This study investigated the antioxidant characteristics of sweet potato according to different plant parts and drying methods. The sweet potato plant parts were divided into root tubers, stems, stalks, leaves, and tips, and the drying methods were freeze-drying and hot air drying. Total polyphenol and flavonoid contents and radical scavenging activity of the sweet potato plant parts were significantly different depending on the plant parts and drying methods. The total polyphenol content of freeze-dried sweet potato leaves and tips were 52.76 and 46.19 mg chlorogenic acid equivalents/g sample, and the total flavonoid contents were 222.47 and 214.12 mg quercetin equivalents/g sample, respectively, and decreased with hot air drying. DPPH radical scavenging activity was higher in freeze-drying than hot air drying and was significantly different depending on the plant parts. The ABTS radical scavenging activity of freeze-dried sweet potato leaves and tips were 43.48 and 44.68 mg Trolox equivalents/g sample, respectively, and decreased with hot air drying. Therefore, additional studies on the functionality of using by-products from sweet potato cultivation are needed.

본 연구에서는 2년간 수원 밭작물 시험포장에서 단옥수수 품종인 고당옥과 구슬옥을 파종시기에 따른 생육 및 이삭 특성을 검토한 결과이다. 1. 고당옥과 구슬옥 모두 파종시기가 늦어질수록 파종에서 출사기까지의 일수가 짧아졌고, 출사에서 수확기간은 증가하였다. 2011년의 출사일수는 43 ~ 53일, 2012년은 44 ~ 54일이었고, 출사에서 수확까지는 2011년은 22 ~ 36일, 2012년에는 20 ~ 34일이었다. 2. 파종에서 출사기까지 생장온도일수(GDD)는 출사 후부터 수확기까지는 약 213 ~ 353oC 범위로 비슷하였으나 파종에서 수확까지의 GDD는 2011년(약 916 ~ 1,067oC)과 2012년(약 911 ~ 1,055oC) 모두 큰 차이가 없었다. 특히 8월 5일 파종에서 등숙기 중의 생장온도일수가 다른 파종시기에 비하여 크게 낮았는데 이는 등숙기의 기온이 상대적으로 낮은 것이 원인으로 판단된다. 3. 파종시기에 따른 생육특성을 보면 간장과 착수고는 파종시기가 늦어질수록 짧아졌으며 7월 말 파종 재배에서 유의하게 짧았으며, 경태는 파종시기가 늦어질수록 유의하게 얇아지는 경향을 보였다. 이삭직경은 고당옥은 4.37mm, 구슬옥은 4.43mm로 차이가 없으나 6월, 8월 파종보다 7월 파종구에서 두꺼운 것으로 나타났다. 4. 이삭무게는 두 품종 모두 6월, 8월 파종구 보다 7월 파종구에서 높고, 7월 25일 파종구를 보면 고당옥은 201g, 구슬옥은 140g으로 높았다. 2년간 단위면적당 이삭수량은 고당옥은 715kg/10a이고, 구슬옥은 677kg/10a이었다. 5. 파종시기에 따른 단옥수수 재배는 파종기가 늦을수록 생육이 지연되고 이삭수량이 감소되는 경향이 있고, 단옥수수 만식재배에 따른 최적 파종시기는 7월 20일 ~ 25일로서, 두 품종 모두 7월 25일에 이삭 수량성이 높은 것으로 나타났다. 7월 20 ~ 25일 파종 시 생육이 지연되고 이삭수량이 감소되는 단점 이 있지만 6월 말에 재배한 단옥수수 보다 습해의 피해가 적고, 수확적기가 짧고 전분축적 시간의 지연으로 수확시기를 연장할 수 있다는 장점이 될 수 있을 것으로 판단되어진다. 따라서 추후 단옥수수 만식재배 시 수량과 상품성 향상을 위한 최적 수확적기, 저장방법에 대한 연구가 이루어져야 할 것이다.

‘전미’는 2009년에 농촌진흥청 바이오에너지작물센터에서 전분용 고구마로 개발되었다. 이 품종은 ‘진홍미’를 모본으로 하고, 99IT55-2를 부본으로 하여 선발되었다. 2001부터 2003 년까지 계통선발시험과 2004년부터 2005년까지 2년 동안 생 산력검정시험을 수행하였고, 2006, 2008, 2009년 3년간 무안 등 전국 6개 도에서 지역적응시험을 수행하였다. ‘전미’의 엽 형은 심장형이고, 줄기 및 잎자루색은 녹색이다. 고구마 모양 은 방추형으로 표피색은 자색, 육색은 담황색이다. 선충 및 덩 굴쪼김병 저항성은 ‘중강’이며, 검은썩음병과 연부병도 ‘중강’ 이다. 전분가는 25.6%로 ‘율미’보다 높고, 전분수량은 6.8 t/ha 으로 ‘율미’ 보다 26% 높다. 총당 함량은 ‘전미’가 3.59 g/100 g, dry weight으로 ‘율미’에 비하여 20%가 높다. 당 종류별로 는 sucrose가 2.53 g/100g, dry weight으로 가장 많이 함유되 어 있다. ‘전미’의 조기재배 수량은 3개년 평균 26.1 t/ha으로 ‘율미’에 비하여 147%로 수량이 증수되었고, 만기 및 적기재 배는 26.2 t/ha으로 ‘율미’ 대비 139%로 수량이 높다. 조기재 배의 경우 주당 상품괴근수는 ‘전미’가 3.0개/주로 ‘율미’와 동일하였고, 상품괴근평균중은 151 g/개로 ‘율미’보다 12% 높다. 또한 만기 및 적기재배의 경우 주당 상품괴근수는 평균 3.0개/주로 ‘율미’ 2.3개/주개보다 많고, 상품괴근평균중은 178 g/개로 ‘율미’ 보다 높다.

‘연자미’는 국립식량과학원 바이오에너지작물센터에서 2008년에 육성한 식용 자색고구마 신품종으로 주요 특성과 수량성을 요약하면 다음과 같다. 1. 넝쿨길이는 284 cm로 길며. 넝쿨색은 녹자색, 잎모양은 심장형, 잎색은 녹색을 띤다. 또한 잎뒷면의 엽맥색은 녹색으로 자색을 포함하지 않으며, 끝잎색은 녹색, 잎자루색은 녹색이다. 2. 괴근 모양은 장방추형으로 껍질색은 자색을 띤다. 육색은 대조품종 ‘신자미’가 농자색인데 비하여 자색이다. 상품성을 좌우하

‘대유미’는 국립식량과학원 바이오에너지작물센터에서 2008년에 육성한 바이오에탄올용 고구마 신품종으로 주요 특성과 수량성을 요약하면 다음과 같다. 1. 넝쿨색은 녹색, 잎모양은 심장형, 잎색은 녹색을 띤다. 또한 엽맥색은 녹색으로 자색을 포함하지 않으며, 끝잎색은 녹색, 잎자루색은 녹색이다. 2. 괴근 모양은 방추형으로 껍질색은 홍색을 띤다. 육색은 대조품종 ‘율미’가 담홍색인데 비하여 농황색이다. 상품성을 좌우하는 표피의 형태는 골파짐이 없이 메끄럽다

This study was conducted to investigate nitrite scavenging and Angiotensin Converting Enzyme (ACE) effects by antioxidant ingredient and the contents of phenolic compounds is isolated and purified from various sweetpotato cultivars. Various sweetpotato cultivars contained 4 phenol compounds including gallic acid, chlorogenic acid, gentisic acid and caffeic acid. The range of total phenol compound contents within cvs. Saengmi, Seonmi, Hongmi and Zami was at 23.0~48.8mg/100g and cv. Zami containing anthocyanins pigment whose total phenol compound content was at 48.8mg/100g was by far higher than the other cultivars. The assay of antioxidant activity using solvent fractionated extraction methods was investigated in various sweetpotato cultivars. Antioxidant activity of ethyl acetate (41.2~86.2%) was much higher than chloroform and butanol. Antioxidant activity from cvs. Sangmi, Seonmi, Hongmi, Shinyulmi, Zami and Sinchunmi was much higher than α-tocopherol well-known as natural antioxidant. Rancidity inhibitory effect about soybean oil of extracts fractionated by ethyl acetate from cvs. Saengmi, Seonmi, Hongmi and Zami was high considerably. Ethyl acetate layer among various solvent fractionated extraction had a good effect on nitrite scavenging rate but not had a effect on AEC inhibitory. Solvent of column chloromatography to isolate antioxidant contents from ethyl acetate layer was even better on 30% (MeOH) : 70% (Water) condition. There are 5 ingredients at HPLC chromatogram and antioxidant activity effect of individual ingredients was slightly better on Rt 11.9 and Rt 16.9 fraction.

“Matnami” is a new sweetpotato variety developed by Mokpo Experiment Station, National Institute of Crop Science (NICS), RDA in 2006, for table use and food processing. This variety was selected from the cross between “Hongmi” and MI9510-12 in 1999. Seedling and line selections were performed from 2000 to 2002. Preliminary and advanced yield trials were carried out from 2003 to 2004. The regional yield trials were conducted at six locations from 2005 to 2006. “Matnami” has cordate leaf, green with purple vine and petiole, elliptic storage root, red skin and yellow flesh color of storage root. The average yield of storage root was 27.0 ton/ha in the regional yield trials, which was 11% higher than that of Yulmi variety. Number of storage roots over 50 gram per plant was 2.6. The average weight of one storage root was 173 gram. This variety is also resistant to fusarium wilt and nematode. In addition, steamed “Matnami” has higher polyphenol contents as 3.3 mg/g dw and higher biological activitiesas, which improve the bioactivity in human. The total sugar content was higher, thereby, sweeter than “Yulmi”. It shows lower (68.6℃) initial temperature of starch gelatinization and slower retrogradation process than “Yulmi”.

Sweetpotato tips are known to be very useful parts as a vegetable because of their high nutritive values and great biomass yield. This study was carried out to select a variety that is suitable to the tips of sweetpotatoes as vegetables. Twenty-two varieties were planted in polyethylene (PE) houses and upland field. The tips were cropped, tested and their tips' external characteristics, quantity, sweetness, toughness and taste were likewise tested. This research found that the external characteristics of the sweetpotato tips were mostly colored green or greenish purple and the leaves were of heart shape. When it comes to texture, the crops from the PE houses presented softer sense than those from the upland field, and due to the blanching, the degree of hardness was reduced by 60 percent. The varieties that presented soft texture after blanching were Yulmi, Geonmi, Hwangmi, Sinchunmi, M301, Eunmi, Juhwangmi, Singeonmi and Gogeonmi. The sweetness, which gives a great influence to the taste, was found to be 3.8 Brix°％ on the average for raw tips of sweetpotatoes cropped in P.E. houses, lower than the crops from the upland field which yielded 4.6 Brix°％. By varieties, those that were commonly high in both P.E. houses and upland field crops were three kinds - Geonmi, Sincheonmi and Juhwangmi. The yield derived was on the average 150 tons/ha, which was considerably high yield, compared to the greens like the Korean leeks, which were repeatedly cropped once planted, like the tips. The investigation into the external appearances, texture, sweetness and acceptability found that the varieties that are suitable for sweetpotato tips production are Yulmi, Geonmi, Hwangmi, Yeonmi, Chinmi and Juhwangmi.

Happymi is a new sweetpotato variety developed from Mokpo Experiment Station, National Institute of Crop Science(NICS), RDA in 2004, which was for the raw eating and processing. This variety was selected from the cross between Chinmi andMA 3 in 1996, seed

Biomi is a new sweetpotato variety developed from Mokpo Eeperiment Station, National Honam Agricultura iment Station (NHAES), RDA in 2003, which was for the utilization as feed and food for storage root ofhigh moisture content andfast fleshed up. This var

Yeonhwangmi is a new sweetpotato cultivar developed by Mokpo Experiment Station, National Institute of Crop Science (NICS), RDA in 2005, for table use and food processing. This variety was selected from the crossing between Mokpo 25 and Yulmi in 1997, Sel

Healthymi is a new sweetpotato variety developed from Mokpo Experiment Station, National Institute of Crop Science(NICS), RDA in 2003, which was for the utilization as food and starch. This variety was selected from the cross between Seonmi and MI9001-12

Juhwangmi is a new sweetpotato variety developed from Mokpo Experiment Station, National Institute of Crop Sciencewasselected from seeds obtained by open polycros of SQ27 used as female in 1995, sedling and line selections were practiced from1996 to 1997,

Lysine is the first essential amino acid for optimal nutrient quality in rice grain. For the narrow genetic diversities of lysine contents in rice, somaclonal variation was the source of mutation in our breeding program. Biochemical selection was conducted using 1 mM S-(2-aminoethyl) cysteine followed by two passages of 5 mM lysine plus threonine in the callus subculture medium. The lysine contents in endosperm of all progenies recovered from the biochemical selection were higher than those of their donor cultivar 'Hwayeongbyeo'. These elevated lysine levels of mutants were successfully transmitted to M4 generation. The lysine contents in endosperm varied 3.85 to 4.80% compare to their donor cultivar 'Hwayeongbyeo' was 3.85%. Three of high-lysine germplasms, Lys-l, Lys-2 and Lys-7 were selected by biochemical selection and rapid screening methods. DNA analysis showed that a new insertion of Tos 17 which mapped to rice chromosome 11 on the high-lysine mutant, Lys-2.