), increased level of TC and presence of many large lipid droplets in the liver, and increased fat cell size in the HFC group compared with the NF group. However, administration of HFC induced a significant decrease in food intake, resulting in decrease in fat mass. Co-administration of PSP did not lead to reversal of body weight changes, ALT activity, and lipid levels in plasma and the liver, but suppressed excess enlargement of the fat cell size through increasing carnitine palmitoyltransferase-1 (CPT-1) gene expression in the liver. Accordingly, the number of fat droplets in the liver was reduced in PSP administered groups. Conclusion: Taken together, these results suggest that PSP may have a protective effect on the dysfunction of lipid metabolism. Conduct of further studies on the coordinated regulation of PSP for lipid metabolic homeostasis at the liver-adipose tissue axis is needed.

• Journal of Applied Biological Chemistry
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• v.58 no.4
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• pp.311-316
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• 2015

Yogurt was prepared with different substitution ratio [10, 30, and 50% (w/w)] of skim milk with enzymatically hydrolyzed purple sweet potato powder (EHPSPP) and fermented at $40^{\circ}C$ for 15 h. Fermentation characteristics and antioxidant activities of the yogurt were evaluated in terms of acid production (pH and titratable acidity) and lactic acid bacterial counts and DPPH radical scavenging activity, respectively. After 15 h fermentation, titratable acidity of EHPSPP yogurt was 0.80-0.89% and was lower than that (0.93%) of yogurt made without EHPSPP. The acid production and the number of viable lactic acid bacterial cell decreased with increasing the substitution ratio. The sensory score of EHPSPP yogurt prepared with 30% substitution ratio showed the highest values in taste and overall acceptability among the tested yogurt preparations. DPPH radical scavenging activity increased with increasing the substitution ratio in yogurt fermented for 12 h. The total phenolic content of 30% EHPSPP yogurt was 40% higher than that of skim milk yogurt. These results suggest that EHPSPP can be used as substituent of skim milk and the optimum substitution ratio is around 30%.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.spc1
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• pp.141-146
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• 2005

The objective of this study was to determine the characterisics of quality and antioxidant with various sweet potato(SP) varieties. The differences of skin color between general and colored SP was not significant. The flesh color of steamed SP was the lower than flesh of raw SP, and especially steamed purple SP(5.24) was lower than flesh SP(22.0). In physical characteristics, the hardness of raw SP showed the low values and the springness, gumness and hardness among steamed SP varieties was not significant. The total phenol content(TPC) of purple, yellow-fleshed and general SP had 13.1, 6.22 and 3.02 mg/g, respectively. In DPPH, the purple-fleshed SP had the highest free radical scanvering. Also, shingunmi$(88.5\%)$, Saengmi$(80.9\%)$ and Shinchunmi$(78.9\%)$ show the high antioxidant activities. The redness of SP was positively correlated with TPC in raw and steamed. However, the yellowness of flesh SP was negatively correlated with DPPH.

• Korean Journal of Food Science and Technology
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• v.28 no.2
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• pp.352-359
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• 1996

Stabilities of purple sweet potato (PSP) anthocyanin pigment on pH, sugars, organic acids, metal ions, ascorbic acid and light were investigated to provide the basic information for utilization of PSP as a potential source of anthocyanin pigment. pH has a marked influences on the color of the PSP anthocyanin solution; i.e., at low pH the color of PSP was more intense and stable. It showed characteristic bathochromic shift as the pH of the solution increased. Among the sugars tested, glucose showed a protective effect on the color of PSP pigment to raise the color intensity and stability, while sucrose and fructose showed an adverse effect. Addition of organic acids greatly increased the stability of PSP anthocyanin pigment. Citric acid was found to be the most effective followed by malic. tartaric, and succinic acids. Most metal ions except $Al^{3+}$ and $Cd^{2+} were found to be detrimental effect on the stability of PSP pigment. Ascorbic acid degraded PSP pigment considerably, and had a synergistic effect with oxygen on the pigment degradation. The effect of light on PSP pigment was found to be very deleterious. The pigment degradation can be minimized by shielding the light from the pigment solution.

• Korean Journal of Food Science and Technology
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• v.44 no.6
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• pp.728-735
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• 2012

Makgeolli is the oldest Korean traditional wine made from rice, and contains 6-8% alcohol. Also, nuruk is traditionally prepared by exposing moistened ground wheat or rice to the air, and there contained airborne microorganism. In this study, purple sweet potato (PSP) was used as a raw material in the rice nuruk- and makgeolli-making processes. PSP rice nuruk (RN) was made with rice and 0-10% (w/w) PSP, and the characteristics of makgeolli were studied during fermentation. The pH during fermentation decreased from 4.27 (0% PSP-RN), 4.59 (2.5%), 4.50 (5.0%), 4.46 (7.5%), and 4.43 (10.0%) of initial fermentation day to 4.12, 3.82, 3.67, 3.71, and 3.66, respectively, at day 7. The sugar contents increased from $0.4^{\circ}Bx$ of the initial day to $8.0-8.4^{\circ}Bx$, and the levels of alcohol increased to 13.0% (0% PSP-RN), 13.2% (2.5%), 12.8% (5.0, 7.5, and 10.0%) by day 7, respectively. In addition, the contents of soluble anthocyanins and phenolics increased from 0.001-0.121 and 0.2-0.27 g/L on the initial fermentation day to 0.002-0.166 and 1.65-1.87 g/L, corresponding to increases in levels of antioxidant activities of 20-50%, respectively.

• Korean Journal of Food Science and Technology
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• v.45 no.1
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• pp.47-52
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• 2013

The feasibility of incorporating purple sweet potato concentrate (PSPC) as a value-added food ingredient in convenient food products, using a model system of jelly, was investigated. The pH and soluble solids content gradually increased with the increasing levels of PSPC added (p<0.05). The moisture content ranged from 82.03-83.82%. Lightness decreased, whereas redness and yellowness increased significantly with the higher amount of PSPC in the formulation (p<0.05). Turbidity and hardness also increased significantly (p<0.05). Total polyphenol content and DPPH radical scavenging activity increased significantly with the addition of PSPC (p<0.05). The consumer acceptance test indicated that the addition of PSPC had a favorable effect on consumer acceptances in all attributes. The jelly with 2% PSPC is recommended (with respect to the overall acceptance score) for taking advantage of the functional properties of PSPC without sacrificing consumer acceptability.

• 한국약용작물학회:학술대회논문집
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• 2009.05a
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• pp.293-294
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• 2009

• Proceedings of the Korean Nutrition Society Conference
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• 2003.05a
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• pp.125.1-125.1
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• 2003