As you may know, there are four basic states of matter. Solids, liquids, gasses, and plasma. Today, we’ll be talking about liquids as they play an integral role in many baked goods, including pies. They come in nearly as many forms as there are varieties of baked goods.
In case you forgot your 6th grade science class, let's get a refresher on what a liquid is. A liquid is a state of matter that conforms to the shape of the container it is in, and maintains a relatively constant density. Water is a liquid, and the most versatile one when it comes to...well, everything. The properties of water lend itself well to use in baking and cooking, with methods such as steaming, simmering, and boiling all requiring water.
In the case of pie, water isn’t the only liquid you can use. There are many kinds, in fact, ranging from cream and vinegar to eggs and alcohol. Each has their own uses and functions, some of which wouldn’t initially be apparent to the uninformed.
Water: As previously discussed, water has many uses when it comes to baking, mainly in the form of acting as a good medium for the various chemical reactions that occur during baking. In addition, water is what generally allows dough to form and keep the mass together and not a bunch of buttery crumbs. This functionality is due to water causing the formation of gluten.
Alcohol, or specifically, Vodka: I know what you’re thinking: Vodka? In my pie crust? Well, it’s more common than you think. Pie crust made with vodka instead of water will be more moist, and have a more supple texture. The vodka passes along no flavor, unlike some liquids used in baking. The reason for this is due to vodka not causing the same gluten-forming reaction water does, and having a much lower boiling point than water, causing it to cook off faster than water.
Creams and Dairy Products: Cream is a white or yellow, thick substance derived from the milk of cattle or goats. Both the regular milk and cream from cattle can be used in baking, each with their own specific uses. Cream is useful for making whipped cream and fillings, as well as for making heavier confections such as ice cream. Regular milk tends to be thinner, and therefore is useful for baked goods requiring a overall softer dough or batter, such as pancakes, muffins, or biscuits. Baked goods containing either of these will also brown more easily, allowing for the perfect, golden color.
Vinegar: Although rarely the sole liquid in a recipe, a splash of vinegar is frequently called for in many pie crust recipes. The main reason many say this is to alter the strength of gluten strands in the resulting product, although this is only a measurable metric if you have a mass spectrometer lying around. There are two actual reasons to add vinegar, which are to prevent the crust from oxidizing and turning grey. The oxidation of non-vinegar dough has no harmful effects on the flavor or edibility of the final product, it can cause the dough to not hold shapes as well, which can be bad if you’re going for a fancy crimped crust.
Eggs: The most frequent way we use eggs with our pies is by brushing the tops of latticed or full crust pies with an egg wash. Eggs can be used in the actual pie crust recipe, however, and tend to make the crust easier to roll out and more pliable. Keep in mind you will have to ensure to be a little more careful with egg-based pie crusts, as eggs can contain harmful bacteria when raw. This won’t be an issue when it’s cooked, but when raw it will help to be more cautious about washing hands and cross contamination. We’ll talk more about eggs and their effect on crusts in a later post, as this isn’t an exhaustive explanation.
As you can see, liquids play an important role in the creation of not just pie crust but also other baked goods. Without some sort of liquid component, pie crust would be less of a flaky, delectable pastry and more a burnt pile of flour.
Fun Fact: We considered including oil in this post, but decided against it because we talked about it in our last post. Oil can act as both the liquid and the fat component of a pie crust, and the use of vegetable oils such as canola oil is actually an easy way to make vegan-friendly pie crust. You don't even need to use expensive vegan butter or other vegan substitutes!