• Korean journal of food and cookery science
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• v.32 no.4
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• pp.524-530
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• 2016

Purpose: The properties of starch and starch gel prepared from a newly inbred sweet potato, Daeyumi were compared to the properties of starch and starch gel prepared from Sinyulmi which is a well known mealy type sweet potato. Methods: The starch was isolated by using the alkaline steeping method. Physicochemical, pasting, and thermal properties, and crystallinity were measured. The texture properties of starch gel (10%, w/w) were examined. Results: The amylose contents of Daeyumi and Sinyulmi starches were 25.57% and 22.59%, respectively. The initial pasting temperature of Daeyumi starch was significantly higher than that of Sinyulmi starch (p<0.05), but other paste viscosities were not different. The peak and conclusion temperatures of Daeyumi starch were higher than those of Sinyulmi starch by differential scanning calorimetry. The shape of Daeyumi starch gel was more clear and rigid than the shape of Sinyulmi starch gel. The surface and the upper side of Daeyumi starch gel were smoother than the surface and the upper side of Sinyulmi starch gel. Hardness and gumminess were higher in Daeyumi starch gel than in Sinyulmi starch gel. The crystallinity types of Daeyumi and Sinyulmi starches were $C_b$ and A types, respectively, but starch gels showed an amorphous type. Conclusion: Therefore, it is suggested that Daeyumi starch would have better physicochemical properties and higher quality of starch gel than Sinyulmi starch.

• Korean Journal of Food Science and Technology
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• v.17 no.6
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• pp.421-425
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• 1985

The changes of pectic substances during baking at $175{\sim}180^{\circ}C$ for 30 minutes and polygalacturonase activities of three sweet potato cultivars on textural properties were investigated. The three different types of sweet potato cultivars were the dry type (Wonki), the intermediate type (Shinmi), and the moist type (Chunmi). The moisture content, alcohol insoluble solid content, composition of pectic substances and hardness were determined before and after baking. It was found that HCl-soluble pectin was significantly changed into water soluble and sodium hexametaphosphate soluble pectin by baking. The dry type, Wonki showed the lowest moisture content, but the highest alcohol insoluble solid content and hardness. Wonki, whose polygalacturonase activity was the highest, had the highest HCl-soluble pectin content after backing.

• Food Science and Biotechnology
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• v.18 no.6
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• pp.1487-1494
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• 2009

The effects of drying temperature (55, 60, and $65^{\circ}C$) and addition levels of maltodextrin (MD) (10, 20, and 30%) on the physicochemical properties and nutritional quality of purple sweet potato flour were investigated. MD-added flours had higher $L^*$ values, water soluble index, total phenolic, and anthocyanin contents than untreated flour. However, $a^*$, $b^*$ values, water absorption index, and swelling capacity were dependent on the drying temperature and MD concentration. On the other hand, untreated flour had a higher ascorbic acid content compared to the MD-treated flour. Ascorbic acid contents decreased, whereas anthocyanin content was not significantly different, with increasing drying temperatures. MD was positively correlated with phenolic content, anthocyanin, hue angle, and water soluble index. However, there was no correlation between quality parameters and glass transition temperature. The best quality product was obtained when samples were pretreated with MD before drying, regardless of drying temperature.

• Korean journal of food and cookery science
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• v.24 no.4
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• pp.511-516
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• 2008

In this study, composite flour and dough were prepared with concentrated sweet pumpkin powder(CSPP) at varying concentrations of 3, 6, 9, 12, and 15%. The samples and a control were then compared with regards to quality characteristics, including moisture, protein, and ash contents, farinogram characteristics, amylogram characteristics, and falling number of flour and extensogram characteristics of dough, in an effort to determine the optimal ratio of CSPP in the formulation. As the CSPP content increased, the moisture and protein contents of the flour increased, whereas the ash contents decreased. With regard to the farinogram characteristics of flour, water absorption, development time, and stability decreased with increasing CSPP content, while weakness increased. The control group evidenced a significantly higher beginning temperature of gelatinization as compared to the CSPP samples. The temperature of maximum viscosity, maximum viscosity, and falling number of flour decreased with increasing CSPP content. With regard to the extensogram characteristics of dough, extensibility decreased with increasing testing time and CSPP content, whereas resistance, maximum resistance, and R/E ratio increased. In conclusion, these results show that $6{\sim}9%$ CSPP may prove very useful as a substitute for wheat flour in the production of hardroll bread, and may provide good nutritional and functional properties.

• 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 Food Science and Technology
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• v.32 no.4
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• pp.834-842
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• 2000

In order to investigate the characteristics of various sweet potato starches, gelatinization temperatures, solution viscosity of starch separated from two cultivars of the dry type sweet potatoes(Yulmi and Gunmi), one cultivar of moist type sweet potato(Jinmi), and one cultivar of purple colored variety(Jami) were compared, and properties of the edible films prepared with the starches were determined. Under a differential scanning colorimetry(DSC), initial temperatures for starch gelatinization of the dry type sweet potatoes (Yulmi and Gunmi) were higher than that of the moist type sweet potato (Jinmi), and that of Jami was close to those of the dry type ones. The sweet potato starch solutions tested by a cone and plate viscometer, showed peudoplastic characteristics. The moist type sweet potato was the most viscous followed by Jami, Yulmi, and Gunmi among the tested starch solutions. Total color difference of the edible films prepared with different cultivars of sweet potatoes showed appreciable differences between cultivars, caused by differences in Hunterb values. Water Vapor Permeability (WVP) of sweet potato starch films also showed significant differences between cultivars. Films prepared with the dry type sweet potato, Gunmi, showed the lowest WVP value of $0.83{\times}10^{-9}\;g\;{\cdot}\;m/m^{2}\;{\cdot}\;s\;{\cdot}\;Pa$, followed by Jami, Yulmi, and Jinmi. Water solubility of the films did not show any significant differences between cultivars. Tensile strength of the dry type sweet potato and Jami, which ranged 14.18-18.75 MPa, were higher than that of the moist type sweet potato, which was 4.66 MPa. Elongation values of the films, which were 5-6%, indicated that sweet potato starch films were not so elastic.

• Food Science and Preservation
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• v.14 no.1
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• pp.8-17
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• 2007

The efficacy of strong acidic electrolyzed water (SAEW) at pH 2.53, with ORP of 1,088 mV and HClO concentration of 91.25 ppm, and low alkaline electrolyzed water (LAEW) at pH 8.756, with ORP of 534 mV and HClO concentration of 105.70 ppm, as storing liquids for peeled potato and sweet potato was evaluated in this study. During storage at $5^{\circ}C$, total phenolic contents and PPO activities of peeled potato and sweet potato stored in SAEW and LAEW were lower than those of control samples stored in tap racer (TW) with 0.85% (w/v) NaCl and 0.5% (w/v) sodium metabisulfite (SMS). Increment in color differences and decreases in hardness of peeled potato and sweet potato stored in SAEW and LAEW were lower than those of controls. Also, SAEW and LAEW inhibited growth of microorganisms for at least 3-6 days of storage. The sensory characteristics of peeled potato and sweet potato stored in LAEW were best during the first half of the storage period, compared to samples preserved by other methods.

• Korean Journal of Food Science and Technology
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• v.45 no.3
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• pp.305-311
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• 2013

Effects of cultivation methods on quality characteristics, pasting characteristics, chemical components, and antioxidant activities of sweet potatoes (Ipomoea batatas (L.) Lam) were determined. The Brix degree, hunter color value, pasting characteristics, moisture, protein, and mineral contents of the sweet potatoes showed significant differences from cultivation methods. The total polyphenol and flavonoid contents of the methanolic extracts of the sweet potato's pericarp were higher than sweet potato's sarcocarp. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of the sweet potato's pericarp on the conventional culture and successful cropped hairy vetch culture was 776.38 and 715.20 mg TE/100 g sample. The 2,2'-azino-bis-3-ethylbenzo-thiazoline-6-sulfonic acid (ABTS) radical scavenging activity of the sweet potato's pericarp on the conventional culture and successful cropped hairy vetch culture was 708.03 and 708.58 mg TE/100 g sample. Generally, there was a difference in antioxidant compound content and radical scavenging activity on the methanolic extract of sweet potato with cultivation methods.

• The Korean Journal of Food And Nutrition
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• v.27 no.6
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• pp.1090-1095
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• 2014

Anthocyanins, a class of flavonoids, are natural water-soluble pigments, which are mainly found in vegetables and fruits. Anthocyanins have attractive pharmacological activities, such as anti-oxidant, anti-inflammatory, anti-cancer, and anti-diabetic. The purpose of this study was to investigate the protective effects of anthocyanins-rich fraction (ANF) from Korean purple sweet potato variety, "Shinjami", against hydrogen peroxide ($H_2O_2$)-induced oxidative stress. In our results, pre-treatment of HepG2 cells with ANF ($10{\mu}g/mL$) significantly prevented cell death and maintained cell integrity, following exposure to 0.9 mM hydrogen peroxide. The $H_2O_2$-dependent production of intracellular ROS was also significantly decreased by pre-treatment with ANF (6 h, $10{\mu}g/mL$). In addition, ANF increased the mRNA levels of antioxidant enzymes, catalase and glutathione level in $H_2O_2$-treated HepG2 cells. These results indicated that ANF protected HepG2 cells against $H_2O_2$-induced oxidative stress by inducing protective system.

• Journal of Food Hygiene and Safety
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• v.32 no.6
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• pp.477-484
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• 2017

This study was conducted to investigate the content of sulfur dioxide, carotenoids and the degree of contamination of Bacillus cereus in 33 kinds of dried sweet potato from domestic mainly dried agricultural products in Korea. According to the characteristics of dried sweet potato samples, it was classified into four clusters and as a result of analyzing the contents of sulfur dioxide, carotenoids and the degree of contamination B. cereus was no significant difference among the clusters. The detection ranges of residual sulfur dioxide from 33 dried sweet potatoes ranged from 0.38 to 28.16 mg/kg, three cases (9.09%) were detected at the reference level of 10 mg/kg or more. But no samples exceeding 30 mg/kg, the tolerance level of sulfur dioxide in dried sweet potatoes were detected. Since dried sweet potato does not have a standard for carotenoids, when comparing the national and international standards of carotenoids, the range of detection of carotenoids in dried sweet potato was $46{\sim}2,663{\mu}g$/100 g, which was within the reference range of $0{\sim}9,826{\mu}g$/100 g. In principle colonies suspected to be B. cereus in dried sweet potato were not detected. In 7 cases (21.21%), there were detected in the range of 0.05~1.59 log CFU/g but not more than 3 log CFU/g as the reference value. The results of this study are expected to be used as basic data to establish quality standard for dried sweet potatoes. In order to control the quality of dried sweet potatoes in domestic market, raw materials, drying method and packaging after distribution, it is necessary to maintain and maintain the process steadily.