Cream Rising: A Primer on Milk Fat

This post is part of Real Food Wednesdays hosted this week by Kelly the Kitchen Kop. Be sure and check out all the links for more great Real Food posts. And now, on to the post…

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Cream rises.

O.k., you knew that already. But did you realize it keeps rising?

What? That’s right, the cream on top of your Real Milk keeps rising. Cream is made of up tiny fat globules that weigh less than milk. These globules continually float to the top of the milk. Cream keeps rising to the top as long as the milk sits undisturbed.

And the longer it sits, the more the fat globules crowd together at the top of the container and the less space they take up. This makes it hard to measure cream in volume. The volume cream takes up is always getting smaller and smaller.

How much cream should I get?

Even though the volume of cream in milk is continually changing, there are some general rules you can use at home to check the volume of cream on your own Real Milk.

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Summer Cream Line after 36 Hours

We store our milk in 1/2 gallon mason jars. After the milk has been filtered and refrigerated for 12 hours, you can expect to see a cream line  around the 6 cup mark on the jar. This equates to approximately one quart of cream per gallon of milk. Remember, the longer the milk sits in your fridge, the lower the volume of cream you will have, even though the actual amount is the same. Those fat globules really like to be close.

Someone is skimming my cream!

Well, not necessarily. I did say that a quart per gallon is a rough estimate. The amount of cream varies based on three main factors:

  1. Breed. A Jersey cow gives more cream than a Holstein. Milking Shorthorns & Guernseys fall somewhere in between. And beef breeds are purported to have the richest, creamiest milk of all. No one knows for sure since there aren’t too many folks that milk beef cows and if they did, they would certainly keep all that rich milk themselves!
  2. Stage of lactation. Depending on how many months since calving, the cream content of milk varies. The farther into a lactation cycle, the more cream. This makes sense since calving naturally occurs in the Springtime when the weather is warmer. As the season progresses to Autumn and Winter, so does the cows lactation. Of course, many dairy farms no longer follow a natural calving cycle. Still, the cows’ lactation seems to follow this rule.
  3. Time of year. Yup. that’s right. You get more cream at certain times during the year. It is a seasonal thing. In warm weather, a cow produces less cream. In cold weather, more cream. Why? Think about it this way: fat is a high energy food. A calf needs to stay warm in the winter and would need more fat to produce that warmth. Hence, more cream on your milk.

In the wintertime, we’ve seen as much as a quart and a  half after 12 hours!

We used to think feed had something to do with cream content. Some say alfalfa produces more cream. Others recommend sunflower seeds. But we have not found this to be the case. Cream content is tied to breed, lactation, and season, not feed. This study, done back in the 1930s, confirms this fact.

So where can I get heavy cream?

There are technical definitions for the term heavy cream but I’ll stick with what I know from actually working with cream.

The heaviest cream is found at the top. Remember that milk fat globules are continually rising, constantly trying to get to the top,  squeezing together tightly and leaving no space for the milk. It follows that the densest concentration of fat globules will reside at the very top of your milk. So the very first scoop of cream off the top of your milk is what I call heavy cream.

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Lifting the Heavy Cream Layer from a Jar of Milk

You can actually lift this heavy cream off in a layer. Note how this heavy cream forms a sort of glob that clings to the cream ladle.

When making butter, you get the highest yield (as much as 11 ounces per quart) from the heavy cream.

The deeper you go into the cream, the less dense the fat globules. This is where you find light cream. The very last part of the cream you skim is half-and-half. That’s because it gets harder to scoop out just cream and easier to get skimmed milk in your scoop.

Traditionally, milk was placed in wide pans to cool and rise before skimming. This gave ample room for the heaviest cream to form and maximized the heavy cream yield.  Cream has always been highly valued. Therefore the term “cream rises to the top” in reference to the upward mobility of  human excellence.

Why stay away from Heavy Cream at the grocery store?

You cannot purchase real heavy cream at the grocery or health food store these days. This is because the industrial cream separation process produces a consistent thickness. The cream is separated rapidly from the milk using a machine and not allowed to rise naturally. To produce a what sells for heavy cream, even the organic producers must add thickeners like Carrageenan to simulate naturally risen cream. And most heavy cream is Ultra Pasteurized, a process that destroys a great deal of the nutritional value of the cream.

Cream as Currency?

Cream was traditionally very valuable. In centuries past, people understood their was significant nutrition in cream and went to great lengths to obtain it. Foods made with cream were called rich. If a food was thick and smooth, regardless of ingredients, it was called creamy.

Perhaps we should consider putting the U.S. economy on the Cream Standard.


11 Responses to “Cream Rising: A Primer on Milk Fat”

  1. Real Food Mama Says:

    I love the idea of being able to skim my own cream from a nice fresh jar of raw milk! Unfortunately, I simply do not have the space for dairy cows. However, I will be getting some goats shortly and am looking forward to experimenting with this “naturally homogenized” milk. Perhaps I will be lucky enough to get enough cream to support my habit!

    Thanks for sharing the pics – it looks delicious.

    – RFM

  2. Alyss Says:

    What an informative post! There is one local dairy around here that sells pasturized (but not unpasturized) “whipping” cream with no additives. In fact, they don’t list an ingredient list at all because the name Whipping Cream is the ingredient list. I have to search for it, but I love buying some when I do find it :)

    Someday I’ll have my own dairy cow and won’t have to search….

  3. Pop Says:

    No mention of the threat of Cream Pigs?

  4. solarfarmmom Says:

    Pop-I’ve been keeping them at bay with periodic hits of pure cream. Fortunately, we’re getting plenty right now!

  5. Katie @ Kitchen Stewardship Says:

    Wow, I haven’t learned so much absolutely new information in a while. I love it! Thanks for sharing the academic and nutrition side, with photos. I was wondering why the cream seemed thinner in the summer when the cows got out to pasture; I expected it to be thicker because of reading about the fast-growing spring grass and how healthy the butter in May/June is. I assumed that would mean thicker and more abundant cream, but it makes sense that there’s more cream in winter. Mmmm, fresh yellow butter…Now I need a roll!

  6. jammer Says:

    I must take a contrary position on the amount of cream in summer. I live next to a dairy where I buy all my milk. We talk a lot and his fat content went up quite a bit for a while this summer. Now, the reasons might be interesting. Is it because they were hotter and partially dehydrated when they came in to get milked? I don’t know.

    I just know what I saw and how much cream I was getting in my milk jars. Mmmm. If you truly want to be decadent, take wheaties or corn flakes, put peanut butter on it, then pour on the cream. I’ve only done it twice because I like to be able to look myself in the mirror. ;) But it sure is good.

  7. solarfarmmom Says:

    I’m not trying to make any rules here. Cream content can change for many reasons, known and not. A ketotic cow, for example, will give more cream.

    Now, I will be contrary: why would you waste fabulous cream on corn flakes or wheaties!! Yikes! We consume about 2 quarts of cream in coffee alone each week (that’s just hubby & me) and we are in no way fat. It’s the wheaties & corn flakes making people that way!

    Thanks for commenting!

  8. Matt Says:

    so, if our milk’s fat content is about 3.5%, and I let a gallon sit for 12+ hours, and then pull the cream off the top, about how heavy is that cream? it seems to be more like half-and-half to me, and I’m still not sure what I should classify it as when using it in recipes.

    I thought I heard somewhere that cream can’t naturally rise to more than 20%

  9. solarfarmmom Says:

    Hi Matt. Thanks for visiting. If you are skimming ALL the cream off that jar after just 12 hours, yes, it will be thinner, more like half & half. I find that a 24 hour chilled rise gets me a nice, thick layer of heavy cream on the top. That’s skimming just the first layer off the top of the jar and leaving most of the cream there. It almost comes out in a big chunk. That is what was traditionally called “heavy cream”. It has the highest fat content (the mostly tightly packed cream globules). The cream remaining in the jar will be lighter but not necessarily half and half.

    So the cream thickness is more a matter of where in the layer of cream you are skimming coupled with the amount of time it has risen.

    I would classify the cream you are skimming after 12 hours as “light cream”.

    As for the 20% rule to which you refer, cream is generally measured by weight. That’s the 3.5% number you mention…..3.5% milk fat by volume. So I’m not sure what 20% means. Perhaps you mean that it is not possible to get cream that is higher than 20% milk fat. While I’ve never measured (I’ve no way to do it), I suspect that number is based on skimming ALL the cream off the milk, not just the heaviest. If you want truly heavy cream, take just that thick layer I mention. You’ll know what I mean when you see it.

    Let me know if this was helpful, Matt.

  10. Harl Delos Says:

    If milk is 3.5% butterfat, that would be 4.5 ounces per gallon. It that was separated into absolutely skim milk and 20% butterfat cream, you’d end up with 22.5 ounces of cream – about 1/6 cream, which seems like a LOT of cream.

    Virtually all dairy breeds produce more than 3.5% butterfat. That’s a government standard put in place at the behest of dairies that wanted to be sure to be able to sell all their milk as whole milk, back in the days when most milk was sold that way. (Skim has been around a long time, but 2% was introduced about 1960 and 1% even more recently.)

    If you want heavier cream, simply run it through a Delaval cream separator more than once. “Heavy” cream is actually light-weight cream since it floats on top, while “light cream” contains more water and protein and sinks lower.

  11. solarfarmmom Says:

    Thanks, Harl. Informative comment, as usual.

    People do not realize that commercially produced milk is “taken apart” then put back together to match the government standards. The government is always looking out for our best interests too!

    I’ll stick with hand skimming myself. It’s hard to lick the cream off your fingers when all the cream is in the separator. And I wash enough dishes as it is.

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