[ASC-media] NSW DPI research paves the way for classifying mild onions

joanne.finlay at dpi.nsw.gov.au joanne.finlay at dpi.nsw.gov.au
Tue Sep 18 04:05:59 CEST 2007

18 September 2007

NSW DPI research paves the way for classifying mild onions 

Onions that are mild in favour and suitable for eating raw are to be 
labelled as mild under a new system for classifying onions.

Australia?s onion industry has decided to support the development of a 
mild onion certification system following research from the NSW Department 
of Primary Industries (DPI) demonstrating that pungency can be reliably 

NSW DPI postharvest researcher, Dr John Golding, says the lack of a 
reliable, cost-effective test has been the major barrier to date for the 
development of an Australian mild onion industry.

Dr Golding concluded it is possible to consistently grade onions according 
to taste after carrying out research with Food Science Australia in Sydney 
and at the Wagga Wagga Agricultural Institute. 

Using a specially constructed onion press, NSW DPI researchers measured 
levels of the chemical that causes pungency in onions - pyruvate ? in 
1,500 onions. 

These levels were then cross checked against rankings collated from a 
sensory tasting panel and more than 100 consumers.
A trained panel of sensory experts and untrained consumers took part in 
these taste trials, and both groups were able to reliably and accurately 
perceive differences between higher and lower levels of pyruvate. 

?As expected, onions with the lower levels of pyruvate were equally 
?liked? and those onions with the higher levels of pyruvate were equally 
?disliked??, Dr Golding said.

Dr Golding presented the highlights of his research at the Australasian 
Postharvest Conference, held in Terrigal last week.

He also spoke about follow-up research, analysing levels of pyruvate in 
mild onions purchased anonymously over several months from both NSW and SA 
retail outlets. This study found that some onions sold as mild were in 
fact not mild.

Dr Golding said because pungency increases with storage, it is recommended 
that mild onions be consumed no more than 30 days after harvest. 

Pungency also varies with differing soil types and nutrient levels, making 
it necessary to collect onion samples for pungency testing just prior to 

Onions with pungencies close to the limit for the mild classification may 
need to be tested 30 days after the pre-harvest test, while those with 
lower pungency may not need re-testing if sold within 60 days of the 
pre-harvest test.

The research project was facilitated by Horticulture Australia Limited 
(HAL) in partnership with the Australian Onion Industry Association and 
was funded by the onion levy. The Australian Government provides matched 
funding for all HAL?s R&D activities.

Media inquiries: Joanne Finlay on 6391 3171 or 0428 491 813

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