It's also been a topic that's caused some confusion in previous videos I've made.

We're talking about what is the perfect temperature to use when bring a cup of coffee.

How hard should my water be when I'm making drip or filter coffee of any kind?

Espresso brewing temperature is a whole other topic, but I will get to that another time.

Another day today is just about filter coffee.

There is this idea that has persisted that if you use boiling water to make coffee, then it will taste burnt.

You see it online in books kind of everywhere.

I'm not sure that's true. 00:00:57.860 --> 00:01:2.450 Now there is a correlation between brewing water temperature and extraction. 00:01:2.840 --> 00:01:8.120 Generally speaking, the heart of the brew water is the more energy it provides for chemical reactions. 00:01:8.130 --> 00:01:12.160 One of those reaction groups is stuff going into solution and again, certain compounds.

Certain flavors go into solution at different rates at different temperatures, so there's a link unquestionably, but this idea of burning the coffee, this really makes no sense to me.

Coffee beans have been roasted up a 220 degrees C plus.

Often they've experienced really high temperatures.

Ah, 100 degrees.

Seawater isn't gonna further those kind of reactions.

It's not going to cause the coffee to be roasted any darker.

It's not going to create much in the way of flavors the way that roasting does.

What it might do is extract some bitter tasting flavors and burned ashy, smoky tasting things.

If you brew very dark roasted coffee at very high temperatures, that may be where this came from.

But we're gonna take a more rigorous approach today.

I'm gonna investigate what happens if you use just boiled water to make coffee? 00:01:59.540 --> 00:02:2.620 Because we're not gonna just track the temperature inside the kettle's. 00:02:2.730 --> 00:02:5.920 We're gonna track the temperature in the coffee that's brewing. 00:02:5.930 --> 00:02:6.840 We're gonna use a word. 00:02:6.940 --> 00:02:7.620 It's a bad word. 00:02:7.620 --> 00:02:7.960 I'm sorry. 00:02:7.960 --> 00:02:9.250 It's not appetizing word. 00:02:9.630 --> 00:02:14.000 It's amongst the least appetizing words in coffee, though I think Musa Lidge is probably worse.

But we're gonna talk about the slurry right, and the slurry is the grounds in the water as they mix together, either in the top of, say, a brewing cone or inside.

Let's hear French press that combination of coffee and water.

That's the slurry.

That's the temperature I'm most interested in is how this works.

Attached to this thermometer is a small temperature probe going into the grounds, and it's just underneath the grounds right now where we're gonna use it to measure the temperature of the slurry.

Our boy list kettle on that I'll pour a bloom.

This is 30 grams of coffee on, so I'll do a 60 to 80 grand bloom, and I'll wait 45 seconds and then I'll complete the brew.

And during that brute will be able to see how the temperature of the slurry increases and what kind of temper gets up to. 00:02:57.340 --> 00:03:0.450 Even though I'm using this as close to the boil as possible. 00:03:1.810 --> 00:03:2.250 Let's go.

So obviously, this was a pretty heated brewer on the grounds, and there were a little bit warm, but still, the temperature is nowhere near our kettle temperature and bear in mind during a 45 2nd bloom.

For getting to the end of now, this water has cooled down further still, let's keep brewing.

So, as expected, the temperature's coming up and it should be pretty stable now.

Now, then, to the brew at this point were a peak temperature.

What's gonna happen now is that evaporative cooling is going to start to pull some heat out of this.

You can see steam rising that's pulling energy out of the brew constantly and again. 00:03:59.250 --> 00:04:1.210 This slurry this there were mass. 00:04:1.220 --> 00:04:7.730 Is it drained through is getting smaller and smaller and smaller, so we'd anticipate a gentle decline in brew temperature. 00:04:7.730 --> 00:04:10.350 At this point, let's let it drain out.

So there it is.

It didn't even get past 91 degrees Celsius on this kettle, I'll admit, is Capt, actually in 98 degrees Celsius.

But even if I'd got it to 102 degrees more, I might not have got past 93 degrees Celsius in the slurry.

This is a plastic cone.

This was a preheated brewer.

The grounds were a little bit warm.

There aren't many environments that I could have made this Ah, hot Abreu.

And yet this slurry got nowhere near 100 degrees Celsius.

And I think the light roasts you need tohave the hottest water you can get so that your slurry temperature is as hot as it can be.

But I will confess a pore over is a very different thing to a French press.

There's a much slower delivery of water.

There's a smaller thermal mass.

There are a bunch of challenges of maintaining slurry temp here that you might not have here. 00:04:59.250 --> 00:05:1.310 So now the French press, What we're gonna do is very simple. 00:05:1.310 --> 00:05:2.840 We're gonna boil a kettle of water here. 00:05:2.960 --> 00:05:4.650 We've got 45 grams of coffee. 00:05:4.650 --> 00:05:9.050 I'm gonna add 600 grands of water for my 75 grams a liter ratio. 00:05:9.410 --> 00:05:10.230 And what's your happens?

What will happen to the brew temperature?

The probe is in here.

It will be in sort of top of the slurry where it's at its absolute hottest scripts.

Here we go straight off the boil.

600 grounds.

So again, it's only gonna get cooler from here on out.

We were never close to boiling, even though the water was very, very hot.

Now I know you're thinking you're thinking you've got me because was this French press preheated now?

It was not.

Shall we find out what happens if we do?

Preheat the French press.

I think we should.

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I think the square space for sponsoring this video so same experiment all over again, except now is nicely preheated what will it do to the broom temperature? 00:07:9.520 --> 00:07:12.680 So again created as much as I could, I could have gone Maur.

But at what point am I actually getting any sort of return on my investment of temperature?

Little bit hotter, but not a lot hotter.

So it's really pretty much impossible.

Unless you had, let's say, a jewel walled stainless thing that you did aggressively preheated with boiling boiling water.

It's really hard to get to very high temperatures where annual extracts a very bitter, very harsh flavors from medium to light roasts.

This doesn't mean that the highest possible temperature is the best for every single coffee, not at all.

What I would say is, if a coffee is a darker, more developed roasting, you enjoy that.

Know that it's gonna be easier to get those very bitter, very harsh kind of ashy smoky flavors out of them.

Don't brew quite as hot. 00:07:54.020 --> 00:08:3.150 Brewing in essentially the mid to high eighties in terms of Celsius will yield a kind of smoother, less bitter result that should still be plenty extracted. 00:08:3.220 --> 00:08:9.060 If you are getting bitter, burnt kind of tastes, then you can just back off that temperature a little bit. 00:08:9.150 --> 00:08:14.380 But for certainly most specialty coffee, it's really pretty hard to get the temperature wrong.

You've gotta work really, really hard to have a high temperature here.

There's a couple of exceptions to the rule.

I think things like siphons are beautiful, and they can brew incredibly hot on that very high temperatures if you don't pay attention to that.

But broadly, if you're pouring water from a kettle, assumes you can after the kettle's boiled, certainly with medium and with light roasts.

Now, in this video, I haven't really touched on the opposite side of the scale, right?

What happened really blue with cold, cool, tepid water, all of that kind of stuff.

The topic of cold brew is one that is heavily requested.

Obviously, you understand a little bit that you can't extract as much with cold water as you can with hot.

That has a number of implications, and some people think it's a good thing, and some people think that's a terrible thing.

I'll address this in future. 00:08:56.500 --> 00:09:0.670 Don't worry about that, but we're not gonna go into cold brew at any point now. 00:09:1.310 --> 00:09:2.740 Originally, your thoughts on this. 00:09:2.870 --> 00:09:3.980 Is this a surprise? 00:09:3.980 --> 00:09:6.360 Were you expecting a different kind of result? 00:09:6.570 --> 00:09:10.950 Has this made sense of something that seemed oh so confusing to you before?

What a mess.

What didn't I talk about in this video?

What would you like to see me explore further in the future?

I'd love to hear from you.

Leave me a comment down below.

Yes, I think so much for watching I have a good day.