Messing around with oil and Crema

Hi, again apologies for the gap between posts.
A very good Christmas was had by all and I hope you can say the same!Having always been told, and read, that the Crema on an espresso was emulsified oils and that the difference between Arabica and Robusta (Crema property wise) was the amount of coffee oils in the bean, reading one of James Hoffmann’s articles on foam and crema came as a bit of a bolt of lightning to me.

I had always known that oils dispersed foam ever since one of my drinking buddies stole a sip of my beer after eating a particularly oily lamb chop resulting in an almost instantaneous loss of head. Since then a game of ‘put the oily finger in the pint’ became part of our weekly attempt to sabotage each others drinking.
So I thought to myself.
What happens when you add oil to the crema of an espresso shot?
Does it disperse quicker?

The Photos bellow tell this story!
(Oil of choice Olive)

Normal Shot
(Bad exposure not under extracted)
A normal crema head

Normal shot from above
Slightly short but just the way I like it

Normal shot with olive oil added
Entry point of the oil

Shot with olive oil under crema
Quite a nice image shame about the dirty shot glass

Olive oil mixed in with crema
The oil seems to have surrounded the crema and given it a certain rigidity. The crema is still there at almost the same level after 20 mins. Very oily to taste.

Oil mixed with crema slightly closer

Shot made from olive oil mixed with coffee grounds
(what a mess it made of the machine, excessive cleaning required before the next shot)
Very strange brew came out of the machine here, white liquid with a bright white crema and an underlying layer of oil. The oil mix probably stopped the coffee being extrated properly. Very thick in consistency, horrible to taste!

Top of the same shot from above
Crema is lighter with a blob of oil in the middle. Still lasted a long time, no noticeable speeding up of the dissipation.


Next, mixing the oil with the whole beans
Ahh what fun, making the oiliest beans imaginable

Espresso poured from the mix above
There seems to be no effect on the crema although extaction was took a little longer and the grinder needs a good clean.
Pretty nomal looking shot

Has anyone else done such a madcap ‘experiment’?
(I use the word experiment in the mildest possible way)

Can anyone else shed any light on any of this?

All the best and happy coffee drinking

Stu

This mornings Latte
(Not quite on form with the pour but what the hey)

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