Coffee Machines

[Janus 28]

@apelike

What causes the white coating on top when boiling water has been used?

Edited October 26, 2019 by Janus

[tzijlstra 11]

On 24/10/2019 at 12:02, *Wallace* said:

It’s all personal taste you may hate a certain beer that I may love and vice versa personally I’m after a bean to cup machine around £300 and it should make excellent coffee,you’re spoonful of Nescafé is saving you a fortune,please don’t boil water for coffee though 😀

DeLonghi Magnifica - we're on our second in 12 years. They tend to last at least five years. We will probably need to get our next one soon

 

To answer OP - I like good coffee, a 'Nescafé' doesn't taste like coffee to me. The comparison would be getting a proper pizza from an Italian restaurant or a frozen £2 job from Tesco. The difference is notable!

[apelike 10]

1 hour ago, Janus said:

@apelike

What causes the white coating on top when boiling water has been used?

Probably the coffee additives such as coffee oils and such which are used in the processing to enhance the aroma as instant dried coffee loses a lot of that when processed. TBH I have never seen any white coating on my instant coffee (Carte Noire Classique) and I always use boiling water and add milk last. I always add boiling water to my cafetiere when using ground coffee as well. 

[Pettytom 1]

5 hours ago, apelike said:

No it can't that is just a commonly held myth, and in any case the coffee beans have been roasted already. There is no scientific reason to it at all otherwise we would not have relied on coffee percolators for so long that work by using boiling water. Using boiling water on instant coffee should make no difference at all as it's not coffee solids but coffee solubles that have already been extracted from coffee solids so the taste only varies by how much you put in and how you make it.

 

 

Using boiling water on instant coffee probably won’t make any difference to the flavour, but it certainly will with ground coffee.

 

Quite a few of the compounds that make coffee bitter are difficult to dissolve. The higher the water temperature, the more likely they are to end up in the drink. So using boiling water will give you a more bitter coffee than using water at, say, 90 Celsius.

[nightrider 13]

On 24/10/2019 at 10:42, Padders said:

So yesterday I went for a walk round Meadowhall (like you do), and I came across a shop selling kitchen utensils and stuff, go on then I thought I'll have a look round.

Just browsing when a spotted a coffee making machine,  £999-99p that's less than £1000  Anyway it got me thinking, why doe's anybody want to pay all that money for a cup of coffee..

I get up in the morning, boil the kettle, spoonful of Nescafe, add milk and Hey Presto lovely cup of coffee.. what on earth do they do, Italian espresso, Cappuccino, Latte, Macchiato, Irish, Americano. At the end of the day it's a chuffin cup of coffee...

Is it a class thing, status symbol or something.. You know, look what Iv'e got, knowing full well the likes of me can't afford one.

Anyway just wondered if anyone has got one, are they worth it ? doe's the coffee taste any different 

? Thanks.

I've got one that costs a lot less than £1000, and yes it does taste better.  Nescafe does not even taste like coffee.

[Obelix 11]

On 26/10/2019 at 13:20, apelike said:

No it can't that is just a commonly held myth, and in any case the coffee beans have been roasted already. There is no scientific reason to it at all otherwise we would not have relied on coffee percolators for so long that work by using boiling water. Using boiling water on instant coffee should make no difference at all as it's not coffee solids but coffee solubles that have already been extracted from coffee solids so the taste only varies by how much you put in and how you make it.

 

 

A percolator doesnt drop boiling water on the ground coffee though. It uses steam to push hot water up and over the coffee but the mass of water is a fair bit cooler than boiling so nothing untowards regarding bitterants can occur.

 

If you add boiling water to instant coffee then you steam distill away some of the flavour compounds and again this has a noticeable effect on taste.

[apelike 10]

2 hours ago, Obelix said:

A percolator doesnt drop boiling water on the ground coffee though. It uses steam to push hot water up and over the coffee but the mass of water is a fair bit cooler than boiling so nothing untowards regarding bitterants can occur.

I think you will find that a percolator uses bubbles of water vapour which pushes boiling water up and over the coffee. This is not done just once but many times over to get the coffee to the desired taste. Basically its on a rolling boil For many minutes so the temperature is fairly consistent.

 

Quote

If you add boiling water to instant coffee then you steam distill away some of the flavour compounds and again this has a noticeable effect on taste.

No as the coffee has already been extracted and is basically dead coffee so the flavour compounds are locked in and will not change with temperature. You can change the taste of instant coffee but only by adding more or less excluding any othother addatives.

 

I have yet to find any data or reliable information on what flavour compounds can change by using boiling water. It seems to be a generally held view but with nothing of any scientific value  to back it up.

Edited October 28, 2019 by apelike

[Pettytom 1]

10 minutes ago, apelike said:

 

 

No as the coffee has already been extracted and is basically dead coffee so the flavour compounds are locked in and will not change with temperature. You can change the taste of instant coffee but only by adding more or less excluding any othother addatives.

 

I have yet to find any data or reliable information on what flavour compounds can change by using boiling water. It seems to be a generally held view but with nothing of any scientific value  to back it up.

If the flavour compounds are locked in, why is it that a cup of coffee has an aroma?

 

If you want a detailed account of the chemistry of coffee making, there are several on the Royal Society of Chemistry website. 

[Obelix 11]

1 hour ago, apelike said:

I think you will find that a percolator uses bubbles of water vapour which pushes boiling water up and over the coffee. This is not done just once but many times over to get the coffee to the desired taste. Basically its on a rolling boil For many minutes so the temperature is fairly consistent.

 

No as the coffee has already been extracted and is basically dead coffee so the flavour compounds are locked in and will not change with temperature. You can change the taste of instant coffee but only by adding more or less excluding any othother addatives.

 

I have yet to find any data or reliable information on what flavour compounds can change by using boiling water. It seems to be a generally held view but with nothing of any scientific value  to back it up.

You are wrong on both counts.

 

Percolation is at about 92c at shut off

Go stick a thermometer in one if you want to see.

 

As for steam distillation perhaps you might try reading up about it? I've done steam distillation a few times in a lab so I understand how it works but it's understandable if you haven't

[apelike 10]

2 hours ago, Pettytom said:

If the flavour compounds are locked in, why is it that a cup of coffee has an aroma?

By locked in I mean they are not subject to further processing changes such as heat as they are just extracts and not coffee bean solids. Basically with instant coffee you are in a sense drinking a dried soluble variety of coffee that's already been made.

 

From wiki:

 

"To produce instant coffee, the soluble and volatile contents of the beans, which provide the coffee aroma and flavor, have to be extracted. This is done using water. Pressurized liquid water heated to around 175 °C (347 °F) is used for this process." Notice the temperature for extraction is much higher than water boiling point.

 

2 hours ago, Pettytom said:

If you want a detailed account of the chemistry of coffee making, there are several on the Royal Society of Chemistry website. 

Yes seen some but none explain the chemistry of how the compounds in ground coffee are affected by hot water as some, as far as I know, are only affected by heat higher than  boiling water. They also want you to pay for some articles.

[Pettytom 1]

7 minutes ago, apelike said:

By locked in I mean they are not subject to further processing changes such as heat as they are just extracts and not coffee bean solids. Basically with instant coffee you are in a sense drinking a dried soluble variety of coffee that's already been made.

But boiling water will vaporise some of the more volatile components of instant coffee. It will dissolve others and it will likely trigger reactions between some of the compounds.

 

So the end product isn’t really locked in at all.

 

That’s why making instant coffee with cool/cold water makes an even more unpleasant drink than making it with hot/boiling water

[apelike 10]

1 hour ago, Obelix said:

You are wrong on both counts.

Am I.... 

 

1 hour ago, Obelix said:

Percolation is at about 92c at shut off

Go stick a thermometer in one if you want to see.

That depends on what type of percolator is used as the stove top ones can easily exceed that, as said some can be on a rolling boil for tens of minutes.

 

1 hour ago, Obelix said:

As for steam distillation perhaps you might try reading up about it? I've done steam distillation a few times in a lab so I understand how it works but it's understandable if you haven't

What has steam distillation got to do with it? BTW I do understand it as I have also done some in a lab and at home, I also understand the difference between steam and water vapour that some seem to mix up.