The digital agency Leonardo created the online activity, which will give children the opportunity to vote online, via a free phone number, SMS text messaging or post throughout May.
Visitors to the www.realfruitwinders.co.uk website can select one of three possible new flavours: lemon, tropical or raspberry. The winning flavour will be added to the existing strawberry, orange and blackcurrant range.
The website also features a game, called Fruit Test Dummies, in which players attempt to squash fruit.
The website's voting section is in real time and features a live vote count, which it is hoped will encourage competitive instincts.
Once the most popular fruit and item have been chosen, they will appear in the forthcoming TV spot, which will be created by Leo Burnett.
The online activity will be supported by a TV, press and PR push, as well as on-pack support.
Peter McMahon, a brand manager at Kellogg, said: "We are confident this activity will attract kids to the site and raise the brand's profile. The next Real Fruit Winder brand decision is up to them."
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