Materials used for making yogurt vary depending upon the recipe. Ingredients come from a variety of places. For instance, goat, cow, and sheep’s milk provide different sources of milk. Additives are also used in yogurt. A stabilizer is used to keep the product stable. Gums, gelatins, and cellulose are examples of stabilizers. Other additives like emulsifiers and preservatives can be added. Emulsifiers such as egg yolk, soy lecithin (soybean component that can occur in plant tissue), and additives like flavors, sweeteners, and coloring are added too. Preservatives are used to prolong the shelf life of the product. Fruit is an optional additive that is used to provide flavor, texture, and sweetness to a batch of yogurt. Bacteria cultures are also added. The bacteria used in yogurt is not the same kind of bacteria that makes someone sick. It gives yogurt its specialized flavor, and is beneficial to the gastrointestinal tract.