Abstract
Physicochemical properties and gelatinization patterns of defatted and lipid-reintroduced moist (Hwangmi) and dry (Suwon 147) type sweet potato starches were investigated. Starch granules of sweet potato were polygonal and round, and the sizes of starch granules ranged $5{\sim}13\;{\mu}m$. All starches showed Ca type in X-ray diffraction but relative crystallinity was decreased by defatting and reintroduction. The amylose content of defatted starches increased, but that of lipid-reintroduced starches decreased. The swelling power and solubility at each temperature increased by defatting, but decreased by reintroduction. Transmittance of Hwangmi and Suwon 147 showed a rapid increase at $60,\;65^{\circ}C$, respectively. The initial pasting temperature by amylograph of Hwangmi and Suwon 147 were $67.5^{\circ}C\;and\;72.7^{\circ}C$, respectively. The peak viscosity and the height at $50^{\circ}C$ on amylogram of Hwangmi were lower than those of Suwon 147. Hot paste viscosity and setback decreased by defatting but setbak and consistency drastically increased by reintroduction. The peak temperature for gelatinization by the DSC was $65.7^{\circ}C$ for Hwangmi and $68.5^{\circ}C$ for Suwon 147. The gelatinization temperature and enthalpy of the DSC decreased and amylose-lipid melting peak was lost by defatting. The gelatinization temperature and enthalpy decreased by reintroduction.
점질인 황미와 분질인 수원 147 고구마 전분을 99% 메탄올로 탈지하고 추출된 지질을 첨가한 다음 이화학적 성질과 호화특성을 조사하였다. 전분입자의 모양은 다각형과 둥근형이었고, 크기는 $5{\sim}13\;{\mu}m$이며, 결정형은 모두 Ca형이었고 탈지나 지질 첨가 후 결정강도는 감소하였다. 아밀로오스 함량은 탈지 후 증가하였으나 지질 첨가 후에는 감소하였고, 물결합 능력은 증가하였다. 팽윤력과 용해도는 $55{\sim}60^{\circ}C$에서 급격히 높아졌고, 각 온도에서의 팽윤력은 탈지 후에는 증가, 지질 첨가 후에는 낮아졌다. 광투과도는 황미가 $60^{\circ}C$, 수원 147이 $65^{\circ}C$에서 급격한 증가를 보였고, 아밀로그라프에 의한 호화온도는 황미와 수원 147이 각각 $67.5,\;72.7^{\circ}C$였고, 황미의 최고점도, 냉각 정도는 수원 147보다 낮았고, 탈지시 최고 점도, hot paste viscosity, setback은 감소했고, 지질 첨가후에 최고 점도는 감소했으나 setback과 consistency는 크게 증가하였다. DSC에 의한 호화온도는 황미와 수원 147 각각 $67.5,\;68.5^{\circ}C$였고, 탈지 후에는 호화온도와 엔탈피는 낮아졌고, amylose-lipid melting peak는 소실되었으며 지질 첨가 후에도 호화온도와 엔탈피가 낮아졌다.
(Department of Food and Nutrition, Chonnam National University)