Soluble Carbohydrates in Onion Cultivars Stored on Field Conditions in the South West of Negro River, Argentina

Resumo

Concentrations of soluble carbohydrates were analysed during storage in three onion cultivars (Allium cepa L.): Valcatorce INTA, Grano Oro (both with brown skin) and Antartica INTA (with white skin). These cultivars are produced in the Low Valley Negro River, to internal and external market. Carbohydrates were assessed by Gas Chromatography with Flame Ionization Detector (GC-FID), based in methanol-water extraction 80%. The ANOVA revealed highly significant difference (P<0.001) between cultivars and glucose, fructose, and total carbohydrates. Total sugar compositions throughout storage have scarcely increased after eight weeks and varied within cultivars (P < 0.05). The ratio monosaccharide to disaccharide had a significant cultivar effect (P < 0.001), and over twelve weeks of storage was monosaccharide domineering. Valcatorce INTA had the higest ratio (17.5-13.2); Grano Oro intermediate (12.1-10.9), and Antartica INTA the lowest (4.7-3.5). There was a peak of sucrose level that would be announcing the onset of sprouting four weeks post harvest, which was significantly different for Valcatorce and Antártica (Tukey test P<0.05), and was not significantly different for Grano Oro. These results are evidence of quantitative differences of sugars, due mainly to genetic factors. The implications of quality and storability are discussed.