Peanut butter is a blend of ground roasted peanuts, vegetable oil and salt. Some brands contain sugar or a stabilizer that prevents the oil from separating. By law it must contain at least 90 percent peanuts. There are two types of peanut butter: creamy and chunky. Chunky has chopped peanuts added. Commercial brands of peanut butter can be stored after opening for three months at room temperature or longer if refrigerated. Natural peanut butters that are 100 percent peanuts contain no additives to keep them from separating. They need to be stirred before using. Natural peanut butters should always be refrigerated after opening. They will keep up to 6 months. Peanut butter is used primarily as a bread spread and as an ingredient in cookies, candies, and sweet and savory sauces.