Whole cow’s milk is composed of about 88% water, plus 3-4% proteins made up mostly of whey and casein (also called curds), 5% sugar in the form of lactose, and 3-6% fat. Milk is slightly acidic, about 6.5 Ph, and contains, salt, calcium and other minerals. Reduced-Fat Milk, formerly called 2%, has a reduced fat content, and Non-Fat Milk, also known as skim milk, has nearly all of the fat removed.
Half & half, light cream, and heavy cream are derived from milk production and contain higher butterfat making them thicker and richer in taste and texture.
Culinary Preparations with Dairy Products
In cooking and baking milk adds moisture and flavor. It also provides body and the sugars in the milk help in Maillard browning. Proteins in milk will easily coagulate and curdle if not stabilized with starch such as a roux.
Milk can be foamed but does not hold its shape well. The process of foaming milk for espresso coffee drinks is tricky because foams hold better when cool rather than hot. Steaming the milk just on the surface creates bubbles that heat enough to unfold the whey proteins into a web. Skim milk tends to create greater volume.
Milk and cream will curdle through the addition of acids such as vinegar, lemon juice or citric acid. Fresh cheese can be made by simply warming the milk or cream to 180-190°F with some acid and salt. The curds will coagulate on the surface and can be drained through cheesecloth.
Cream is a very stable product and can be heated and even boiled without the fear of curdling. That’s because the butter fat in the cream surrounds the casein proteins to keep them from coagulating. Only heavy cream with 30-40% butterfat will form a stable whipped foam.
Freezing milk or cream is not recommended as it breaks up the fat and proteins and creates a curdled effect. Pasteurized milk stored below 40˚F/5˚C should remain drinkable for 10 to 18 days.
Cultured Dairy Products
Milk or cream is sometimes combined with bacterial cultures to create thickened products that usually have a fermented or soured effect. Crème Fraîche, a French cultured cream can be used interchangeably for cream. Mexican Crema Fresca is a similar type of cultured cream and used the in the same way. Sour cream is an American cultured cream that is very thick and more acidic. Yogurt is treated with lactic acids that thicken it and give it a light tang.
Butter consists of minimum of 80% fat and 16-20% water protein, lactose, and salt making up the remainder. The liquids in butter are referred to as milk solids. Some European style butters will contain 82-85% fat. Butter usually comes as unsalted sweet cream or salted butter varieties. The salt will extend the shelf life but unsalted butter is used more in professional cooking and especially baking and pastry production. Cultured cream butter is common in Europe using lightly soured raw cream. Salted butter contains 1-2% salt.
Culinary Preparations with Butter
Clarified butter, also known as ghee in Indian cooking, is better for high-heat cooking because it has a smoke point of between 450°F and 475°F, as compared with about 300°F/150°C for whole unclarified butter. It has a longer shelf life than ordinary butter and can be kept at room temperature.
- Butter is an emulsion of fat and liquid.
- Butter provides richness and mouth feel.
- Butter is versatile by itself, as an emulsifier in sauces, or as a cooking medium.
- Whole butter will burn more easily because of the milk solids.
- Clarified butter removes the milk solids which raises the smoke point and extends the shelf life.
- Butter is browned intentionally in some culinary preparations to add flavor.