FACED with the grim reality of a declining number of sweet-toothed youngsters, one of Japan’s biggest confectioners is re-tooling itself for the swelling ranks of weak-jawed oldies.

As the greying of Japan’s population begins in earnest because of the plunging birthrate, biscuits and other products are being redesigned with a simple remit in mind: they should look like the original, taste like the original and the first bite should crunch like the original. But after that they must dissolve instantly so as not to strain ageing jaws.

The company, Ezaki Glico, is a global leader in the cutting-edge science of “biteability”. Deep among the bubbling flasks and test tubes of Glico’s central research laboratory in Osaka lies the world’s most sophisticated electronic gauge of a biscuit’s crunchiness.

“From monitoring the tiniest movement in your mouth muscles, we can know more about how you chew your favourite snacks than you do,” a lab-coated chocolate expert told The Times. “Every little peak and trough on this graph brings us closer to knowing the ideal texture.”

For nearly 80 years Glico has been making sticky caramel chews, brittle Pocky sticks and creamy Almond Chocos to the delight of children across Japan. One of its most successful products has been Bisco, a biscuit not unlike a custard cream, which first appeared in 1933.

Three years ago the company introduced a low-protein version of Bisco aimed at what it assumed was the niche market of recovering kidney disease sufferers: it turned out to be a massive hit with older people — but nobody was sure why.

In questionnaires the fans of new Bisco simply said that the low-protein version was “easier on the mouth”.

Toshiko Minami, one of Glico’s senior researchers, quickly realised that the traditional clip meter, which merely tests the force required to bite through something, told her nothing about what happened to food inside the mouth.

So Dr Minami turned to the science of electromyography, which monitors the tiny electrical impulses that control the human nervous system. She produced a readout of how much work each mouth muscle was doing on a given biscuit.

By attaching a dozen probes to the jaw, chin and cheeks of elderly biscuit-lovers Dr Minami can now say for certain what makes one product more appealing to them than another. “With this machine, you can detect what we never knew before,” she said. “We have started to build a profile of the perfect texture.”

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