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Jang G.Y.,Chungbuk National University | Li M.,Chungbuk National University | Lee S.H.,Chungbuk National University | Woo K.S.,South Korean National Institute of Crop Science | And 4 more authors.
Journal of the Korean Society of Food Science and Nutrition | Year: 2013

We investigated the quality characteristics of sweet potatoes [Shinyulmi (SM), Yeonhwangmi (HM) and Yunmi (YM) variety] baked and subsequently freeze thawed. Baking was performed with a far infrared radiation oven at 250°C for 40 minutes. Baked sweet potatoes were frozen at -18°C for 30 days, and thawed by a microwave oven for 3 minutes. The crude fat and protein content of HM were higher than the SM and YM varieties. Total sugar, reducing sugar, and free sugar content were increased after baking. Lightness, redness, and yellowness, as well as content of β-carotene, decreased after baking and freeze-thawing. Hardness, gumminess, and cohesiveness decreased during thawing after freezing, except for the YM variety. In a sensory evaluation, appearance, flavor, sweetness and overall acceptance were higher from baking and freeze-thawing the SM variety, instead of the HM and YM variety. From the results, the SM variety is preferred for the production of baked sweet potatoes. Source


Lee G.,National Academy of Agricultural Science | Yoon J.,National Academy of Agricultural Science | Lee M.,Chungbuk Agricultural Research and Extension Service
Acta Horticulturae | Year: 2015

This experiment was carried out to investigate the effects of irradiation quantities of red and blue light emitting diodes (LED) on growth and functionality in leaf lettuce (Lactuca sativa) grown in a plant factory during 2013. The tested cultivar was 'Cheongchima (Nongwoobio. Co. Korea)'. The applied treatments were mixed red and blue LED irradiation quantities: 90/30, 80/40, 70/50, and 60/60 μmol m-2 s-1. Air temperature and day length were 22°C and 12 h, respectively. Leaf weight was high in the 80/40 and 90/30 μmol m-2 s-1 treatments (47.5 and 46.6 g plant-1, respectively). There were statistically significant differences in the number of leaves and leaf width among the treatments. Leaf length was longer in the 90/30 and 80/40 μmol m-2 s-1 treatments than that of the 70/50 and 60/60 μmol m-2 s-1 treatments. Leaf thickness was increased with increasing blue light quantity. Total flavonoids content of 'Cheongchima lettuce' was higher in the 80/40 and 60/60 μmol m-2 s-1 treatments (0.72 catechin mg g-1 FW). Total phenolic compound content was higher in the 80/40 μmol m-2 s-1 treatment (0.76 GAE mg g-1 FW). Summarizing, a gain in leaf weight and yield of total flavonoids and phenolic compound contents was obtained in the 80/40 μmol m-2 s-1 treatment (comprehensive results). These results may contribute to the dissemination of the plant factory growing system and production of functional lettuces. Source


Li M.,Chungbuk National University | Jang G.Y.,Chungbuk National University | Lee S.H.,Chungbuk National University | Woo K.S.,South Korean National Institute of Crop Science | And 4 more authors.
Journal of the Korean Society of Food Science and Nutrition | Year: 2012

This study was conducted to evaluate the vegetative value of sweet potato leaves and stalks by investigating their chemical composition and antioxidant activity. The major minerals were found to be Ca and K. The crude protein content of the leaves ranged from 15.57% in Geonpungmi to 20.34% in Yeonhwangmi, while that of stalks was between 3.71% in Yulmi and 5.97% in Sinchunmi. The total phenolics and flavonoids content of the leaves were about 3.0~4.0 times higher than those of stalks. The levels of polyphenols and flavonoids were high in Geonpungmi leaf and in Sinchunmi stalk. ABTS radical activities were high in Geonpungmi leaf (58.75 mg AA eq/g) and in Daeyumi stalk (14.95 mg AA eq/g). DPPH radical scavenging was high in Geonpungmi and Jeungmi leaves (IC50, 0.11 mg/mL) and in Sinchunmi stalk (IC50, 1.09 mg/mL). Source


Li M.,Chungbuk National University | Jang G.Y.,Chungbuk National University | Lee S.H.,Chungbuk National University | Kim S.T.,Chungbuk National University | And 6 more authors.
Journal of the Korean Society of Food Science and Nutrition | Year: 2014

This study was performed to establish extraction conditions for useful components from sweet potato leaves. Extraction conditions were heating temperature (40∼60°C), ratio of solvent to sample (10∼30 mL/g), and ethanol concentrations (50∼90%). The maximum lutein content was 381.88 μg/g under the following conditions: 81.23% ethanol concentration, 46.75°C temperature, and 25.78 mL/g ratio of solvent. The maximum total polyphenol content was 58.44 mg GAE/g under 67.0%, 53.90°C, and 29.10 mL/g, whereas maximum total chlorophyll content was 769.14 mg/100 g under 93.10%, 69.90°C, and 25.98 mL/g, respectively. The highest antioxidant activity of electron- donating ability (IC50) was 0.582 mg/mL under 64.56%, 54.63°C, and 19.57 mL/g, whereas total antioxidant activity was 32.54 mg AA eq/g under 64.42%, 44.51°C, and 26.01 mL/g, respectively. Under these conditions, experimental data matched well with the predicted data. Consequently, the present study was carried out to simulate and optimize sweet potato leaves for useful component extraction. © 2014, Korean Society of Food Science and Nutrition. All rights received. Source

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