• Food Science and Preservation
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• v.7 no.3
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• pp.331-336
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• 2000

The phenolic compounds of Korean sweet potatoes, Mokpo 18 and Yulmi, were extracted by using 70%-methanol and the extracts(ME) were fractionated and obtained three fractions such as free phenolic acid(FPAF), soluble phenolic acid ester(SPAF) and insoluble bound phenolic acid(BPAF) fractions. The antioxidative activities(AA) was represented as the peroxide values(POVs). The POVs were calculated by measuring the oxidation of linoleic acid and lard emulsions at $60^{\circ}C$. AA of FPAF has shown the most effective. AA of FPAF were more effective than those of ME in both Yulmi and Mokpo 18. AA of the ME of Mokpo 18 were more effective than those of Yulmi, however, those of FPAF in Ulmi were more effective than in Mokpo 18. The POVs of ME and FPAF of the peel part in both sweet potatoes were more effective than those of peeled part. The qualitative and quantitative analysis of the phenolic compounds in both sweet-potatoes were performed by using high performance liquid chromatography(HPLC) and the major phenolic compounds were identified as chlorogenic acid and caffeic acid. The contents of caffeic acid were 0.684mg/g in the peel part and 0.028mg/g in the peeled part of Yulmi and 0.472mg/g in the peel part and 0.046mg/g in the peeled part of Mokpo 18 and those of chlorogenic acid was 0.674mg/g, 0.926mg/g, and 0.012mg/g, respectively. In comparative test of antioxidative activities between a standard chlorogenic acid and caffeic acid, AA of caffeic acid were more effective than those of chlorogenic acid.

• 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.

• Korean Journal of Food Science and Technology
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• v.40 no.2
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• pp.184-189
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• 2008

Effects of sucrose at different concentrations (0, 10, 20, and 30%, w/w) on steady and dynamic shear rheological properties of sweet potato starch (SPS) paste (5%, w/w) were investigated. The steady shear rheological properties of SPS-sucrose composites were determined from rheological parameters based on power law and Casson flow models. At 25$^{\circ}C$ all the samples showed pseudoplastic and thixoropic behavior with high yield stress. Consistence index (K), apparent viscosity (${\eta}_{a,100}$), and yield stress (${\sigma}_{oc}$) values of SPS-sucrose composites decreased with increasing sucrose concentration from 10% to 30%. The decrease of swelling power was observed at higher sucrose concentration (>20%) and the low swelling power yielded a lower K, ${\eta}_{a,100}$, and ${\sigma}_{oc}$ values. In temperature range of 25-70$^{\circ}C$, Arrhenius equation adequately assessed variation with temperature. Oscillatory test data showed weak gel-like behavior. Magnitudes of storage (G') and loss (G") moduli increased with an increase in sucrose concentration and frequency. The SPS-sucrose composite at 30% concentration closely followed the Cox-Merz superposition rule.

• Korean Journal of Food Science and Technology
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• v.10 no.3
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• pp.331-336
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• 1978

In an attempt to study the possibility of substituting sweet potato for cereals as raw materials for Kochujang, three kinds of Kochujang were made from barley, sweet potato or 50% barley and 50% sweet potato, The results of component variation during the ripening and the effect of temperature on the aging in the harvesting season of sweet potato were as follows: 1) Kochujang is, usually, manufactured in May, but no difference was observed in aging condition when it was manufactured in September, the season of sweet potato harvest, since the inner temperature of the product was around $20^{\circ}C$. 2) The total reducing sugar content and maturity reached maximum after $40{\sim}50\;days$ of fermentation in the three treatments and crude fat content tended to be slightly decreased during fermentation. 3) Lightness in color of the three kinds of Kochujang decreased by exposure to sunlight. Sweetpotato Kochujang showed a stronger tendency to increase the redness as compared with the rest. 4) Sensory evaluation showed that sweet potato Kochujang was less acceptable than barley Kochujang due to disagreeable flavor of sweet potato but mixed Kochujang showed little difference, as compared with barley Kochujang.

• Food Science and Preservation
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• v.18 no.3
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• pp.414-422
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• 2011

The optimum condition for phenolics contents extraction from purple sweet potato was 12 hrs. in 50% ethanol. The electron donating scavenging activities (DPPH), ABTS radical cation decolorization (ABTS) and antioxidant protection factor (PF) of Jami, Yeonjami and Shinjami were higher than general sweet potato, and thiobarbituric acid reaction substance (TBARs) was below 30%. The minimum inhibitory concentration (MIC) against Staphylococcus aureus and Escherichia coli on skin were each 5,000 and 2,500 ppm in all purple sweet potatoes, and MIC of Jami was the lowest as 2,500 ppm against Staphlococcus epidermidis. The whitening (tyrosinase inhibitory) activity of purple sweet potatoes was the highest as 62.5% and 48.7% in Jami water and ethanol extracts. The anti-inflammation (hyaluronidase inhibitory) activity of purple sweet potatoes was the highest as 25.3% and 94.4% in Jami water and ethanol extracts. The safety of cosmetic with Jam; extracts was assessed by various safety profiles. pH and viscosity change of essence for 90 days was not detected. Cosmetic was stable to temperature and light for 90 days. The result to measure changes of skin color and pore size of the skin was that an aged skin was more effective than young skin.

• Food Science and Preservation
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• v.19 no.6
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• pp.833-840
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• 2012

In this study, purple sweet potato muffins were made with the addition of 0, 25, 50, 75, and 100% rice flour, and their quality characteristics were determined. The weight and height increased with the increase in the amount of rice flour added. The moisture contents decreased significantly. As the amount of rice flour added increased, the pH and acidity decreased. The lightness and yellowness of the rice flour decreased significantly, but the redness increased with increasing purple sweet potato content. The textural properties, such as the cohesiveness, chewiness, and brittleness, were significantly lower in the groups with added rice flour. The DPPH radical scavenging activity was significantly higher in the purple sweet potato muffins to which 50 and 75% rice flour were added compared to those in the control. The results of the sensory evaluation showed that there was no significant difference in flavor among the samples. The chewiness was higher with 50, 75, and 100% rice flour than with 0 and 25% rice flour. The groups with 50 and 75% rice flour had significantly higher scores for overall acceptability compared to the control group.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.46 no.3
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• pp.176-179
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• 2001

To obtain the basic information of high yielding ability for varietal improvement and cultural practice, reciprocal grafts were made analyzed among five sweet potato cultivars. Five cultivars were characterized with the different in whose source and sink capacities. Grafting decreased main vine length, number of tuberous roots per plant, but its effects were different among grafting combinations. The growth of vines was affected more by scion, while growth and yield of under-ground were influenced more by stock. Grafting effects, interactions between stock and scion for main vine length and number of tuberous roots were highly significant in diallel grafting. The percentage of marketable tuberous roots was higher in the order of stem cutting＞self grafting＞reciprocal grafting.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.4
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• pp.555-560
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• 2000

Anthocyanin pigments of purple-fleshed sweet potato (Ipomoea batatas) were extracted with methanol containing 1% HCL and purified with Amberlite IRC-50 cation exchange resin column chromatography. ndividual pigments were isolated by paper chromatography. Among the four bands obtained by paper chromatography, three major bands were identified to be pure pigments by HPLC system. Two pigments were identified through the analysis of acyl moiety, sugar moiety, alkaline degradation products of aglycone, Rf value of paper chromatogram and retention time of HPLC. The anthocyanin pigments of purple-fleshed weet potato seemed to be composed of peonidin-3-diglucoside-5-glucoside acylated with caffeic or ferulic acids.

• Korean Journal of Food Science and Technology
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• v.29 no.3
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• pp.497-501
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• 1997

Kinetic parameters on heat-induced color changes of anthocyanin pigment from purple sweet potato were determined in the temperature range of $121{\sim}141^{\circ}C$. Color change determined by a browning index $(A_{532}\;nm/A_{420}\;nm)$ followed second order reaction kinetics. Activation energy values of purple sweet potato pigment solutions of pH 2.0, 3.0, 4.0 and 5.0 were 69.57, 76.68, 81.07 and 92.98 kJ/mol, respectively, indicating that temperature dependency of the reaction increased with pH. Apparent kinetic compensation effect between preex-ponential factor and activation energy value was observed.

• The Korean Journal of Mycology
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• v.42 no.1
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• pp.91-94
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• 2014

In June 2013, surface rot symptoms were observed on sweet potatoes (Ipomoea batatas) in Yeoju city, Korea. The lesions were circular, light to dark brown, firm, dry, and superficial. The diseased area became sunken in older tissues, and the symptoms usually did not extend deeply into the flesh. Seven isolates of Fusarium species were isolated from diseased sweet potatoes. All isolates were identified as Fusarium oxysporum based on morphological characteristics on CLA medium. To confirm the identification, molecular analysis of elongation factor 1 alpha gene was conducted. Among the isolates, however, four isolates were F. commune, and three isolates were F. oxysporum based on the DNA sequence data. Pathogenicity was tested using agar block inoculation on wounded or unwounded sweet potato pieces. Lesions were observed on wounded sweet potato pieces after 7 days inoculation in only F. commune isolates. This is the first report that F. commune causes Fusarium surface rot of sweet potato in Korea.