In the Netherlands, sour cream and creme fraîche often share a shelf in the supermarket. They’re packaged in very similar packaging and even look and taste alike to some extent. But recipes can be very specific about using just one and not the other. Looking for something to top your baked potatoes or nachos, you’ll likely find sour cream on top of it. Recipes for a creamy sauce on the other hand might call for creme fraîche to be whisked through.
It can be confusing to keep them apart, let alone not mix them up with other similar dairy products (what about crema?). It all becomes a little easier once you know how they’re made and what they’re made of. We’re all about giving you the tools to help you understand your food, helping you to figure out how things work!
Both sour cream and creme fraîche are cultured creams. They both start out as cream, made from cow’s milk, which is then fermented by microorganisms. That fermentation process turns the cream sour and changes the flavor and texture of the cream.
Cream is made from milk which, by itself, is quite a complex product (see infographic below). Aside from water milk contains about 4% of fat (exact content depends on the cow and its environment), some sugars (lactose), and proteins. When you’re making cream, you’re trying to separate that fat fraction from the majority of the water. You want to end up with something that has at least 20% fat, up to more than twice that content.
Traditionally, you would have made cream by leaving your milk to stand in a container. The density of fat is lower than that of water. As a result, it will rise up to the top of the milk over time (through a process that’s the opposite of sedimentation). The top layer will be rich in fat (though still contains quite some water as well as some proteins and sugars) and would have been skimmed off. Just what fat-% your cream has depends on how you separate the cream, how long you’ve waited, etc.
Nowadays, instead of waiting several hours, manufacturers speed up the process by using centrifuges. They literally swirl the fat and water phase apart. Using this process, they can control the percentage of fat in the final cream very well to create a consistent flow of cream. Depending on the settings, they can make creams with a fat content anywhere between about 20-50%.
Back in the day, before refrigeration and pasteurization existed, people would leave their cream to sit at room temperature. Microorganisms naturally present in the milk, as well as those from the surroundings, would find a good home in the cream. They’d thrive and grow, turning the cream sour, making cultured cream.
These sour, cultured creams developed throughout the world in dairy centric communities. All of them would be slightly different in their texture and flavor. Most likely, even within the same household, the creams would turn out slightly different every time. Since the microorganisms in the cream that cause the culturing are living organisms, the process would be affected by factors such as temperature, quality of the cream, time, etc.
Nowadays, by carefully controlling the process cultured creams, can be made very consistently, time and time again. Manufacturers tightly control the temperature, duration, they even add specific cultures of microorganisms to ensure consistency.
There’s more than just sour cream and creme fraîche
Sour cream and creme fraîche are just two types of cultured cream. Creme fraîche has its roots in France. Other cultured creams might come from different origins. For instance, crema (Spanish for cream) can commonly be found in Central America and smetana has Russian origins.
What happens when culturing cream
So what really happens once those microorganisms get to work in the cream? For one thing, the consistency and flavor of the cream change drastically. Whereas fresh cream is quite neutral in pH (not that acidic, not alkaline) and quite liquid (very easy to pour), cultured cream is noticeably thicker and more sour. It’s bacteria that cause these changes.
The two most commonly added strains of bacteria are Leuconostoc and Lactococcus. Both are lactic acid bacteria and use a process called lactic acid fermentation to grow and thrive in the cream during culturing. They use the lactose, naturally present in the cream, as an energy source. In doing so they convert it into various other molecules.
Since each bacteria might convert chemicals in a slightly different way, manufacturers tend to use a mix of bacteria to get the desired properties. A lot of research is put into these blends to ensure the product not only tastes good but is also made within a reasonable timeframe.
It turns sour
An important characteristic of lactic acid bacteria is that during fermentation they produce lactic acid. As the name says, this is an acid so it will turn the cream sour, and bring the pH-value down.
Lactic acid bacteria don’t mind the acidic environment, whereas a lot of other (potentially harmful) bacteria do, helping to extend the shelf life of the cream!
Flavor components are formed
Converting lactose into lactic acid isn’t the only chemical reaction that occurs. Microorganisms are complex and thus several other components will be formed. Some of these contribute to the unique flavor of cultured creams. The final flavor is made up of a lot of different molecules, all contributing to the flavor. However, one of the main flavor components in cultured cream is diacetyl, which is known for its buttery flavor.
The cream thickens
Aside from these flavor changes, the cream also thickens during the culturing process. Again, there are various mechanisms at play. First of all, some of these added bacteria can form large molecules called exopolysaccharides. These long, complex molecules hold onto moisture and form structures with the proteins in the cream. These two mechanisms cause thickening.
Thickening is also aided by the souring of the cream. Cream contains proteins, caseins. These caseins are what make it possible to convert milk into cheese. When the cream turns sour, these casein molecules will reorganize themselves. This causes the formation of a more ordered structure, thickening the cream. Cream contains a lot more fat than milk (and less proteins), so the final product is very different than a cheese (e.g. paneer) or yogurt.
Modern day manufacturing: additives
You can make cultured cream with just cream and the right microorganisms. However, you might notice the ingredient list on your cultured cream to be a little longer. Most of these additional ingredients (additives) are added to thicken the cream. The ‘natural’ thickness can be quite delicate, so adding thickening agents helps to stabilize it.
Common examples of thickeners are carrageenans, a group of large polysaccharides that come from seaweed. Also, you might find guar gum or some sort of cellulose. Not coincidentally, you can also find these additives in a lot of ice creams, where they’re also added to improve texture.
Another way to thicken up cultured creams is by reducing the amount of water. It is why sour creams with a high-fat content tend to be thicker than those with a lower fat content. Also, it is also why manufacturers might add dried milk to the cream.
To help the coagulation of the casein molecules, some manufacturers might add rennet. This is an enzyme commonly used when making cheese and also helps to thicken.
Sour cream vs creme fraîche
So, now that we know what cultured creams are and how they’re made, let’s have a look at sour cream & creme fraîche specifically. In Europe and the US at least these two tend to be most common and well defined. In the US sour cream has to contain 18% fat and only a select number of additives (mostly those mentioned above) may be added for it still to be called sour cream. The US does not have particular legislation on what a creme fraîche entails.
In Europe on the other hand the definitions for sour cream and creme fraîche aren’t as exact, they might also differ between countries. Generally, countries have legislation on the minimum fat content for a product to be called cream, however, there are a lot of differences between countries. For instance, in France, cream should contain at least 30% fat, anything below should be a light cream). In the Netherlands on the other hand ‘cream’ should contain at least 10% fat and ‘whipping cream’ should contain at least 30%. All of this to show that there are a lot of differences. That said, there are some general differences that hold up in a lot (but not all) cases when comparing sour cream and creme fraîche.
Generally speaking, sour cream contains less fat than creme fraîche. A common distinction seems to be that creme fraîche contains at least 30% fat and sour cream 20% (or less). However, big differences between countries exist.
Another commonly observed difference is the sourness of the two product. Generally, sour cream is more sour, with a common pH-value (a measure for acidity, lower is more acidic) of 4.5. Creme fraiche on the other hand might have a pH closer to 6, thus clearly less sour.
A note on French creme fraîche
Keep in mind that creme fraîche literally means ‘fresh cream’. As such, ‘fresh cream’ (one that has not been cultured and thickened) is called ‘creme fraîche’! When looking for the cultured version of fresh cream in France you should be looking for the ‘epaisse’ version, which means it’s been thickened!
When to use sour cream vs creme fraîche
So definitions are clearly not as clear-cut as you might be hoping for. If you’re in doubt, you may want to refer to other indicators on your label as to what your product is. Look at the fat content and see if there’s a mention about the cream being cultured. That said, assuming that sour cream contains less fat and creme fraîche contains significantly more, that does make them suitable for quite different purposes.
Because sour cream contains less fat and thus relatively more proteins on a weight-basis, it will curdle or split more easily when you use it in a hot application. The heat and the acidity will cause the casein molecules to curdle, much as what you want to happen when making cheese! Creme fraîche contains a lot more fat and thus relatively less protein. It is why it does tend to be stable in hot applications and not cause significant shifting!
Aside from shifting and curdling, there’s also a difference in flavor. Of course, the difference in acidity will result in different eating experiences. But so does the fat content. A fatty creme fraîche almost acts as a whipped cream, being both thick and silky.
So try them out, see how the ones you have access to differ and take the chance to serve both during a dinner party while explaining just exactly how these cultured creams are made!
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