The Chemistry of the Churn
- Anjali Carl
- 11 minutes ago
- 3 min read
If you ever look at standard American supermarket butter and compare it to French butter, you instantly notice a difference. The cultured French butter is bright yellow and bendy when cold, and it has a tangy smell. The difference between the two types of butter comes down to emulsions, fat crystals and fermentation.
Butter is, at its core, a water-in-oil emulsion, which is when water droplets are trapped inside a network of fats. Depending on where the butter is made, law dictates how much water is allowed to stay in that network. In American butter, the USDA requires a minimum of 80% milk fat and the other 20% can be water. The European Union, on the other hand, requires a minimum of 82% milk fat.
While 2% sounds tiny, it can shift the cooking chemistry pretty dramatically. Because American butter has more water, it creates more steam when it gets hot in the oven. This causes the tiny air pockets in dough to expand, helping cakes rise and cookies spread out. Contrast this with French butter which has a lower water content so there is less liquid to hydrate the flour’s protein. Less water means less gluten development leading to a more tender texture and flakier pastries.
Another big difference between the two types of butter is cultures. American butter is typically sweet cream butter. This is fresh cream that’s pasteurized, chilled, and then immediately spun in huge churns resulting in a flavor that’s mild, sweet and similar to milk. French butter is cultured butter where Lactococcus lactis bacteria are added to warm cream and allowed to ferment for 16-20 hours before churning. As the bacteria consume lactose, they produce two compounds: lactic acid and diacetyl. Lactic acid gives the butter a tanginess and the diacetyl is an aroma compound that gives butter its classic buttery smell.
Trying to roll out cold American butter for pies or croissants is tough because it can crack into chunks, whereas French butter is more malleable. This feature is due to the cooling and churning speed. French creameries usually churn cream slower and very precisely control the temperature to influence how the fat crystals pack together. The goal is to maximize the amount of liquid trapped inside the fat crystal network. This structure allows the butter to be rolled paper-thin without snapping.
Each butter does better in specific situations. Use French butter for laminated pastries like croissants and for shortbread. The butter’s plasticity prevents the fat layers from breaking down during rolling and the low water content keeps the pastry very tender. American butter is great for soft cookies and high-rise cakes. The extra water helps with lift and to help cookies spread perfectly on the baking sheet.
Choosing the right butter is all about letting food chemistry do the work for you.
Anjali Carl is a junior at Cedar Park High School in Cedar Park, Texas. They have been excited about food science since making ice cream in a third-grade science class, and now enjoys baking and recipe development. Through their Girl Scout Gold Award project, they created two cookbooks focused on reducing food waste for food pantries and college students. They plan to study food science and eventually become an ice cream chemist.
Are you working on a new food or beverage product? Interested in working with me and my team to get started?
Click on the button below to get in touch and set up a meeting today!
