고구마 경엽을 식품소재로 활용하기 위해 신황미, 하얀미, 스이오우를 수확시기(60, 90, 120일) 및 마디별(1~5, 6~10, 11~15마디)로 채취, 동결건조한 후 분쇄하여 L값과 총 폴리페놀 함량, DPPH 라디칼 소거 활성을 측정하였다. 그 결과, 신황미는 하얀미, 스이오우에 비해 높은 폴리페놀 함량과 DPPH 라디칼 소거 활성을 나타냈으며, 이는 재배기간이 길수록 정상의 순에 가까울수록 높았다. 90일 동안 재배한 후 1~10마디의 경엽을 채취, 2단계 열풍건조법으로 제조한 신황미, 하얀미, 스이오우 경엽 분말의 총 아미노산 함량은 각각 2,469, 3,384, 2,531 mg/100 g, 총 무기물 함량은 각 7.23, 6.54, 7.11 g/100 g, 총당은 각 11.6, 12.8, 18.2 g/100 g, 비타민 E 함량은 3.04, 3.18, 1.52 mg/100 g이었다. 또한 총 폴리페놀 함량은 각각 5.03, 3.90, 4.02 mg/g, ${eta}$-카로티노이드는 75.6, 71.6, 63.1 mg/g이었고, DPPH 라디칼 소거 활성($EC_{50}$)은 각각 0.29, 0.36, 0.33 mg, ABTS 라디칼 소거 활성($EC_{50}$)은 0.12, 0.15, 0.11 mg으로 시금치보다 2배 이상 강한 활성을 나타내었다.
The foliage of sweet potato [Impomoea batatas (L.) Lam] is an excellent source of food material due to the functional components of polyphenol and carotenoid. In this study, the lightness (L-value), polyphenol contents, and DPPH radical scavenging activity of the foliage of Shinwhangmi, Hayanmi and Suioh cultivars harvested after different cultivation periods (60, 90 and 120 days after planting) and according to tip locations (1st~5th, 6th~10th, 11th~15th tips) were investigated. As a result, Shinwhangmi showed a lower lightness value (60 days after planting and 1st~5th tips). The longer the cultivation periods and the closer the tips, the higher the contents of polyphenol and DPPH radical scavenging activity were in lyophilized foliage of Shinwhangmi, Hayanmi and Suioh. In the 1st~10th tip of Shinwhangmi, Hayanmi and Suioh cultivated for 90 days and dried by 2 step hot-air (1st: $70^{circ}C$ for 8 hr, 2nd: $80^{circ}C$ for 4 hr), the polyphenol and ${eta}$-carotenoid contents were 5.0, 3.9 and 4.0 mg/g and 75.6, 71.6 and 63.1 mg/g, respectively. The DPPH radical scavenging activities and ABTS radical scavenging activities ($EC_{50}$) were 0.29, 0.36 and 0.33 mg and 0.12, 0.15 and 0.11 mg, respectively. These antioxidative activities were over two times stronger than spinach.
