• Korean Journal of Food Science and Technology
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• v.45 no.6
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• pp.747-753
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• 2013

The physicochemical properties of sweet potato (SP) starches reclaimed from an SP-processing sludge without freezing (RC/NF) and with freezing (RC/FR) were investigated. Lab-isolated (LI) SP starch, as a control, were prepared from raw SP. RC/NF and RC/FR SP starches were recovered from SP-processing sludges by the repeated sieving and washing procedure. The total starch contents and amylopectin branch-chain distributions did not differ for three SP starches. Relative to LI and RC/NF SP starches (possessing similar physicochemical characteristics), the apparent amylose and phosphorus contents, swelling factor, and pasting viscosity were reduced for RC/FR SP starch. However, the freezing treatment altered X-ray diffraction pattern (at $5.5^{\circ}$, $11-12^{\circ}$, and $24^{\circ}$ $2{\theta}$) of RC/FR SP starch, which likely increased its gelatinization peak and completion temperatures. Its amorphous region in total diffractogram was reduced, resulting in the enhanced relative crystallinity. Overall results suggested SP starches recovered from an SP-processing sludge would have the potential to replace commercial SP starch products.

• 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.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.10
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• pp.1476-1480
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• 2010

Physicochemical properties of flours prepared from sweet potatoes with different flesh color (white, yellow/orange and purple) were investigated. Sweet potatoes were soaked in solutions of antibrowning agents such as sodium metabisulfite and citric acid, and freeze or hot air-dried prior to grinding to produce sweet potato flours. Sweet potato flours with different flesh colors showed differences in chemical composition. Purplefleshed sweet potato flour had higher protein, ash, and dietary fiber contents that white and yellow/orangefleshed sweet potato flours. Average particle size of yellow/orange-fleshed sweet potato flour was higher than those of white/yellow or purple-fleshed sweet potato flour. Both water absorption index (WAI) and oil absorption capacity of flours prepared from sweet potatoes by hot-air drying were higher than those from sweet potatoes by freeze drying.

• The Korean Journal of Food And Nutrition
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• v.26 no.1
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• pp.29-34
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• 2013

The objective of this study was to manufacture three kinds of domestic sweet potato Makgeolli using a mixture design and an optimization technique. The effects of four different manufacture methods, such as simultaneous saccharification and fermentation (SSF) with or without malt and separate hydrolysis and fermentation (SHF) with or without malt were determined. The SSF methods of Makgeolli produced higher alcohol content than that of SHF methods. The sensory score was not influenced by different making methods. Fourteen experimental points were selected, and rice (10~50%), sweet potato (10~50%) and water (40~60%) were chosen as independent variables. The measured responses were sensory preference, total polyphenol content, and DPPH radical scavenging activities. The ratio of the optimum sweet potato Makgeolli mixture formulation was developed as 15.11 (rice): 44.89 (sweet potato): 40 (water) using the optimization technique. The desirability of the optimum mixture formulation was 0.839. Yellow sweet potato Makgeolli using the optimum mixture formulation produced higher soluble sugar content compared to others. Regular sweet potato Makgeolli produced higher pH. The purple sweet potato Makgeolli's total polyphenol content and DPPH radical scavenging activity were measured to be the highest at $771.91{\pm}1.42mg\;GAE/{\ell}$, $131.55{\pm}4.03%$.

• 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.

• 농업기술회보
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• v.46 no.1
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• pp.34-35
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• 2009

최근 소비자들은 먹을거리의 안전성, 건강 다이어트식품으로 겨울철 간식용뿐만 아니라 맛탕, 고구마밥, 튀김 등 요리에도 이용되고 있는 고구마를 선호한다. 그러나 고구마는 수분이 많고 저온에 노출되면 냉해를 받아 부패하게 되므로 저장관리가 까다롭다. 수확 후 저장관리를 잘한다면 수확 직후부터 이듬해 7월 중 하순, 햇고구마가 출하될 때까지 연중 공급이 가능하다.

• Food Science and Preservation
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• v.23 no.4
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• pp.538-546
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• 2016

Kochujang was prepared by replacement of rice (25%, control) with pumpkin or purple sweet potato by 0. 5, 10, and 15% (total addition ratio of rice and sweet potato=25% of sample). Effects of the addition of sweet potato on physiochemical properties of fermented Kochujang were investigated. Viable cells of yeast decreased in the sweet potato-added Kochujang at the later stage of fermentation, while there was no significant difference in the number of bacteria among the test groups. As the addition ratio sweet potato increased, ${\alpha}$-amylase activity increased while protease activity decreased. Hunter L, a, and b values of Kochujang prepared with purple sweet potato were lower than those with pumpkin sweet potato. Changes in ${\Delta}E$ value was greater in Kochujang prepared with pumpkin sweet potato than that with purple sweet potato. Oxidation-reduction potential and water activity were higher in sweet potato-Kochujang than control, but reducing sugar content was higher in control. Alcohol and amino-type nitrogen contents were higher in Kochujang prepared with pumpkin sweet potato than that with purple sweet potato, but it was not significant. Overall sensory acceptability was highest in Kochujang prepared with 10% of purple sweet potato while that with 15% pumpkin sweet potato was the least preferred.

• Korean Journal of Agricultural Science
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• v.11 no.1
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• pp.114-119
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• 1984

In order to improve the quality of silages made of rice straw, clover and sweet potato stalk, crushed fresh sweet potatoes(CFSP) were added at various levels to each silage. When the fermentation was completed, the chemical composition, pH and main organic acid contents of each silage were analized. The results obtained were summarized. 1. The moisture content of sweet potato stalk silage was highest among all silages tested. The clover silage showed the highest value in crude protein content. On the other hand, the rice straw silages were high in NFE and crude fiber contents. When the level of CFSP increased, the NFE contents tended to increase and crude fiber decrease. 2. The content of total organic was highest in clover silage. However, the percentage of lactic acid in total acid content was highest in sweet potato silage. The percentage of lactic ac id in total acid content was increased in paralled with the levels of CFSP. 3. The sweet potato stalk silages showed the lowest pH value (4.10-4.20). The highest pH values were 4.75-5.22 in rice straw silage. The addition of CFSP tended to lower the pH. 4. It appears the quality of clover and rice straw silages can be imp roved by adding CFSP at 5 and 10% levels, respectively, on fresh weight basis. The addition of CFSP to the sweet potato stalk silage, however, was not effective in this experiment.

• Korean Journal of Food Science and Technology
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• v.9 no.3
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• pp.220-224
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• 1977

To dry the sweet potato efficiently, the fresh sweet potato was soaked in hot water of $60{\sim}65^{\circ}C$ for $1{\sim}1.5hrs.$ and cut into 0.5cm thick slices, followed by pressing at $40kg/cm^2$. This predehydrated cake contained $43{\sim}55%$ moisture and can be dried further either by sundrying or hot air drying. Using the dried sweet potato, ethanol was produced (ethanol production; 433l/M/T) by the conventional alcohol fermentation. The extracts as a by-product ($340{\sim}450ml$ per Kg of fresh potato) contained 5% total sugar and may be used directly for alcohol fermentation without further concentration.

• Korean Journal of Food Science and Technology
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• v.46 no.2
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• pp.224-230
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• 2014

The characteristics and antioxidative activities of yellow and black soybean cheonggukjang prepared with the addition of purple sweet potato (Ipomoea batatas cv. Jami) were evaluated. In sensory evaluation experiments involving the addition of purple sweet potatoes to cheonggukjang at 0, 5, 10, 20, and 30% ratios (w/w), yellow (YCAP) and black (BCAP) soybean cheonggukjang with 20% purple sweet potato were most preferred. The total phenolics and flavonoid contents of YCAP and BCAP were higher than those of yellow (YC) and black (BC) cheonggukjang prepared without added purple sweet potato. YCAP and BCAP also showed higher DPPH radical-scavenging activities than other samples. Moreover, rat blood plasma samples taken 1 h after oral administration of YCAP and BCAP showed higher inhibitory effects against lipid peroxidation than did rats fed YC or BC. These results suggest that the long-term intake of cheonggukjang prepared with purple sweet potato may increase the antioxidative activity in the blood.