Georg J. Riedel is constantly striving to find out more about how wine tastes to drinkers. His family has been making wineglasses since 1756, and the Austrian is best known for developing glasses whose shape enhances the taste of wines made from certain grape varietals. But it's not just wine whose taste changes according to the shape of the glass from which it's drunk, he says. Water's taste also changes, as he demonstrated at the Wine & Dine Festival on Hong Kong's Central harbourfront. We have five senses: sight, taste, touch, smell and sound. Many of us rely on taste when it comes to food and drink, Riedel says, but it turns out it is the least reliable sense. According to taste researcher Linda Bartoshuk, people have different amounts of taste receptors, or tastebuds, on their tongues; about half the population has 200 to 400 taste receptors per square centimetre, while 25 per cent are called “supertasters” because they have up to 1,000; the remaining 25 per cent are “non-tasters”, who have less than 200 taste receptors per square centimetre. When we drink wine, Riedel explains, we rely on smell as part of our sensatory evaluation. But what happens when what you drink has no aroma - water, for instance? He takes a bottle of mineral water that's cold, because we can measure temperature difference on the palate, pours it into a lipped glass and asks me to drink it. Thanks to the shape of the glass, the cold water flows to the front of the tongue and the sides, leaving these parts of the mouth much cooler than the rest. He pours the water into a second glass that has a narrow opening and watches me drink it. Because of the narrower rim, I have to tilt my head back a bit more than when using the first glass, and the cold water flows to the back of my mouth. “These two glasses don’t allow flavour onto the palate,” he says, referring to the main part of the tongue. When I drink water from a third glass that has a larger rim, the cold water immediately washes over my entire tongue, filling my mouth; I feel refreshed. “It’s like the tongue takes a bath,” he says with a knowing smile. “The flow of water depends on the shape, size and opening or rim diameter of the glass. The longer it stays on the palate, the more satisfying it is.” Lastly, he gets me to try water from a curvaceous glass that is narrower at the bottom. Immediately the water has a saline taste because the shape of the glass brings out the water's minerality. “Congratulations,” he says. "You’re one of the supertasters. Not everyone can taste that.” I'll be thinking a lot more about how I drink water from a glass, and about the glass, too, after this.