So what’s winter butter? That’s a good question, and the answer is pretty much what you’d think: butter that’s produced in the wintertime. However it isn’t just cold weather that effects the texture of butter, it’s the winter diet of the dairy cows who give the milk. On a traditional farms, cows graze in the fields in the summer and are fed hay and/or silage in the winter when pickings in fields are scarce. Cows fed on these lean winter diets give milk that’s compositionally different from that given in warmer months.
What’s the difference? It’s said that winter butter isn’t as rich as summer butter, but that’s not necessarily so. What is true is that the fatty acids in the cream component of winter milk are different. That is, they tend toward more saturated fats, and as you may recall from past posts on fats, the more saturated a fat gets, the firmer it is at room temperature. This is because saturated fat molecules are more uniform and form crystals more readily than unsaturated fats. More fat crystals give the butter a higher melting point, making it harder.
It also makes it better for pastry, since the higher melt point means the butter layers in the dough hold up longer in the oven, giving the dough layers more time to set up in the heat. The end result: flakier pastry.
Sounds great, where do I get it? Well, if you don’t live near a traditional dairy farm in a temperate climate, it’s tough if not impossible. Industrialized dairies feed their cows a uniform diet year-round. This way, they create a more consistent product. Modern dairies also “fractionate” their butter fat, separating it out by centrifuge and mixing it in proportions that make their butter the same year-round. This makes a lot of sense from a business standpoint, since consumers always like consistency. However it hangs a lot of us pastry-making types out to dry, as it were.