As Pierre explained it, winter butter is made with the milk cows produce when the majority of their feed is hay rather than fresh grass. Winter butter is pale, almost white (not golden like spring and summer butter), dry and excellent for puff pastry. So excellent, in fact, that Pierre said they stockpile the butter in their freezers so they’ll have it on hand in the ‘off’ seasons.
I’m sure you’ve guessed by now, but you can only get winter butter from buttermakers whose milk comes from grass-fed cows. In other words, don’t expect recognizably different winter butter from your supermarket brand, since most commercial buttermakers must strive for year-round consistency.
But dryness isn’t the only factor that’s important when you’re considering butter for a pastry in which everything depends on it. You’ve got to consider fat and acid, too.
Butter is composed of fat, a negligible amount of milk solids and water and, to state the obvious – again – the more fat, the richer the butter. The amount of fat changes how the butter feels in our mouths and how it works in our doughs. How it tastes has to do with the quality of the milk and the buttermakers’ finesse.
By law, in America every butter (except salt butter) must contain a minimum of 80% butterfat, while in France that minimum is 82%. While a 2% difference might not sound like much, just remember, whatever is not fat, is water. Interestingly, many of the best butters in France (butters like EchirÃ©, which are AOC, Appellation d’Origine ControlÃ©e) contain 84 – 86% butterfat, as does the American butter from Vermont Butter & Cheese Company.
The acid in butter is less talked about than the fat, but it’s no less important in terms of taste and the way it works with dough. In fact, a butter rich in lactic acids will have a very different taste from ‘regular’ butter, a taste which comes from ‘culturing’ or fermenting the cream before it is churned into butter. Think crÃ¨me fraiche and you’ll have an idea of the kind of tang that cultured butter has.
Culturing butter is slow and therefore expensive. The cream is allowed to ferment (cultures, like those used to make yogurt, are added to the cream) for hours before it is turned into butter. Churning this cream (which really is like crÃ¨me fraiche) produces a butter with real flavor, one that lasts in a way that uncultured butter doesn’t, and a level of lactic acid that – and this I also learned from Pierre Herme – improves the way some butter/laminate doughs, like those for croissants and kouing-amanns, as well as other yeasted doughs, develop. And, of course, whatever you bake with them will be richer and have more flavor. Butters that are cultured, and there aren’t very many of them in the States, will say ‘cultured’ on the label. (Again, there’s Vermont Butter & Cheese Company butter and butter from the Straus Family Creamery in California.)
If you want to do a little taste test, try making my Bubble-Top Brioches (pictured, just out of the oven, at the top of this post), which were in this month’s edition of The Baker in Bon Appetit. You can read the brioche story here (it’s always fun when I can get my husband, Marie Antoinette and butter into one article), find the recipe here, and get a bonus recipe for the Brioche tarte-au-sucre, shown above in a photo by Aya Brackett taken for Bon Appetit.