The Carbohydrate Composition of Onions During Long Term Cold Storage

SummaryOnions cv Robusta were cold stored at 4°C and 70% RH at the end of three successive growing seasons from 1978-1980. The carbohydrate contents at harvest, after drying and during storage were measured. The soluble non-reducing sugars present were oligosaccharides, probably a series of fructosans. The only reducing sugars found were fructose and glucose. The main change observed in storage was the hydrolysis of oligosaccharides to reducing sugars. In a storage season of short duration there was a very low fructose content in bulbs at harvest, whereas in a storage season of long duration fructose amounts at harvest were higher. This relationship persisted despite considerable increases in fructose during storage. There was an indication that in any one year the amounts of fructose in bulbs at harvest together with seasonal differences in the weight of the innermost leaf initials could be taken as an indicator of the length of time the onions could be held in storage.