# Oracle temperature vs extraction yield



## Sweepy (Sep 7, 2016)

Interesting relationship of machine temperature (not water) and extraction yield with the Oracle which I suspect people will say is because the grinder isn't great.

When my Oracle is heated up (on for circa 30mins) and water display shows 93 degrees, extraction has a lower yield than when it's only been on for long enough to bring the water up to temperature (circa five minutes). Sometimes there's a circa 40% difference.

For ages I've thought it was the beans (although fresh from Rave) or grinder settings but now realising neither are likely.

So with this in mind, do I assume the "correct" way to dial in the grinder is with the machine warmer?


----------



## BlackCatCoffee (Apr 11, 2017)

Interesting. How are you measuring extraction yield?


----------



## Sweepy (Sep 7, 2016)

BlackCatCoffee said:


> Interesting. How are you measuring extraction yield?


 So here my inexperience might get the better of me, but I gauge it by means of a measuring glass. I aim for 60ml for a double or 30ml for a single over 9-14 seconds.


----------



## BlackCatCoffee (Apr 11, 2017)

Ahh ok. I understand. Extraction yield is term that has a specific definition in the coffee world.

So as I read it you are getting a different volume of liquid from your machine when its has warmed up?


----------



## Sweepy (Sep 7, 2016)

BlackCatCoffee said:


> Ahh ok. I understand. Extraction yield is term that has a specific definition in the coffee world.
> 
> So as I read it you are getting a different volume of liquid from your machine when its has warmed up?


 Ah ok, mixing up my terms, sorry. Yes, thats correct, the issue is the different volume of liquid.


----------



## BlackCatCoffee (Apr 11, 2017)

I would suspect that as your machine is warming up it is possibly changing the grind you are getting from your grinder and as such it is affecting the amount of liquid you are getting out.

I am nut hugely familiar with the machine you have but I would guess it does not have a flow meter (dose is possibly time based??) and is not giving you the exact same volume of liquid each time. Either that or as the grind is changing through expansion of parts of the grinder due to warmth so the extraction of the coffee is changing and is appearing to be different due to a greater or lesser volume of crema being produced.

In order to get consistent results you need to be consistent with the variables when brewing. If I were you I would allow the machine to get nice and warm and then dial in your grinder. I would adjust your routine so your machine is always on and warm when you come to use it. This should hopefully sort that problem out.

The other thing I would say is that it is best to weigh the output of your coffee as this is a much more consistent way of measuring the output (again down to variation in crema production as the beans age; crema is a lot lighter than liquid espresso and takes up a much larger volume). You can do this by placing a small set of scales under your shot glass when brewing.

I would also suggest you think in terms of a brew ratio. So for example espresso is traditionally considered to have a brew ratio of 2.1 output to input. So if you have a standard dose of around 18g of coffee in your portafilter (you can weigh this easily) you would brew 36g of weigh of espresso out over the course of 25+ seconds.

All this may seem more in depth than you wish to go which is understandable but I would suggest at a bare minimum you dial in the grinder whilst the machine is hot and make the grind much finer in order to lengthen your brewing time. I would aim to brew for between 25-30 seconds for a 2 floz shot.


----------



## Mrboots2u (May 10, 2013)

Sweepy said:


> So here my inexperience might get the better of me, but I gauge it by means of a measuring glass. I aim for 60ml for a double or 30ml for a single over 9-14 seconds.


 If you machine shot running in time or mls?


----------

