Frothy physics for a coffee & science evening

A full line up of milk froth! How did each type of milk compare? And why….?

Last Tuesday saw the first of what will hopefully be an autumn-winter series of “coffee & science evenings” at Amoret Speciality Coffee in Notting Hill. These evenings are designed to be conversational; spaces where people can get together and chat about the strange things that they have observed in their coffee (or perhaps the common things that link to stranger things).

The event last Tuesday was in the latter category. We have all seen milk frothed, and noticed how it is different in different milk types (cow and plant), or seen how some foams seem to age while some seem to last forever. But why are some foams stable while others age? And what is the additive in the “Barista edition” oat milk that encourages better foaming and is connected with the foams that you can sometimes see washed up on the beach after a stormy sea?

The oat milk barista edition saw considerable ‘ripening’ of the foam structure as it aged. But does it matter?

We were joined for the evening by Prof. Jan Cilliers of the Earth Sciences department at Imperial College. Why would a professor of Earth Sciences be interested in foam? Well, part of his research involved understanding the use of foams in the froth flotation technique of mining. You can read more about that here. How does it link back to your cappuccino? You can watch some more milk foams age to investigate.

Finally we had the foam line up. Sadiq Merchant of Amoret prepared a series of 8 milk foams using homogenised full-fat milk, non-homogenised full fat and semi skimmed milk, the non-homogenised full fat milk that is used at Amoret, a lactose free milk, coconut milk, oat milk and oat milk Barista edition. The differences were fascinating. That the semi-skimmed milk produced a good stable foam was explicable with its fat-protein content, but why did the lactose-free milk foam so much? Regular oat milk performed fairly poorly: a foam that quickly aged and returned to liquid, but the barista edition oat milk did not last too long either. After 15 minutes there was considerable ‘ripening’ of the microfoam into larger bubbles (as you can see in the photo), but will most coffee drinkers be aware of this? Many of us will have finished our coffee within 15 minutes and be ordering our next one!

More events soon! Sign up to the events list or send an email to find out more.

Our next event on 22 October focuses more on the espresso part of the coffee. What makes a good crema? What are the connections between pulling an espresso and soil science, what can we learn about irrigation and soil ‘health’ by thinking about coffee? What about the grind size distribution? And can we make a connection between pulling an espresso and an old method of measuring blood pressure? (though the question here is not really can we, that answer is yes, the question is should we).

If you are in London, do come along on Tuesday 22nd October, you can sign up for that particular event here or sign up to the events list (to hear of future events) here. If you are not in London but still want to join the conversation, you are welcome to add comments here, head over to Facebook or see you on Twitter.

Leave a Reply

Your email address will not be published. Required fields are marked *

*

*