Effect of Mild Heat Treatments Prior to Air Dehydration of Dried Onions Quality

열풍건조 전 순한 열처리가 건조 양파의 품질에 미치는 영향

  • Published : 1990.10.01

Abstract

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 $50^{\circ}C$.

Keywords

onions;browning reaction; pyruvic acid content;response surface methodology (RSM)