The correct temperature for making tea and coffee remains a hotly debated subject. Green and white teas don't respond well to boiling water and every coffee has its temperature "sweet spot". Ian Boughton is stirred to get to the bottom of of what makes an enjoyable brew
The news that Marco Beverage Systems has been working with 2007 World Barista Champion James Hoffmann to create a new kind of super-controlled water boiler has stirred the beverage sector, and brought back to attention the importance of brewing temperatures.
This is something widely debated in espresso coffee but often missed everywhere else - most staff still heat water to boiling, which is not necessarily right for tea and can ruin cafetière coffee.
The danger was neatly described recently by the AA's top repair patrolman while judging a roadside café contest. He reports: "About 70% of cafés got it right, with tea that was ‘sippable' to start with and we could drink it immediately or within a couple of minutes." The worrying thing is that 30% got it wrong.
There are two considerations in beverage temperature - oneis that a too-hot drink is uncomfortable. The other is that one degree either way can completely change the character of tea or coffee being served.
In tea, one big hazard is the general belief that it should be made with a "rolling boil" of large bubbles in turbulent water. The second is of espresso machine salesmen who recite the standard phrase that "the machine will produce boiling water for tea".
All tea should not be brewed at boiling point. A fine green tea should be brewed very low, maybe as low as 70°C, while a white can be brewed at 80°C, and oolong a little higher. Black tea can be hotter, but arguments rage over how much - even the Tea Council says that water must be "boiling", and agreement comes from two very unlikely allies, Teapigs and Tetley.
"There is no getting away with it," says Teapigs' taster Louise Allen, "black tea requires freshly drawn water at 100°C. And nothing beats a temperature-controlled kettle, because although some catering boilers can manage 100°C, the water sits in the tank for some time and is repeatedly bought to boiling point, which is not good for tea."
At Tetley, brand development manager Peter Haigh also believes in the boiling-point. "The hotter the water, the faster the leaves open and the better brew you achieve," he says. "It is not always feasible to use freshly boiling water in the hospitality industry, but we do recommend that you use it as hot as possible."
However, Teapigs and Tetley are in a minority. Jane Pettigrew, probably the most famous of all Britain's tea teachers, sets the figure lower. She advises: "All black teas should be brewed at the same temperature, but given different steeping times - about a minute longer for a larger leaf tea. For black teas, set your boiler at 95-96°C.
"So a catering area really needs two boilers, with the other at 70-75°C, and these will be fine for pretty much all teas. If it is not possible to have two, then for white and green teas, train staff to draw off some water from the 95-96°C boiler and put it into a jug to cool - use a thermometer to check that the water is adequately cooled."
The thermometer is vital, agrees Andrea Stopher, trade marketing manager at Twinings. "For greens, whites and oolongs, boiling water is too harsh on the leaf and brings out the bitter tannin taste rather than the soft, sweeter character," she says.
"Have your staff taste a green Sencha brewed at 90°C, and then one brewed at 70°C - they'll quickly understand why a thermometer is an essential piece of catering equipment."
At Mighty Leaf Tea, one of the companies which has pioneered the new kind of big tea-bag suitable for large-leaf tea, managing director Alan Mellor believes in water just off the boil. "Even the very highest of high-end hotels have practical difficulties with this. It is the grade of the black tea that is significant - many tea-bags are either dust or at best fannings, and these small particles have a huge surface area and infuse very quickly, hence the flat taste. Leaf tea infuses more slowly, and hence the much more complex flavours.
"We always stress that green and white teas should definitely not be made with boiling water. A practical tip is to put boiling water into a cold jug and then into the cold pot with the tea - it will be about right."
And do not draw water for tea from your espresso machine, says Steve Penk, marketing director of La Spaziale espresso machines. "The idea that an espresso machine also provides hot water for tea comes from sales people who don't know a thing about brewing parameters.
"The water comes from the reservoir of an espresso machine, and it is supercharged, so it comes out at about 120°C - far too hot for tea. Don't do it unless you have a bypass on which you can set the water temperature."
There is another reason for cooler tea. The British Medical Journal reports Australian research that drinking a great deal of tea, too hot, increases the risk of cancer of the oesophagus. The Queensland Institute of Medical Research comments: "We should follow the advice of Mrs Beeton, who prescribes a 5-10-minute interval between making and pouring tea."
In the coffee sector, a similar problem exists. There is still a tendency for some catering staff to bring water to the boil and slosh it into a cafetière, whereas the Marco/Hoffman theory for the machine dubbed the "Uber-boiler" dictates that every coffee has a "sweet spot" which should be recognised and respected.
"When I first started in this business, I was taught that you ‘take the pot to the kettle for tea and take the kettle to the pot for coffee'," says David Latchem managing director of Café du Monde. "It was simplistic, but illustrated the point that tea requires slightly hotter water than coffee. Water straight from the kettle is a degree or two below boiling, but by the time you have taken it to the coffeepot, it is in the region of 96°C."
By comparison, the Bunn 392 pourover is set to brew at 92°C, and at First Choice Coffee business development manager Malcom Buckenham makes the point that the brew temperatures for filter coffee tend to be higher than espresso at 92-94°C. Rombouts says its One Cup filter coffee should be brewed at 93°C, and comments that a margin of plus or minus three degrees is probably reasonable before the consumer notices a difference in taste.
But not in espresso. "A difference of half a degree in espresso is noticeable to just about everybody," says David Cooper of Cooper's in Huddersfield, whose promotion of temperature control in Dalla Corte espresso machines started a major debate in the café world. "Grab a man off the street, give him espressos at 89°C, 89.5°C, and 90°C, and he will be able to tell you there is a difference.
So this is not just a matter for coffee geeks. Having said that, with a good coffee blend, you'll find that 92°C isn't a bad yardstick."
Tristan Stephenson, a trainer for Diageo and former bar manager for Fifteen and a finalist in this year's barista championship, recently confirmed this more dramatically. He was testing a blend of Colombian, Honduran and Sumatran supplied by Origin coffee of Cornwall, serving it at 91°C - until he started playing.
"We altered in steps of 2°C at a time. At 86°C the difference was drastic - the acidity of the blend dropped and was replaced by an earthiness of sweet warm soil, because the lower temperature was highlighting this characteristic of the Sumatran Lintong in the blend. At 88°C, that earthiness turned to fruity nuttiness.
"At 90°C, the South American in the blend was beginning to take over with a lightness and more punchy acidity. At 92°C, I was shocked at how light it had become, and we were losing the earthiness of the Sumatran. We eventually found the best balance at 89°C."
And that, say the experts in both tea and coffee, illustrates what every caterer must do regularly - test and taste at different temperatures to find the "sweet spot" of your house coffee and your teas, and then stick to it. Without doing so, you may serve so-so drinks - but in doing so, you may serve great ones.
[Café du Monde](http://www.cafedumonde.co.uk) 01322 284804
[Cooper's ](http://www.cooperscoffee.co.uk) 0800 298 2802
[First Choice Coffee ](http://www.firstchoicecoffee.com) 01908 275 520
[La Spaziale](http://www.laspaziale.com) 01246 454400
Marco Beverage Systems
[Mighty Leaf Tea ](http://www.mightyleafteas.co.uk) 01377 217793
[Rombouts](http://www.rombouts.co.uk) 0845 6040188
[Teapigs](http://www.teapigs.co.uk) 0208 568 2345
0845 606 6328
[Twinings](http://www.twiningsfs.co.uk) 01264 348181
[UK Tea Council 020 7371 7787