Quality in New Zealand-grown onion bulbs—a survey of chemical and physical characteristics

A survey of ripened onion (Allium cepa L.) bulbs, collated from field-grown crops in the commercial areas of New Zealand, was undertaken to investigate how the characteristics of flavour precursors, phenolics, sugars, dry matter, and hardness varied. The majority of samples were of ‘Pukekohe Long Keeper’ (PLK) and the early selection of this cultivar, ‘Early Long Keeper’ (ELK). A sample of the white onion ‘Dehyso’ and three Japanese onion cultivars was obtained for comparison. Percentage dry matter (DM %) for PLK and ELK for the 1983 harvest was similar for all sites and averaged 13.4%; total sugars averaged 0.45 mmole/g fresh weight. The white ‘Dehyso’ onions had a higher dry matter percentage (DM%) (15.9%) and a greater proportion of fructose compared with glucose than PLK or ELK onions. PLK and ELK samples collected from one site in 1984 had significantly different DM% and total sugars compared to other sites. There was a significant difference in average fresh weight for bulbs between sites. ...