Espresso brewing tips from techie guy step by step guide in pics.

Hello Steemers!

Today I want try to show and explain physical side of coffee brew.

By any means all alluring and magical coffee taste it's combination of chemistry and physics processes.
In other words coffee brew is water extraction.

But to get tasty shot you must follow by some basic rules.

• time of extraction
• volume of extraction liquid
• temperature
• flow speed control / pressure

Great post about this moments you can find on Why drink stale coffee? by @justinlaak

In additional I want say, following:

Time of extraction:
Means how long solvent (water) will be in contact with extraction substrate (coffee)
Longer time - more saturated extraction with water dissolving elements.
If you brew longer than 30 sec you will receive bigger amount of caffeine But you also extract more other elements what will make insipid your coffee shot.

Volume of extraction liquid:
Usually it bound with extraction time. It's bring us to concentration of coffee. High concentrated coffee you can get on short extraction time and your shot will be viscous and rich of flavor and intensive taste usually this type of extraction called "Dopio"
If you make a low concentration you receive watery taste of coffee, almost without "body", aroma is also suffering.

Temperature:
Determine how fast extraction will come and some elements dissolve faster on different temps. As results taste also will change from sour to bitter or even harsh bitter.

Flow speed control / pressure
When water drop come on coffee bean crumb it can hold only certain amount of dissolved elements by saturation limit.
And as results if you have a slow flow your extraction will be saturated with most easy extracted elements. Usually they also have a bitter taste.

Anyway time to me stop to be a bore :)

Little article for beginners how to tamp a coffee without magic.

Some of my equipment for this post:

My irrestible coffee owl :)

Measurement glass:

So, I like use "naked" portafilter and usually I use a single shot basket (7g).

You must hear about the 30 lbs pressure it's almost the true, but I have my opinion what one of the major key of tamping is horizontal top of the "coffee tablet".

If you will be interested about physic of this process in a pictures, please let me know about it and I will make another one post.

Flat and horizontal top of "tablet" forming the water distribution over all your coffee. And help to avoid cracks, channels and other tamping issues what you can have.
Pressure must be enough to form a firm "tablet" what don't fall from your basket when you flip your portafilter

Some tools and techniques can be useful for it.

Example on 7g basket, for this I use a "trichter" the local name of this metal bushing.

next steps on pictures:

As you can see tamper is perfectly fit.

And automatic horizontal adjustment

So.. we have excellent formed tablet need just blow out small bites.

And extraction:

I hope my gif will load and you don't downvote me by huge size of image.

Now time to look about more classic basket size 14g I have VST basket, and I can recommend it:

A circular groove helps us to have visual control of grinder coffee amount:

So little bit more pictures of process.

I try to show some finger grip technique. Need place fingers like a triangle and fill by finger tips how tamper touch the basket age. It must happen in same time. If some corner is lift a bit, apply some more pressure by appropriate finger.

as result you must have something like this:

And you make something WRONG if you got something like this, if you have a look from a side:

There some results of brew while I made this post :)

Thank you!
Votes comments are welcome!
(c) Smailer