What do cheesecake, ice cream, trifles, Bavarians, crème brûlée, pots de crème, and pudding all have in common? At the most basic level, these creamy desserts are all custards. Technically, a custard is any liquid thickened by eggs, and in most cases that liquid is cream or milk. It’s a marriage made in heaven: The creaminess of the dairy is enhanced by the silky, emulsifying properties of egg yolks to create an irresistible texture. I’ve turned down a cookie, even a slice of cake, but I don’t think I could ever turn away crème brûlée.

As you’ll see, different types of custards are governed by slightly different sets of chemical properties. Knowing the scientific principles behind them—plus a few key cooking tips and tricks—can help you get these luscious desserts right every time.

幻灯片：获取十几个以上的食谱scrumptious custard desserts。

Three types of custards

Custards are categorized by how they’re thickened.
Pure or basic custards are thickened and set by eggs alone. These are the most delicate custards; they require careful attention during cooking, which is usually done in the even heat of a water bath, as they can quickly go from undercooked to broken and curdled.

Starch-thickened custards contain ingredients such as flour or cornstarch for added thickening power. These starches give custards more body, making them sturdy enough to endure cooking with direct heat.

Gelatin-set custards have an alluring richness from the structural boost that only gelatin can provide.

The science behind basic custards

是什么使他们与众不同？These delicate custards are thickened only with eggs. When heated, the egg proteins slowly unwind from a coil-like shape and elongate. The proteins can then easily catch onto one another to form a gel, which thickens the mixture.

Delicious examples: Crème anglaise, a classic dessert sauce made with lightly sweetened milk and cream and just barely thickened with egg yolks, is the thinnest of all basic custards. If you freeze this custard sauce, you get ice cream. If you add more egg and bake it, you have flan, pot de crème, crème brûlée, or crème caramel. If you pour it over bread cubes and bake it, you’ve made bread pudding.

Getting them right: Sweet custards typically thicken between 160°F and 180°F, well below the boiling point. If you go past that point, the egg proteins lose their shape and can no longer hold liquid, so a baked custard like crème caramel will appear curdled and runny, and a stirred custard sauce like crème anglaise may have bits of scrambled egg in it.

为了防止过度煮熟，通常将基本蛋ust煮在双锅炉上或在水浴中烘烤。这些技术可确保缓慢，甚至烹饪，并提供一层绝缘材料，直接在燃烧器上烹饪根本无法烹饪，这太容易在直接火上烧焦精致的蛋ust。无论您是否使用双锅炉，在炉顶上烹饪基本蛋ust时，都会经常检查其温度，以确保其不超过180°F。当他们轻轻地在中心有轻微的摇摆时，从烤箱中取出烤蛋ust。剩余的热量将继续烹饪直到完全凝固。

The Science behind starch-thickend custards

是什么使他们与众不同？添加小麦粉（或玉米或马铃薯淀粉）使这些蛋ust呈浓郁的质地，并且额外的淀粉分子慢慢蛋白质凝结，使它们更具耐药性（尽管没有免疫）过度煮熟和凝结。虽然绝对不应煮沸基本的蛋ust，但淀粉厚的蛋卷需要达到低煮熟的锅，以确保它们完全煮熟。

美味的例子：从布丁到糕点奶油和芝士蛋糕，淀粉厚的蛋奶都会采取多种形式。布丁含有足够的增稠剂，可以给它们提供身体，但不足以使其僵硬。糕点霜较厚（其中包含更多的淀粉），这使其成为水果蛋或奶油派的坚固基础。经典的法国蛋ust克拉福蒂（Clafoutis）位于淀粉厚的蛋ust延长的另一侧，因为它包含淀粉与液体的比例相对较高。这使其可以在没有水浴的情况下忍受烤箱的直接热量。

正确地做到：淀粉厚的奶油必须慢火煮，以确保蛋黄中的淀粉酶酶已通过热量变性或使其无活性。搅拌蛋ust（如布丁和糕点奶油）尤其如此，这些奶油奶油易于在炉顶上煮熟。煮熟的蛋ust可能最初看起来很厚，但随着淀粉酶攻击淀粉并破坏蛋ust时，会慢慢变成汤。一个好的指南是在气泡出现在蛋ust中，不断搅拌后煮1到2分钟。

If you overcook a starch-thickened custard, you can use a fine strainer to strain out any bits of egg.

明胶固定蛋ust背后的科学

是什么使他们与众不同？Like eggs, gelatin contains proteins that bind liquid. But powdered gelatin is a much more powerful thickener than eggs, so it gives the custard enough body to hold its shape when sliced. This type of custard needs to be chilled in order to set.

美味的例子:蛋奶冻Gelatin-set开始智慧h a basic custard (such as crème anglaise), which may be flavored with fruit purée or chocolate. When gelatin is added to this mixture, it becomes firm enough to set in a crust for an icebox pie. Fold whipped cream into the gelatin-set custard and you have a fluffy, melt-in-your-mouth Bavarian. Bavarians can be poured into decorative molds to set, or used to fill a cake-lined pan. (A classic example is charlotte russe, which is a Bavarian cream set in a mold lined with lady fingers and garnished with whipped cream.) When egg whites are used to lighten the custard, you’ve got a chiffon filling, which makes lighter-than-air pies.

Getting them right: To ensure that the gelatin dissolves evenly without forming grainy lumps, allow it to “bloom,” or soften, by sprinkling it onto a liquid and letting it sit for 5 minutes before heating to dissolve.

某些水果，例如无花果，菠萝，猕猴桃，木瓜，芒果和番石榴，应在被用于明胶蛋奶蛋ust之前煮熟，以使可以分解明胶的酶。（这对于罐装水果不是必需的，在足够高的温度下进行巴氏杀菌以使酶变性。）

为了获得最大的体积，请让明胶固定的蛋ust冷却并稍微变稠，然后再折叠任何鲜奶油或打败的蛋清。