How do you keep a hot drink at the right temperature?

3 tips to keep your drink hot

1. Use an isothermal mug or bottle

The simplest, tried-and-tested tip is to rely on the best isothermal mugs, mugs and other isothermal bottles designed to keep drinks hot.

Their effectiveness comes from their design: an isothermal bottle actually consists of two bottles separated from each other by an empty space. Strange? Not really, since it’s this empty space between the two walls that prevents the exchange of heat between the outer and inner bottles. The exchange of heat… or coolness, as it prevents the inner bottle housing your precious treasure from coming into contact with the external cold. This is to limit what is known as heat conduction.

Isothermal bottles actually limit everything that promotes heat diffusion: such as conduction, convection and electromagnetic radiation. But we’ll stop there, because the details are far more complex.

The term isothermal comes from the Greek “thermos” meaning “hot”. But this isothermal bottle, thermos or mug doesn’t heat: it simply maintains the temperature of your precious beverage for several hours. Hence the importance of choosing the right temperature right from the start.

Today, most isothermal bottles are available in steel, stainless steel or aluminum. However, the material used has nothing to do with capacity or heat conservation, since the most important factor is the vacuum between the two walls. There are also bottles in glass, plastic and even bamboo, which, let’s face it, is more eco-friendly and aesthetically pleasing.

A little anecdote: the term “thermos” is widely used today, but it mainly refers to the brand name. Just like the fridge!

2. Use metal “coffee joulies”.

Coffee joulies are metal coffee beans which, when added to your hot beverage (coffee, tea, chicory or chocolate), keep it at the right temperature.

Well… the details are a little more complex. In fact, they work in two stages. 1. they’re placed in the bottom of your favorite mug into which you pour your coffee, tea or chicory. Here, their primary mission is to cool your beverage by trapping its heat (so as not to burn yourself!). 2. Then, little by little, the joulies release the stored heat, keeping your beverage at the right temperature for even longer.

Their outer shell is made of stainless steel, and inside? There’s magic! Inside is a phase-change material that enables coffee joulies to “play with fire”. This is a material whose physical state (liquid or solid) changes according to temperature. Each change of state thus generates a change in temperature. A bit complicated, isn’t it? Yes, it’s true, but the main thing to remember is that they’re very practical and make it easy to keep a drink hot.

3. Wrap a cup in a scarf… And why not?

No thermos or coffee joulies to hand? You must have a wool sweater or scarf at home, right? Well, now you know how to keep a drink hot. At least, when you don’t have to go anywhere.

This simple, practical and super-saving tip involves 1. pouring your hot winter or morning drink into your favorite mug. 2. Wrap the mug in a wool scarf or sweater sleeve. Wool insulates your mug (and its contents) for a few extra minutes. And 3. Enjoy.

By the way, what is a hot drink and what are the ideal temperatures?

Yes, because it’s all very well to want to keep your beverage at the right temperature, but you still need to know what that means! Because, depending on the beverage (particularly for tea leaves and other infusions), the right water temperature is essential.

The ideal temperature for tea

To brew your tea or herbs properly, you need heat! This is how the tea will bring out all its flavours, without revealing any bitterness. But to complicate things further, temperatures also vary according to the tea itself:

– green tea should be brewed in water around 70° to 75°C
– black tea between 85 and 90°C, and darker teas at 95°C
– more rare, white tea between 70 and 75°C
– oolong tea at 95°C
– herbal teas can be brewed in water at 100°C

Here we’re talking about an ideal in which to brew your tea. Over a range of 1 to 4 minutes. But it’s best to drink (and enjoy) your tea at around 60°C.

For a coffee

Like tea, the extraction of coffee aromas depends on the temperature of the water. Ideally, an espresso should be prepared at 85 or 95°C. Instant coffee should be blended in water between 80 and 85°C. And a filter coffee in water between 50 and 60°C. But here, we’re talking about preparation. Consumption is a different matter. Coffee should be enjoyed at between 55°C and 65°C to avoid burning, and to fully savor the aromas. However, many people also enjoy it at around 40°C, lukewarm.

And for chicory

Soluble chicory, especially when blended with coffee, should be mixed with water at 80 to 85°C. But once again, we’re talking about preparation here; for tasting: chicory is best enjoyed between 55° and 65°C, like coffee.

Of course, this is an ideal. And to achieve such a degree of precision, so to speak, you need to be well equipped. There are kettles with adjustable temperature…

Finally, remember that 1. Whatever you drink (tea, coffee or chicory), it’s best not to prepare it in boiling water. 2. It’s exposure to air that reduces the temperature. To keep it hotter for longer, you may simply need to add a small lid or stopper to your container.