WHEN CHECKING out potatoes at your green- grocer in the near future, you’ll rate them by their umami as well as type and freshness.

New varieties of potatoes bred at Invergowrie’s Scottish Crop Research Institute, including Mayan Gold and Inca Sun, have better flavour than their more common relatives, thanks to their umami, a uniquely Japanese concept of flavour that may hold the key to breeding the perfect potato.

Although perhaps not widely known, umami, from the Japanese word for delicious, is one of the five basic tastes along with sweet, sour, bitter and salty. It is umami that gives food its depth of flavour.

The research has just been published in the Journal Of Agricultural And Food Chemistry. Dr Mark Taylor of SCRI, who led the research, says the discovery is a vital step in creating potatoes with better flavour.

“Umami is one of the five main taste sensations. The Japanese are particularly interested in this,” he said.

“There are certain compounds that give rise to this umami flavour; some amino acids and certain ribonucleotides formed during cooking.

“The amino acids interact with the ribonucleotides to give the full umami flavour. They interact synergistically to give beneficial effects.

“At SCRI we have potato varieties called phurejas. They always come out top in flavour assessments by trained panels.

“We wanted to correlate levels of umami compounds with the flavour assessment scores from a range of potato types.

“We found the phurejas always had more umami compounds and there was a correlation with the taste panel score.

“It’s the first time the levels have been correlated with the taste panel data, which is the critical thing,” said Dr Taylor.

The research compared phureja varieties, including Mayan Gold and Inca Sun, with solanum tuberosum varieties, including Montrose, Pentland Dell, Maris Piper and Record.

There was a clear correlation between umami compound levels and potato flavour scores for all varieties, meaning umami compounds seem to be an important component.

Other SCRI researchers have identified volatile compound differences between tuberosum and phureja which may also contribute.

Scotland’s top Japanese sushi chef has endorsed the importance of umami.

Kumiko Hatori, who runs classes in Japanese cuisine, says it is a vital factor for taste and flavour. “Natural flavour is better for me,” she says. “Anybody in Japan would tell you that umami is very important to the taste and savour of food.”

The discovery means that levels of umami compounds can be monitored throughout potato breeding programmes as a quantitative indicator of potential flavour properties.

Traditionally flavour tasting only takes place at the final stages of the long potato breeding process.

“There are several ways this will help us,” said Dr Taylor. “Firstly, it’s really difficult to assess flavour in a breeding programme.

“You cannot put everything to a taste panel—it’s too expensive and time-consuming—but you can measure umami levels easily.

“We can also look at umami levels during storage and tuber development to see whether or not the taste is affected; that is what is happening to your taste.

“Ultimately we would like to know which genes control the process that leads to the formation of umami compounds and can these genes be used in breeding programmes to generate a tastier potato.

“We are now looking at genetics of the umami formation process and also investigating whether or not we will see the same in other vegetables,” he added.

The research reflects findings from a study of tomatoes carried out by Heston Blumenthal’s restaurant and Reading University.

They found vine-ripened tomatoes had higher levels of umami compounds than gas-ripened supermarket varieties.