• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.525-529
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• 2013

Contents of the total polyphenols and flavonoids in the dietary fiber from tubers and stalks of domestic sweet potatoes were investigated. In addition, their antioxidant activity as well as the potent anti-cancer effects through the growth inhibition in human colon cancer cells (HT-29) in vitro were tested. The total flavonoids as naringin equivalents in dietary fiber from tubers and stalks of sweet potatoes were $0.5{\pm}0.001$ naringin/g extract and $2.0{\pm}0.008$ mg naringin/g extract dry basis, respectively. The amounts of the total polyphenols as gallic acid equivalents were $2.8{\pm}0.01$ mg gallic acid/g dry basis and $6.3{\pm}0.03$ mg gallic acid/g dry basis, respectively. 1,2-Diphenyi-1-picrylhydrazyl (DPPH) radical-scavenging activity of the dietary fiber from stalks was 2.4 times higher than that of the dietary fiber from tubers. Interestingly, a strong growth inhibition on HT-29 cells was observed in both dietary fibers originated from stalks and tubers of sweet potato in a dose-dependent manner. In addition, we found that the dietary fiber from tubers and stalks of sweet potato increased the gene expression of tumor suppressor p53. The great potential value in the prevention of various diseases including cancer the potential value could be confirmed through effects of the dietary fiber from tubers and stalks of sweet potato on antioxidant activity and anticancer in human colon cancer.

• 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.

• Journal of Plant Biotechnology
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• v.45 no.4
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• pp.364-368
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• 2018

The R2R3-type protein IbMYB1 transcription factor is a key regulator for anthocyanin biosynthesis in the storage roots of sweet potatoes. It was previously demonstrated that the IbMYB1 expression stimulates anthocyanin pigmentation in tobacco leaves, arabidopsis and storage roots of sweet potatoes. In this study, we generated the transgenic potato plants that express the IbMYB1 genes, which accumulated high levels of anthocyanins under the control of either the tuber-specific patatin (PAT) promoter or oxidative stress-inducible peroxidase anionic 2 (SWPA2) promoter. The PAT-MYB1 transgenic lines exhibited higher anthocyanin levels in the tuber than the empty vector control (EV) or SWPA2-MYB1 plants. When combined, our results indicated that overexpression of the IbMYB1 is a highly promising strategy for the generation of transgenic plants with enhanced tissue specific anthocyanin production.

• Journal of the Korean Society of Food Science and Nutrition
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• v.27 no.5
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• pp.801-807
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• 1998

Taurine content in Korean foods of plant origin was determined for 118 commonly used food items including cereals, potatoes, pulses, nuts, seeds, vegetables and fruits. Taurine concentration in food sample was analyzed using an automated amino acid analyzer(Biochrom 20, Pharmacia LKB) based on ion-exchange chromatography. Taurine was frequently detected in plant kingdom in much lower concentrations(1/100~1/1000) than those found in marine lifes and mammals. Glutinous rice, glutinous millent and sorghum did not contain taurine, while 0.7~3.9mg taurine/100g dry wt were detected in rice, barley and their products. Potatoes and sweet potatoes contained 0.3~1.2mg taurine/100g wet wt, and seasame seeds, perilla seeds, almonds, walnuts and gigko nuts contained 0.7~3.0mg taurine/100g wt. Taurine concentration was undetectable in most of the pulses, and in a large number of vegetables. Garlic bulbs, eggplants, green peppers, lotus roots, and cabbages have a relatively high level of taurine(around 1mg taurine/100g wet wt) among vegetables. Taurine was absent or found in very low levels(<1mg taurine/100g wet wt) in most of the commonly used fruits.

• Food Science and Preservation
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• v.8 no.1
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• pp.102-108
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• 2001

Flow properties of the concentrated pigment solutions extracted from purple-fleshed sweet potatoes were determined using a cone and plate rotational viscometer for soluble solids concentration range of 25 to 65% at temperature range of 20 to 60 $^{\circ}C$. The purple-fleshed sweet potato pigment solutions exhibited Newtonian behavior. Temperature dependency for the viscosity of the solution followed the Arhenius relationship with activation energy values between 14.23 and 43.00 kJ/mol, which increased linearly with soluble solids concentration. A relationship between viscosity, temperature and soluble solids concentration was investigated. At the same temperature, the viscosity of the concentrated pigment solutions increased exponentially as the concentration increased with higher degree of such phenomena at lower temperatures.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.6
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• pp.955-961
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• 2014

This study was carried out to investigate the amounts of vitamin C in 22 sweet potato cultivars cultivated in Korea as well as evaluate the effects of cooking methods on vitamin C contents. Methods for determining vitamin C was validated by determining linearity, specificity, limit of detection (LOD), limit of quantification (LOQ), precision, and accuracy using HPLC. Results showed high linearity in the calibration curve with a coefficient of correlation ($R^2$) of 0.9999. The LOD and LOQ values for ascorbic acid (AA) were 0.03 and $0.10{\mu}g/mL$, respectively. The relative standard deviations (RSDs) for intra- and inter-day precision of AA were less than 5%. The recovery rates of AA and dehydroascorbic acid (DHA) were in the range from 98.21~98.64 and 98.28~100.68%, respectively. Depending on cultivar, contents of AA, DHA, and total ascorbic acid (TA) in sweet potatoes varied in the range from 37.76 (Sinyulmi)~89.25 (Juhwangmin), 23.37 (Sinjami)~63.94 (Sinyulmi), and 68.52 (Sinjami)~115.95 (Juhwangmin) mg/100 g, respectively, and their average levels were $56.98{\pm}12.53$, $36.46{\pm}9.03$, and $93.44{\pm}12.00mg/100g$, respectively. The average TA levels were also dependent on flesh color, whish was significantly higher in general sweet potato and orange sweet potato than in purple sweet potato. Steaming, baking, and frying processes significantly reduced AA (10.61~58.41%), DHA (2.57~52.81%), and TA (14.54~49.92%) contents in sweet potatoes. The highest reduction of AA, DHA, and TA contents was observed after baking, followed by steaming and frying. We expect that the basic information provided by this study will be useful to plant breeders and food scientists.

• Korean journal of food and cookery science
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• v.24 no.4
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• pp.501-510
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• 2008

In this study, we evaluated the quality characteristics of sweet potato Sulgidduk produced with varying amounts of fresh sweet potato, after three days of storage. The more fresh sweet potato was added, the higher were the levels of crude protein and crude lipid; however, crude ash contents were lowest in the control sample, and no significant differences in this value were detected among the samples to which fresh sweet potatoes were added. Moisture contents evidenced a tendency to decrease with increases in the amount of added fresh sweet potato and increased storage time, but pH rose with increases in the amount of added sweet potato. Total cell counts showed a tendency toward decrease with increases in the amount of added fresh sweet potato. L values tended to be low with increases in the amount of added fresh sweet potato and a values were lowest immediately after its production, although no consistent tendencies were noted in correlation with the amount of added fresh sweet potato. b values tended to increase directly with the amount of added sweet potato . With increasing storage time, the L and a values decreased, whereas the b value tended to increase. Upon textural assessment, it was observed that hardness, adhesiveness, springiness, gumminess, and chewiness(all textural components except for cohesiveness) increased with increasing quantities of added fresh sweet potato, and these factors also tended to increase with the progression of storage time. After observation via scanning electron microscopy(SEM), it was noted that the cohesiveness also increased with increasing amounts of added sweet potato. With regard to the sensory evaluation, the samples to which 15% fresh sweet potato had been added evidenced the highest acceptability in terms of color, flavor, and s0weetness, and softness and moistness in these samples decreased with increasing percentages of added sweet potato. It has been previously demonstrated that the addition of 15% fresh sweet potato resulted in optimal overall acceptability. In accordance with the aforementioned results, it has been verified that the use of fresh sweet potato in Sulgidduk is possible and probably desirable, and an addition of 15% sweet potato appears to be the optimal approach in terms of overall quality and functionality.

• The Korean Journal of Food And Nutrition
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• v.32 no.5
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• pp.494-503
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• 2019

The purpose of this study was to investigate the quality and antioxidant properties of three fermented sweet potato cultivars (Shinyulmi, Hogammi, and Shinjami) using lactic acid bacteria. During the fermentation, the pH was lowered and the titratable acidity increased. The viable cell counts of lactic acid bacteria increased 8.44-9.62 log CFU/g. Organic acid content (especially lactic acid) of sweet potatoes increased by fermentation. Also, ${\gamma}$-Aminobutyric acid increased more than 8.6 times by fermentation in all samples. The total polyphenol and flavonoid contents of sweet potato, showed insignificant changes in all samples by fermentation. ABTS radical scavenging activity of all samples slightly decreased by fermentation, but not significantly. DPPH radical scavenging activity decreased slightly by fermentation except Shinyulmi. However, when compared with the varieties, Shinjami showed the highest activity. The reducing power of Shinjami decreased slightly by fermentation, but activity was the highest among all samples. Based on these results, most of the chemical properties and functionality of fermented sweet potato are retained after fermentation, although some antioxidant activity decreases. We suggest that three fermented sweet potato cultivars (Shinyulmi, Hogammi, and Shinjami) using lactic acid bacteria can be used in various applications because of their effective functional properties.

• Applied Biological Chemistry
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• v.5
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• pp.33-38
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• 1964

As a part of the survey on the chemical compositions of Korean Sweet potatoes, the changes of chemical compositions of Suwon No. 118 and Suwon No. 147, which are representative varieties of sweet potatoes in Korea, were studied during storage. The result of the study showed the followings. 1. The moisture content of the both varieties were fairy uniform with higher value of Suwon No. 147 than another. 2. The starch content and crude starch yield in the stored root tuber were shown to be considerable uniform except decrease at the earlier part of storage and in January. 3. Reducing sugar content of them showed increase at earlier part, then almost uniform except gradual decrease in later part of the storage. 4. The content of total soluble sugar were gradually increased at the earlier part, then became almost uniform at the later part of the storage. 5. The sucrose content showed gradual increase except at the earlier part of the storage in which both varieties showed different feature in decrease of the content. 6. The content of crude protein and soluble protein were almost uniform throughout the storage.

• 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.