Posted by kathryn in Vegetables

Researchers in Australia are trying to work out what makes one onion taste stronger than another. While red onions are often chosen for their milder taste, variety is not a reliable guide to the sharpness of an onion’s flavour.

This work is a big deal in the onion industry where “mild onions” have become the holy grail. Scientists and farmers have joined forces on the project and Food Science Australia have even been running consumer taste tests.

Over the course of an hour raw onions were fed to ten professional “super-tasters” and over 100 members of the public. While there was a ten minute gap between each test, tasters had to chew and swallow chunks of raw onion, with no spitting out allowed. Volunteers were paid for their work, but even so . . .

From this research we now know people prefer their raw onions mild. However, more significantly for the industry, the testers perception of taste correlated with the level of pyruvate in the onion. Researchers have also developed a pneumatic onion press, enabling them to detect how much pyruvate is in different onions.

Pyruvate is a compound that occurs naturally in onions. Levels are affected by both the conditions in which the onion is grown, as well as how long the onion has been stored for.

The craze for putting slices of raw onions on sandwiches and salads isn’t just an Australian phenomenon, instead it’s considered a worldwide growth sector – hence the onion industry’s interest. However, switching over to mild onion growing isn’t necessarily that easy. Among the complicating factors for farmers is the sulphur content of conventional fertlisers, which actually increases pyruvate levels.

22 September, 2007