Processing optimization of onion flakes for home meal replacement type soup

Abstract

This study was undertaken to optimize the blanching process for producing onion flakes generally added in solid type HMR soup. Briefly, peeled and chopped onions were water-blanched at various temperatures and times (50, 60, 70°C/ 1, 2, 3 min), followed by hot air-blast drying (60°C, 9 h). Results revealed that the 50°C blanched treatment had a higher L-value and lower a-value than the 70°C blanched treatment. Moreover, the pH value, Brix, and total phenolic contents of onion flakes showed a dose-dependent decrease with increasing blanching temperature and time. Blanching at low temperature for a shorter time was effective in preventing the browning of onion flakes. In blanching at 70°C, the rehydration ratio was increased according to the increase of blanching time. Taken together, the results of this study reveal that water blanching at 70°C for 1 min is the optimal pre-Treatment condition for commercial processing of onion flakes, wherein the nutritional properties are optimally retained.