Effect of Anoxia on Respiration Rate (Fermentative Index) and Ethanol Production of Onion Bulbs (Allium cepa L.)

Abstract

The physiological behavior, including carbon dioxide production, fermentative index (FI) and ethanolic production of onion bulbs kept under total anoxia (l00% N2) was investigated. During the first 24 hours, carbon dioxide production increased from 0.01 to 1.56 kPa Co2, and the average rate of the increase in CO2; production between 0 and 24 hours was 0.09 kPa/h. The Q10, of the fermentative index was l.9. Ethanol produced by onion bulbs kept under anoxia during 6 hours was temperature dependent, and was 0.563 and 0.760 pmol kg-1h-1 at 10 and 20°C respectively, while at 4°C the quantity produced was not detected. It is concluded that onion seems to be less tolerant to anoxia than other vegetables such as artichoke, cauliflower, tomato, potato and asparagus.

Keywords

• anoxia, fermentative index, ethanol, onion, storage conditions.