YESTERDAY morning, an unassuming, grey-suited Japanese executive did not stop as usual on the fourth floor, but headed straight to the top and into his glittering new office. He has been president and chief executive of Ajinomoto for 24 hours and is only just getting used to the power he now wields.

Whatever you eat — from Thai curry to gravy granules — Norio Yamaguchi now has full control of your taste-buds.

Ajinomoto is perhaps one of the most important firms that you’ve never heard of. The seasoning giant is the leading maker of amino acids; its researchers invented the aspartame artificial sweetener; and it is the globally dominant producer of lysine pig feed. All of these products are bestsellers and contributed to the group’s record profits of 45 billion yen (£234 million) last year — profits made, he points out, despite the rapid ageing of the Japanese population and the accordingly high number of “smaller stomachs”.

But one key product towers above everything else Ajinomoto does. Almost 100 years ago, the company invented monosodium glutamate (MSG) and has reigned supreme as the largest producer of the flavour-enhancer since then. On Japanese dining tables, little jars of MSG have been standard fixtures sine 1909. In China and other parts of Asia, there are cuisines and food industries that would be lost without it. In the West every large food company from Nestlé to Unilever quietly relies on the stuff and uses it to ensure the flavours of their brands.

But health worries and other doubts have always encircled MSG, which has always been sold as Ajinomoto (literally the “root of flavour”) in Japan. Speaking to The Times on his first day as president of the company, Yamaguchi admitted that his company’s most important product had an image problem outside Japan, and accepted that he would have to readjust that. His first task, he said, was to present MSG not as a sinister chemical but as “organic seasoning ” derived from sugar cane.

“We need to explain that MSG is made from fermentation, just like beer, sake, miso, and soy sauce,” he says. “The reason why the Japanese market is full of fermented products is because the Japanese climate is perfect for micro-organism activity. We used to say “Beer from wheat, Ajinomoto from sugar cane” to advertise glutamate . . . the substrates might be different but the processes involved are the same as foods we eat every day.”

The company controls about 40 per cent of the world market and sells only 100,000 tonnes of the product in Japan. The remaining 1.5 million tonnes are sold elsewhere and foreign demand is growing at the rate of about 6 per cent a year.

“There exists a fifth taste that cannot be described by the terms sweet, salty, sour, or bitter,” he says. “This fifth taste is what we call umami, and umami is what MSG delivers. Umami is a fundamental, universal taste, and this is why MSG consumption is growing.”

Perhaps startlingly, he has plans to promote it as a health food. “We’re starting to discover that umami, or glutamate, is not only appreciated by the receptors of our tongues. Human beings may also have receptors in their intestines,” he says, confidentially. “So our scientists are discovering that when glutamate enters the body, these receptors react to it and send messages to the brain that aid digestion. We’re starting to realise that glutamate is more intimately connected to nutrition than we ever imagined.”

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