Many people think of “spoiling” when milk changes over time. But the natural evolution of dairy is a beautiful process. In fact, traditional sour cream is essentially milk’s own solids separating and fermenting over time. We invite you to return to the way natural dairy is done. We’re a Canadian sheep dairy farm, and we love sharing how real milk transforms on its own. Join us as we delve into dairy solids, cream, and the history of milk, guided by real research and historical context.
Dairy Solids and Cream: How Milk Separates Naturally
Milk is mostly water with a portion of dairy solids (fat, protein, sugar, and minerals) in it. When you leave natural fresh milk undisturbed, something magical happens. The fat and other light components start rising upward due to gravity. Over several hours, these butterfat globules float to the surface to form a rich layer known as cream. This top layer is essentially concentrated milk fat (and some protein), while below it lies the remaining skim milk (mostly water, lactose, and proteins). This simple separation is how people obtained cream for centuries before modern equipment.
What are dairy solids? They are everything in milk that isn’t water – the fats, proteins, lactose (milk sugar), and minerals. These solids come directly from the animal’s milk. As milk sits, milk solids separate into visible layers. The rising cream is full of fat (which is why cream has a thick, yellowish look). Meanwhile, heavier water-based components stay below. Early dairymen and women would literally skim off the cream by hand once it rose to the top. This is the origin of terms like “skim milk” – the milk left after skimming off the cream.
From Cream to Sour Cream: Milk’s Natural Fermentation
Over time, if fresh whole milk sits a bit longer, nature continues the process. Milk contains beneficial bacteria that start to ferment the lactose (sugars) into lactic acid. As the hours pass (especially at room temperature), the milk begins to sour and thicken. The cream on top also ferments and thickens along with it. Traditionally, people used this process to create sour cream and similar cultured dairy. They would skim off the naturally soured cream from the top of a batch of clabbered (naturally curdled) milk. In other words, sour cream is literally “soured” cream – cream that has been thickened and preserved by natural fermentation.
Traditionally, making sour cream was very simple. You just let the cream (fresh cream skimmed from milk) sit out and ferment. The natural lactic acid bacteria in dairy would do the rest, thickening the cream and turning it pleasantly tart. This was essentially a preservation method – the increased acidity keeps the cream from spoiling further. The end result is a rich, tangy sour cream that our ancestors enjoyed with no artificial additives. In some cultures, similar fermented cream is called crème fraîche or smetana, but the principle is the same.
The great thing is that you can still do this today. If you have non-homogenized whole milk, you can skim the cream and let it naturally sour to make your own sheep sour cream or cow’s sour cream. After reading this, you should be able to try making sour cream for your pierogies or a dollop in coffee. So don’t toss that old whole milk! The dairy world is full of opportunities hidden in plain sight.
Factors That Affect Cream: Breed, Season, and Feed
Not all milk produces the same amount of cream. The quantity and richness of cream (the sheep milk cream or cow cream that rises) can vary widely. It depends on the source of the milk – the animal species and breed – as well as the season, the animal’s diet, and even the weather. For example, ewes’ milk (milk from female sheep) is naturally very high in fat and protein. Sheep’s milk often contains about 6–10% fat, roughly double the fat content of cow’s milk (which is around 3–4%). Because of this, sheep milk yields a very thick, rich cream (if you can get it to separate, as we’ll discuss later). Lambs thrive on this rich lamb milk, and humans appreciate its indulgent quality too.
Different breeds of dairy animals also have different cream levels. A Jersey cow produces milk with high butterfat (creating a thick cream line). At the same time, a Holstein cow yields a larger volume but with less fat. Goat’s milk and sheep’s milk tend to have smaller fat globules, which influences how the cream behaves (more on that soon). Beyond genetics, the season and feed play a role. Cows and sheep grazing on lush spring pasture may produce milk with slightly different fats (like more omega-3 fatty acids and beta-carotene from green grass).
In cooler seasons, or late in lactation, milk can actually contain higher overall fat and protein solids. Farmers long observed that milk in winter (when cows ate more hay and less fresh grass) often had a bit more fat and “solids-not-fat” content than summer milk. Environmental stressors matter too. For instance, very hot weather can reduce milk fat yield as the animals eat less and experience heat stress.
How Diet Shapes Milk Quality
Diet is crucial. Rich, balanced diets yield more nutritious milk. An animal on high-energy feed with good forage will give milk with robust fat content. On the other hand, poor nutrition or stressful conditions can thin out the milk. We see this even on our farm. Our ewes on organic pasture and high-quality hay produce wonderfully rich organic sheep milk. The better the feed and care, the more cream and solids naturally end up in the milk. Mother Nature has a way of adjusting the milk composition based on conditions and needs.
The takeaway: the amount of cream that forms on your milk isn’t fixed. It can differ by animal (cow vs. goat vs. sheep), by time of year, and by farming practices. Sheep dairy farmers know this well; the spring flush of milk when lambs are born might have a different character than midsummer milk. Real milk is a dynamic, living product – and its cream layer is like a snapshot of the animal’s health and environment at that moment.
Dairy History: From Hand Skimming to High-Tech Processing
Dairy practices have evolved dramatically over the centuries. Let’s take a quick tour through milk history and see how we went from simple methods to today’s high-tech processes.
Traditional Milk Processing (Pre-1800s)
For thousands of years, people consumed milk and dairy in a very natural way. After domesticating cows, sheep, and goats around 9000–7000 BC, early farmers learned to utilize milk quickly or preserve it. Without refrigeration, fresh milk would sour within a day. Ancient cultures discovered that letting milk sit would separate cream, which they could use for butter, and let the milk sour into clabber or yogurt-like products. This wasn’t considered spoilage – it was the normal way to get dairy. In many households up through the 19th century, milk was set in shallow pans or buckets. By the next morning, a layer of cream formed on top which was skimmed off for making butter or cream products.
The skimmed milk might be used as lower-fat milk or further fermented into cheese or sour drinks. This gravity separation (also called “sedimentation by gravity”) was the only method available, and it’s literally as old as Roman times. In fact, the Romans even designed simple spouted bowls to help pour off cream from milk. However, these methods were slow and often the milk would begin to turn sour before all the cream could be collected.
The Invention of the Cream Separator (Late 19th Century)
A major breakthrough in dairy came in the late 1800s with the invention of the centrifugal cream separator. In 1878, a young Swedish engineer named Gustaf de Laval patented the first practical centrifugal cream separator. His machine spun fresh milk at high speed, using centrifugal force to separate the lighter cream from the heavier skim milk much faster than gravity. By 1883, De Laval had formed a company to manufacture these separators on a large scale.
The impact was huge – farmers could now separate cream in minutes rather than waiting hours, and they could extract more cream before milk soured. By the turn of the 20th century, hand-cranked cream separators became a common sight on dairy farms across Europe and North America. This sparked a dairy revolution, as nearly all creameries started using mechanical separators to increase efficiency. The cream separator not only saved time, it also increased yields (no fat left behind in the skimmed milk). It was said to save dairy farmers a few dollars per cow per year – a significant benefit back then.
The introduction of the cream separator also influenced what dairy products were made. With easy access to large quantities of cream, butter production boomed in the late 19th and early 20th century. Meanwhile, the leftover skim milk (fat-free or low-fat milk) became more readily available, which later led to the idea of selling skim milk and using it in other products instead of wasting it.
Pasteurization and Safety (Late 1800s – Early 1900s)
Around the same era, public health brought about pasteurization. Milk can harbor harmful bacteria if not handled properly, so heating milk to kill microbes became important. Louis Pasteur’s principles (first used for wine) were applied to milk by the late 1800s. By the early 1900s, many cities began to require pasteurized milk for public sale. Pasteurization typically means heating milk to about 72°C for 15 seconds (or an equivalent process) to eliminate pathogens. This step greatly improved milk safety and shelf life. However, it had a side effect: some nutrients like vitamins A and D, and enzymes in milk were reduced by the heat. Later on, dairies began fortifying milk by adding vitamins A and D back into processed milk to compensate. So if you see “vitamin A&D added” on a milk jug, that’s why – pasteurization, while crucial, prompted the need to fortify the milk afterward.
Homogenization and the End of the Cream Line (20th Century)
If you’ve only ever bought homogenized milk, you might not even know that cream naturally rises. Homogenization is a mechanical process that became widespread by the mid-1900s. It was invented by a Frenchman, Auguste Gaulin, who first demonstrated it in 1900. Homogenization works by forcefully blasting milk through tiny orifices at high pressure, which shatters the fat globules into much smaller ones. The result is that the fat stays evenly suspended in the milk, and no cream layer will form. Homogenized milk was introduced in the 1920s–1930s and quickly became popular with consumers for its consistent texture.
By the 1950s and 60s, homogenized milk had largely taken over in the market (for example, the first homogenized milk was sold in Ontario, Canada, in 1927, and within a few decades it was the norm). This was convenient – no need to shake the bottle or scoop out cream – but it was also the end of seeing the lovely cream-top in milk bottles. Some argue it also changed the mouthfeel and taste of milk (cream-top milk has a distinctive silky taste). In any case, by homogenizing, companies ensured every sip of milk had the same fat content. It also extended shelf life slightly and prevented the “blue skim” appearance that non-homogenized skim milk has.
From a traditionalist standpoint, homogenization was one more step away from the natural state of milk. Today, a few dairies sell “creamline” milk (non-homogenized) for those who crave the old-fashioned experience, but most milk in stores is homogenized.
Standardization and Modern “Designer” Milk (Late 20th – 21st Century)
As dairy technology advanced, producers didn’t stop at separating cream. Milk began to be treated as a collection of parts that could be recombined in various ways. By the mid to late 20th century, dairies routinely standardized milk to specific fat percentages – 2% milk, 1% milk, skim (0%). How do they do this? They use the separator to remove cream, then they can add a calculated amount of cream back into skim milk to reach exactly the desired fat percentage. For example, to make 2% milk, they blend back enough cream into the skim to get 2% fat content. This allowed consistent products and labeling of milk fat for consumers.
In recent years, we’ve even seen “ultra-filtered” or high-protein milk on the market. Producers take milk and run it through special filters to separate out water, lactose, and concentrate the proteins. Then they recombine components to create milk with more protein, less sugar, etc. Essentially, milk is being deconstructed and redesigned. A company might remove some lactose and water, then add extra milk protein concentrate to boost protein content – all to appeal to modern health trends.
How Modern Milk Is Modified and Fortified
One example is ultrafiltered milk that has 50% more protein and 50% less sugar than regular milk. The industry can also add dry milk powder or milk protein isolates to fortify products. In fact, many low-fat dairy products are enhanced by adding milk solids back to improve taste and body. It’s not uncommon for a 0% fat milk to contain added nonfat milk powder, so it isn’t just “chalky water.” As one source notes, modified skim milks have added milk solids to reach at least 10% total solids – achieved by mixing in skim milk powder or evaporated milk. This makes skim milk thicker and whiter, mimicking whole milk’s mouthfeel (sometimes sold as “skim deluxe” or “creamier skim”).
All these changes mean that today’s commercial milk is quite different from the raw milk our great-grandparents knew. We live in a world filled with highly processed or “enhanced” dairy products. From shelf-stable milk boxes (thanks to ultra-high-temperature pasteurization) to protein-fortified “super milk”, the spectrum is vast. While these innovations have benefits (like longer shelf life or extra nutrients), they also move us away from milk’s natural form. We believe there’s value in understanding milk’s journey and appreciating it in a more traditional, wholesome state.
What Is a Cream Separator and Why Use One?
Let’s talk a bit more about the cream separator itself. As mentioned, a separator is a device (originally hand-cranked, now often electric) that spins milk to separate cream. Inside the machine, the heavier skim milk is flung outward, and the lighter cream collects inward, effectively sorting them into two outputs. In the late 1800s, this was a recent invention that changed dairying almost overnight. It was adopted not for any “health” reason, but for practical and economic benefits – it saved time and increased butter production.
In modern times, why do producers use separators?
There are a few reasons:
- Standardizing Fat Content: As discussed, dairies separate cream to create milk with specific fat percentages. This isn’t really about health in the nutritional sense. It’s about meeting consumer demand for options like low-fat milk and being able to label the milk as 0%, 1%, 2%, etc. If you think about it, cow’s milk straight from the animal might be ~3.8% fat on average. By using a separator, companies can reduce that to exactly 2.0% and legally call it “2% milk”. The separator thus allows them to “write down the percentage of milk fat in the milk,” so to speak, and have consistency.
- Creating Cream and Skim as Separate Products: A separator lets a dairy produce heavy cream, light cream, butter, etc., from the same batch of milk. It also gives skim milk as a by-product which can be sold or used in other products. In the old days, surplus skim was fed to pigs or used in cooking. Today it’s often dried into powder or added to other foods.
- Efficiency and Shelf Life: Removing cream can help the remaining skim milk last a bit longer (since fats can carry flavors or go rancid faster). And as mentioned, it’s much faster than gravity separation.
The Problem with Reconstructed “Super Milk”
However, not all producers use separation in an “all-natural” way. Some large-scale producers have taken to extreme separation and recombination. They might take whole milk apart (into cream, skim, proteins, etc.) and then recombine them in novel ways. For instance, to market a “healthy high-protein milk”, a company can remove most of the cream (fat) to make it low-fat, then add dry milk powder or milk protein concentrate to boost the protein above normal levels. They might also add vitamins, fiber, or other additives to appeal to health trends. The result is sold as a super milk with extra protein or calcium, but it’s essentially a manufactured product.
It’s ironic that they start with whole milk – nature’s perfectly balanced food – strip it, and then mix things back in, claiming it’s healthier. In reality, whole milk already contains those nutrients in natural proportions.
Why We Believe in Keeping Milk Whole and Natural
Another example: to make some “ultra-skim” milks taste better, companies will add lactose or nonfat solids. So it isn’t like bluish water. This is done purely for market preference (so consumers enjoy the taste/texture and see a white color). It’s not added for your health, but so that they can sell you zero-fat milk that still has some body to it. We call such products “modified milk”. Just check the ingredient list on certain milks, and you’ll see things like milk powder or concentrate listed.
From a health perspective, opinions vary on whether it’s better to drink milk with fat or without. For decades, people were told to choose skim for health. But modern research has redeemed milk fat to a large degree, showing that dairy fat can be beneficial and that whole milk might be associated with better health outcomes than sugary nonfat alternatives. In any event, our philosophy is to keep milk as natural as possible. We let the consumer decide how much to consume, rather than heavily engineering the milk. We believe that when we produce quality milk from healthy animals, the whole milk is a balanced food on its own.
Sheep Milk and Natural Homogenization: Our Separator in Action
Now, let’s bring the focus to our specialty: sheep dairy. Sheep milk is an amazing product – it’s incredibly rich in solids (both fat and protein). However, if you pour a fresh bottle of sheep’s milk cream (i.e. whole sheep milk), you might notice something surprising: there’s little or no cream line visible. This is because sheep milk (like goat milk) is naturally homogenized. That means the fat globules in sheep milk are much smaller than those in cow milk, and they remain suspended evenly in the milk. The cream doesn’t rise easily on its own. In fact, without mechanical help, you might not be able to separate a meaningful amount of cream from sheep milk at all. The milk will likely just ferment uniformly (which is fine for making cheese or yogurt, but you won’t get a layer of cream to skim).
What does “naturally homogenized” mean? It means the milk fat is emulsified in tiny droplets naturally, so the milk stays homogeneous (uniform). In cow’s milk, fat globules are larger and will join together and float up over time. But in sheep milk, the fat globule diameter is so small that it resists separation. One source points out that sheep milk’s fat globules make it creamy and homogeneous by nature. This trait also makes sheep milk easier to digest for some people, since the fat is in smaller particles.
How We Make Naturally Rich Sheep’s Milk Cream
On our farm, we do use a cream separator for our sheep milk – but for a different reason than many cow dairies. We’re not removing the cream to make the milk “skim”; we’re using it to actually obtain cream and make high-quality sheep dairy products. Since the cream won’t rise by gravity, a gentle mechanical separation is needed to get sheep cream for things like butter, sheep sour cream, and sheep milk ice cream. By spinning out some cream, we can create these products while leaving behind a leaner milk that we often turn into cheese.
Importantly, the cream we collect from our sheep milk is full of natural nutrients and fat – nothing is taken away from it. We don’t dilute it or standardize it to a lower percentage. Our sheep cream is as rich as it comes from the ewe, just concentrated. The same goes for our sour cream made from sheep milk. It’s thick, nourishing, and contains all the original vitamins, minerals, and healthy fats that our ewes’ milk is known for. We merely add cultures (or let it ferment) to become sour cream, without any need to fortify, because nature’s recipe is already perfect.
Dairy, made traditionally
In essence, we use modern equipment (the separator) to honor an old-fashioned quality – the wholesomeness of whole milk. It allows us to craft traditional-style dairy products (like cream or sour cream for your baking and cooking) from sheep milk, which otherwise you couldn’t easily skim. And because sheep’s milk is so nutritious (with up to twice the protein and fat of cow’s milk), our cream and sour cream pack a serious nutrient punch. They are rich in fat-soluble vitamins, conjugated linoleic acid (CLA), and medium-chain fatty acids that are more easily utilized by the body. Nothing has been “stolen” or replaced in our dairy – no dry milk additives, no artificial proteins. It’s the real deal, just separated and cultured in a controlled way for your enjoyment.
Embracing Real Dairy Traditions
We hope this journey through milk solids natural timeline and dairy history has given you a deeper understanding of real dairy. In a world of artificial and over-processed products, there’s something comforting about knowing how to make simple, authentic dairy foods at home. Whether it’s letting a jar of whole milk sit to gather cream on top, or fermenting that cream into tangy sour cream, these are skills and experiences that connect us to generations past.
At Secret Lands Farm, we are proud to carry on these traditions with our own modern, organic twist. We’re a Canadian sheep dairy that believes in transparency and quality from farm to table. Our practices – from letting our lambs drink their fill of rich ewe’s milk, to using gentle techniques to craft dairy products – all center on respecting what milk naturally is. We like to say that milk itself contains the blueprint for so many wonderful foods. You don’t need to overly engineer it; you just need to guide it along its natural path.
Rediscovering the Beauty of Real Dairy at Home
If you have whole milk in your fridge (especially non-homogenized milk), now you know you don’t have to rush to finish it or throw it away when it sours slightly. That sour milk can become clabber, which in turn gives you homemade cream cheese or baking leaven, and its top cream becomes homemade sour cream. With a bit of patience, you can skim cream for your coffee or whip it into butter. The possibilities in the dairy world are endless once you understand the basics.
We’re passionate about helping you discover the beauty of real dairy – from the farm history to the practical kitchen know-how. If you have any questions or want to learn more, just let us know. We’d be more than happy to delve into new topics in future articles. Discover the beauty of this world with Secret Lands Farm, and indulge in the creamy goodness that nature provides!
Sources
Why is Some Skim Milk Thicker? – Straight Dope
https://boards.straightdope.com/t/why-is-some-skim-milk-thicker/958361
How the Separator Sparked a Dairy Revolution – Tetra Pak
https://www.tetrapak.com/en-us/insights/cases-articles/how-the-separator-sparked-a-dairy-revolution
How To Make Sour Cream (4 Different Ways + Video) – Traditional Cooking School
https://traditionalcookingschool.com/food-preparation/how-to-make-sour-cream-4-different-ways-video/
Sour Cream Making Instructions – Bacillus Bulgaricus
https://bacillusbulgaricus.com/sour-cream-making-instructions/
Cow Milk vs. Goat Milk vs. Sheep Milk – Which Is Healthier? – Hidden Springs Creamery
https://www.hiddenspringscreamery.com/blogs/news/cow-milk-vs-goat-milk-vs-sheep-milk-which-is-healthier
The Effect of Different Seasons on the Milk Quality – Prime Scholars
https://www.primescholars.com/articles/the-effect-of-different-seasons-on-the-milk-quality.pdf
Optimizing Dairy Cow Nutrition to Manage Milk Fat Reduction – Novus International
https://www.novusint.com/Blog/optimizing-dairy-cow-nutrition-to-manage-milk-fat-reduction
Milk – Wikipedia
https://en.wikipedia.org/wiki/Milk
High Protein Milk: It’s Not Just Milk with Added Protein Powder – McGill OSS
https://www.mcgill.ca/oss/article/nutrition-health-you-asked/high-protein-milk-its-not-just-milk-added-protein-powder
Why Sheep’s Milk – Velvet Cloud
https://velvetcloud.ie/pages/why-sheeps-milk