Why won’t my milk foam?

The problem we have with milk is that drinkable doesn’t necessarily mean foamable. Many people tell me that they find skimmed milk easier to foam than full fat, and yet we know that it is all about the protein when it comes to milk foam. Are these people right? Yes and No.


A great and simple test the quality of your milk is to foam it up and then start to listen to it. That’s right – get your ear right into the pitcher. What do you hear? If your milk is in poor condition then it will sound like a freshly opened soft drink, almost fizzing away in pitcher – this is not good. Every tiny pop is another bubble bursting and your foam is falling to pieces. As you let it sit you notice that out of nowhere there are larger bubbles appearing at the edges of the pitcher. With great milk you’ll only hear a few little pops (though this will increase as you swirl the pitcher) but it should really be very quiet indeed.

Pouring

What has this got to do with full fat and skimmed milk? The answer is down to what is causing your bubbles to burst. It isn’t down to drainage as we see in crema, but the presence of glycerol. Glycerol provides the backbone to our triglycerides in our fat molecules – making up around 4% of our whole milk but only traces in our skimmed milk. When the milk is fresh the glycerol is busy being part of a bigger fat but various things can break it up letting it run free. Free glycerol interrupts the foaming process very effectively causing our bubbles to burst. So full fat milk is more susceptible to this than skimmed. However when the milk is fresh this shouldn’t be a problem for either product.

Often we can trace the problem back to storage. The big enemies of foamable milk is light and heat, so if you get your milk in a clear glass bottle that has been exposed to the morning daylight for some hours before delivery then it is likely to be in pretty poor condition. Again – light is a problem in some cafes where they store it in a glass pitcher in a glass fronted fridge. Store it somewhere dark and nice and cool. Interestingly the longer life fresh milks now come in more opaque packaging than many standard milks on the market. In the UK milk in a supermarket never really has more than 10 days shelf life but I tend to see a sharp dip in foam quality when you get with three of four days of the use by – even though it tastes great with my cereal. Anywhere along the way from cow to cup someone can ruin the milk, so it is hard ever to definitive in saying one dairy is better or worse than another.

Full Fat Contents

We are starting to see more and more “Cappuccino Milks” on the market. Often they have added protein (which we already have plenty of to start with) or in one bizarre case they have removed half the fat and then added thickeners and stabilisers to get the nice thick viscosity of full fat milk. This is also a UHT product which I am not wild about. If we look at the quantity of protein in the milk it is around 3% by weight. However only about 25% of these are whey proteins which are the ones that we are after. If you are choosing a milk for cappuccino then taste, sweetness and a creamy texture are what you are looking for in the raw product but often we just don’t demand the same of our milk supplier as we do our coffee supplier – yet your average cappuccino is way over 80% milk. We don’t think of it as a point of difference – milk is milk right? Try it – go out and buy 5 different brands of milk. Steam them all. How do they perform? How do they taste?

Any questions in the comments….

[tags]milk, cappuccino, milk chemistry, food chemistry, lipids, latte, latte art[/tags]

43 Comments

  1. Hello Jim,

    Nice post, and great blog. What’s your take on the ultra-pasteurized organic milks? How do they compare to “regular” milks?

    Fizzy, rapidly disappearing foam is one of my nemeses. I didn’t know whether to ascribe it to poor technique or bad milk. This post would seem to point toward the latter. It can be frustrating…

    Thanks!

    Howard

  2. It does depend on technique too. If your technique results in larger bubbles then they will naturally be weaker than dense microfoam. Check the dates on your milk, try a few different brands, check your boiler produces enough steam power to get the small bubbles needed for microfoam.

    As long as pasteurisation has been done properly there should be no impact on the milk, organic is fine usually.

  3. hi, have you played with any non cow milks? goat, sheep, yak, human? i’ve been prommised some raw goats milk and i was wondering if it’d be worth a play.
    also, does freezing have an impact?

  4. Goat – yes, Human – er, no.

    Just about any milk with a similar protein content to cow’s milk (3%) should be ok. This goes for goat, sheep, yak, reindeer or whatever you can find at the zoo. I can only presume it is the same for human milk too. Some of the ones with much higher fat contents might be tricky, but I would be more worried about the taste.

    I did once serve someone a goat’s milk capp. It did not go down well….

  5. Hi,
    1. You’ve mentioned “big” fats, do you mean larger molecules?

    2. Also the process of homogenisation playing a role in the breakdown of fat, as the process is appears to be destructive?

    3. Constitution of skim is mostly water, as I am lead to believe… what about the use of cream? Now that’s an idea, perhaps… why be worried about the taste? People love fats, cream is used in all types of cookery, desserts, drinks, cocktails. Dairy in the vast majority of coffee drinkers opinions go well together. Apparently in the US they use half’n’half though unhealthy it would certainly taste good IMHO.

    Pascal

  6. I forgot to ask, is this only on commercial machines that you are talking about? Is there a diffence between steaming and machines ie pressure, no. of holes in steaming wand etc..

  7. Haven’t seen “cappuccino milk” on these shores yet.

    At some point milkfoam will begin to “bubble” on the edges if left to sit, no matter how good the microfoam – in your trials, have you identified an “ideal” time period before this happens? And what milk/milkfat delivered the longest time before bubbling? Or are you suggesting it has more to do with age of the milk than any other factor?

    Human milk… heh… well, here’s an idea, “Ma’am, if you care to contribute some milk for everyone in line, we’ll give you a free refill. Here’s a pump…”

  8. Firstly, slightly off subject, I feel the need to thank Jim/James and Annette for their boundless enthusiasm and knowledge that keeps life interesting for us all.

    Secondly…milk stuff. I feel the need to agree and disagree with this thread. We buy milk from a local farm, near our roastery. The cows are Danish bread Jersey’s so the milk is approaching 6-7% Wholesome.
    ( The UK government have actually been talking about taxing fat in milk…to stop children in inner cities drinking cola or something…)
    Anyway…This milk is trully “old fashioned” and makes my milk based drinks amazingly sweet, although I can’t drink so many a day, otherwise the ripples begin to show etc. yuck!
    In recent weeks the cows have come in their food has changed and I have had to go back to the irradiated blue stuff from the super market, because the milk will take NO air or if it does it will fizz and make large square bubbles. The couple who run the farm (and dairy) have tried pasterising the milk for longer for us, but still we will wait until spring.

    Of all the things you can say about mass market milk (or may be anything) it is that it’s consistent.

    Happy Christmas Mr. Hoffmann

  9. I agree with Peter J. In Australia there are certain times of year where the milk just will not foam.It comes down to the varying diet that cows have in southern hemisphere.(They feed on grass outside all year round) The cow’s diet here in the Northern Hemisphere may be more consistant as they are not eating grass outside all year round. I agree with the storage concerns but I think diet may come into it.

  10. I agree with Peter J. In Australia there are certain times of year where the milk just will not foam.It comes down to the varying diet that cows have in southern hemisphere.(They feed on grass outside all year round) The cow’s diet here in the Northern Hemisphere may be more consistant as they are not eating grass outside all year round. I agree with the storage concerns but I think diet may come into it.

  11. Actually, Mary, my understanding is that, during summer the cows are considerable more stressed – due to the heat conditions, and this has a dramatic impact both upon production and quality.

    I tell my customers that it also has something to do with ‘clover in pasture’ which may or may not be the case, but at least it makes you look like you know what you’re talking about!

    Also, with the extra heat, storage and transportation may well be an issue.

  12. Happy Christmas to you too Peter!

    Ok – here is a quick test if your milk won’t foam. Overheat it and see how it smells. If there is that baked, slightly eggy smell in it then there was the right protein in the milk – as it is an amino acid (cysteine) that contains the sulphur that has been released through the breakdown of the protein (beta-lactoglobulin) as H2S (a not very pleasant gas).

    Of course other proteins are likely to have this amino acid (I can’t pretend to know the amino acid sequence of every milk protein!) but it can only be liberated from whey proteins as they are the only ones temp sensitive below 100C.

    If that makes sense?

  13. Why is it that sometimes my milk will foam properly but then when I pour it on the coffee it starts fizzing and bam, no more foam :(

    I just made 2 cappuccinos. One was perfect, and the other one with the exact same milk fizzled and the foam disappeared.

    By the way, I’m using non-fat milk from the supermarket.

    Thanks in advance,
    Carlos Lage

  14. Just me thinking here, but maybe your textured milk froth started to separate? Sometimes I find that if I let my cap froth sit in the cup, the thicker stuff rises to the top while the creamy microfoam stays relativtely homogenised. With a bit of practice this won’t happen, but in the meantime try ‘splitting’ a bit of milk off into a second jug. This keeps the froth smooth and homogenised, and gives consistent proportions in your drinks (ie you’re not pouring all the froth into your first cap and giving the second one nothing but milk).

    Cheers

    Josh

  15. I have noticed more and more consistently that here in the US (Pennsylvania), regular non-fat milk never foams properly even the first day, whereas organic milk always does. Any idea why this would be?

  16. Hi, im doing a project concerning the foaming of milk, what are the various ways in which triglycerides can breakdown?:
    ‘When the milk is fresh the glycerol is busy being part of a bigger fat but various things can break it up letting it run free.’
    This would be a great help thanks

  17. I’m actually having this exact problem with Horizon Brand organic skim milk(I live in Central Ohio). I wonder whether it could have anything to do with freshness (since my milk is also UHT pasteurized I really have no idea how long it has been sitting in storage/at the supermarket) since it is non-fat. All I can say is that I switched recently due to lack of availability of an organic and local brand that had served me well in the past, but I’ve had a lot of falling cappuccinos since then.

  18. Thanks for this info. I’m an all organic stand in Portland, OR and today my milk wouldn’t foam AT ALL! Your post confirmed my suspicions about the possible storage/transport of the milk. I’m going to talk to my supplier and change if they don’t change their ways. It’s embarrassing to advertise all organic and then have to qualify it because you had to go to the freakin’ convenience store to get milk that will foam!

  19. Thank you so much for this info. I have suspected all along that the culprit might be the milk when I have foaming problems, but the people at technical support for my Saeco machine told me otherwise – descale, try a new o-ring for the wand etc. The milk I have been buying regularly for 3 years has stubbornly refused to foam for over a month now! I’m off to try different brands of milk.

  20. Recently, I’ve been buying American “organic” milk. Some of it claims to be non-homogenized or small batch pasteurized. All of it is labeled as skim milk or non-fat milk. But, all of the “organic” varieties loose their foam relatively quickly. It steams well with a dense microfoam, but quickly dissolves like whipped cream melting under heat.

    The really upsetting part about this is that the factory produced hormone-laden skim milk foams wonderfully and keeps itself up leaving me with a big mouthful of foam to lap up even after i’ve finished my latte or cappuccino.

    Any idea of what the problem may be?

  21. Hello We bottle out own milk right on the farm in glass bottles
    in the summer when cows are on fresh grass it seems to froth much better
    we have been trying to figure out a way to keep the glass bottles
    and get the froth we need
    We do not want to put additives to our milk
    we do not homoginize and produce in small batches at a lower temp
    The inconsistancy can be challenging
    it sems to have something to do with what the cows eat.
    I have read your blog and are looking for answers

  22. Hi

    A very interesting topic to those who love to foam milk for cappuchinos.

    I recently bought a very nifty machine that foams milk at the press of a button. It has been working fantastically well and I have been singing the praises of my new gadget, when ….all of a sudden, no froth! Not even a tiny amount – just plain hot milk! I was horrified to think that the machine was perhaps a gimmick after all and just getting ready to send it back to the supplier, when I considered trying a different brand of milk.

    I was delighted to find that the foam was back with the change of milk and amazed to think the milk can make such a difference!

    Now, I would love to find out exactly why this happened and try to prevent it from happening again. At least we can rule out technique as being one of the criteria!

  23. What great comments for everyone. I too have been sadly disappointed in non-foaming organic milk. I can’t believe it. I just moved to NJ from Germany and while in Germany I never had a problem with milk foaming when using ultra-pasteurized milk. Now I buy strictly organic in the US and have been sadly disappointed that the milk won’t foam. Has anyone figured out why the organics don’t foam?

  24. has anyone tried using raw (unpasteurised) milk? I only mention this because I grew up on a dairy farm, and I’ve always maintained that the uber fresh milk on the farm is superior in flavour and texture to shop bought. Part of this will be that my Dad is a particularly good farmer (looks after the cows well, feeds them well), and has awards from the dairy for milk fat and protein content.
    Homogenising and pasteurising the milk will undoubtedly affect it in some respects, whether these affects will result in differing foaming/ post foam flavour profiles would be interesting to know.
    Next time I’m home, I’ll be sure to nab some milk for my machine.

  25. VERY INTERESTING! In the UK I had been successfully frothing milk with a simple hand frother (wand type thing) and improving my technique all the while. On moving to New Zealand I have found that the milk is very reluctant to froth, instead forming hideously repulsive cumbersome bubbles like there is washing up liquid in there. Its traumatic.
    Reading these comments has been very encouraging. So now I set out to purchase every different brand of milk in this land and will not rest until I can once again achieve my smooth, glossy, sheen delight.

  26. Yes… I use fresh, raw, un-pasteurised, un-homogenized, organic milk from Hook and Son here in the UK and it is very difficult to produce any sort of thickness to the milk suitable for a cappuccino. The milk undergoes its stretching phase but will not fatten resulting in a low quantitiy of thin foam without body. I have been successfully producing good frothed milk and microfoam from my Classic Gaggia but with this type of milk, even modifying my technique, it just will not play ball. I am wondering if milk fat is possibly an inhibitor as it seems unusual that the lower the fat content of the milk the better is the foam.

  27. I wish I’d read your page before thinking my little hand-held battery-operated frother had strangely bit the dust. I tried a brand new frother and still had problems with the whole organic milk I bought at Whole Foods in Chicago! Just weak bubbles, with no nice firm froth! This happened to me a couple times in Berlin and I thought it was just a phase of the moon over Germany. Now I know the milk either wasn’t as fresh as it ought to have been, or it somehow got damaged between the cow and the retail shelf.

    Thank you very much for shedding light on how a questionable quality of milk can prevent good foam. It wasn’t the phase of the moon or Age of Kali Yuga setting in. Shame on Whole Foods.

  28. Where is your stand located in Portland?

  29. Thanks. We have a friend who owns a dairy. We are going to try getting some very fresh milk from their and see if we can have nice fat-full creme AND a frothy cappuccino! Great post.

  30. Thanks for the info but your article doesn’t explain why my fresh unpasteurised milk, straight from the farm, doesn’t froth. We’re in switzerland and lucky enough to be able to buy milk almost straight from the cow ( it doesn’t get much fresher than that!)…so why doesn’t it froth when UHT works perfectly? Thanks

  31. Very Interesting, Nancy!!! I switched to AltaDena, Whole Foods and Trader Joes’s, and all three refused to foam. No lattes for a week…misery.
    I’m now back to Knudsen’s milk. Foams perfectly. I use an AeroLatte, which will foam just about anything, very powerful.
    It may the cows’ diets, pasteurization, or something. Anyway, back to regular supermarket milk from now on. After many decades, I haven’t died from it yet and am not going to give up the wonderful lattes that start my day on the right track.

  32. I taste tested the following three both cold from the bottle and steamed to a latte texture:
    All three steamed well.
    A – Fresh form the farm – Unpasteurised, unhomogenised milk
    B – Jess’ Ladies – pasteurised and unhomogenised milk
    C – Cornershop milk – pastuerised and homogenised

    Pastuerisation didn’t seem make any difference to the flavour, if anything, A tasted slightly… farmy.
    Cornershop milk tasted fine, everyone from Starbucks to barista competitions have been using something similar for years, whether cornershop, Tesco or Dairy Crest, they are all processed to give extended life and no separation.
    The unhomogenised milk tasted delicious, creamy and sweeter than the others. In fairness it is organic, and if you read Jess’ website, she seems to take pretty good care fo the cows too.
    I’m after as little process as possible, and where pastuerisation is both giving longer life (and therefore commercially viable when these small farms wouldn’t deliver small orders to London daily) and removing the risk of bacteria, homogenisation takes just a few shakes and the milk is good to go. Seeing cream in the corners of the bottle is for one thing nostalgic, but another shows the customer that it’s barely processed. Proper milk. Does cost a fair bit more though. However where 8oz is the largest size you do, it goes further.

  33. this article goes someway to explain the effect of the various treatments upon the protein content of the milk :
    http://www.sciencedirect.com/science/article/pii/S0958694604000834
    if we are to use this as a guide then pasteurization of milk has  an optimum temperature of between 72-77 depending upon your interpretation (as this is an article about cheese)
    we found we got bad batches of milk without explanation, this is possibly due to incomplete pasteurization or even over pasteurization.

  34. Wow! Found this blog as a result of a google search. My 6 years of perfect frothing
    fell apart this week, all 6 years with the same machine. Desperate I turned to google for answers…..now I know – it’s the Whole Foods organic skim milk. Phew, thought I had lost my frothing mojo. Off to the store I go, no more Whole Foods organic for me! Yay!!

  35. I like the idea of cappuccinos being ‘seasonal’.

  36. Hey Jim, just came across by doing a search on google for “why won’t my milk foam”. I thought I was crazy in thinking that different brands steam better than others. For instance, I frequently use milk from Costco and I’m able to get a rich, creamy and velvety texture time after time without fail and I’m able to pour some art patterns as well. I ran out of Costco milk and had to switch to Tuscan temporarily and I just can’t get it to steam properly. I checked the labels for both containers and couldn’t see any real disparity among the fat content but didn’t think to check the protein. Thanks for an informative read.

  37. For what it’s worth, we switched to grass fed milk, which was recently added by our local Wholefoods in Philadelphia.  The grass fed does not foam as well as previous corn/grain brands.   I’m not certain if its the milk itself or perhaps it was damaged during delivery/storage.  

  38. just want to ask..is it good if the milk frother jug will keep inside the fridge without milk?lovely

  39. well I am amazed at the number of people with my problem.  My machine never got the
    milk hot enough so I was heating it in the microwave then frothing with a hand held
    wand.  Worked fine for a couple of months, then for no reason at all – no froth.  Bought
    a new wand, that didn’t work either so went back to using the machine – no froth. Am
    now convinced it is the milk.  But have been using Lite milk for years with no problem.
    Will have to now try some different brands given what I have read on your blog.
    Jan

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