열풍건조전 증류수에 침지온도(20, 40 및 $60^{circ}C$)와 침지시간 (6, 12 및 18분)에 따른 열풍건조양파(4% 수분도: 습량기준)의 갈색화 반응과 pyruvic acid 함량에 미치는 영향을 반응 표면 분석법으로 조사하였다. 나타난 수치들을 또한 이차 다항 회귀 모델로써 예측하였다. 이 실험범위에서 침지 시간보다 침지 온도가 갈색화 반응과 pyruvic acid 함량에 큰 영향을 미쳤다. 갈색화 반응은 $50^{circ}C$로 열풍건조시킨 대조구(O.D.=0.168)와 비교하여 $50^{circ}C$의 열풍건조 중 최소화시키는 공정(O.D.=0.071)으로 $60^{circ}C$의 침지온도에서 18분간의 침지 공정이었다. 또한, pyruvic acid 함량은 $50^{circ}C$로 열풍건조시킨 대조구 $(24.08{mu}mole/g;onion;solid)$와 비교하여 $50^{circ}C$의 열풍건조 중 최대화시키는 공정 $(39.85{mu}mole/g;onion;solid)$으로는 $60^{circ}C$ 침지 온도에서 12분간의 침지 공정이었다.
The effects of immersion temperature $(20,;40;and;60^{circ}C)$ and immersion times (6. 12 and 18 min) in a distilled water prior to air dehydration upon the browning reaction and pyruvic acid content of air dried onions to a 4.071 moisture content (wet basis) were analyzed by a response surface methodology (RSM). Those values were also predicted by using a second degree polynomial regression model. Immersion temperature had more influence to browning reaction and pyruvic acid content than immersion time in these experimental ranges. The processing conditions to minimize the browning reaction of dried onions at $50^{circ}C$ of air temperature (O.D.=0.071) were $60^{circ}C$ of immersion temperature and 18 min of immersion time compared to control (O.D.=0.168) of air dehydration at $50^{circ}C$ Pyruvic acid contents of dried onions at $50^{circ}C$ of air temperature were maximized $(39.85{mu}mole/g;onion;solid)$ at $60^{circ}C$ of immersion temperature and 12 min of immersion time compared to control $(24.08{mu}mole/g;onion;solid)$ of air dehydration at $50^{circ}C$.
