TVP is made from a mixture of proteins extracted primarily from soybeans, but also cotton seeds, wheat and oats. It is extruded into various shapes (chunks, flakes, nuggets, grains, and strips) and sizes, exiting the nozzle while still hot and expanding as it does so. The defatted thermoplastic proteins are heated to 150-200°C, which denatures them into a fibrous, insoluble, porous network that can soak up as much as three times its weight in liquids. As the pressurized molten protein mixture exits the extruder, the sudden drop in pressure causes rapid expansion into a puffy solid that is then dried. As much as 50% protein when dry, TVP can be rehydrated at a 2:1 ratio, which drops the percentage of protein to an approximation of ground meat at 16%. High quality TVP can be mixed with ground meat to a ratio of up to 1:3 (rehydrated TVP to meat) without reducing the quality of the final product, sometimes improving it if the meat used is poor. TVP is primarily used as a meat substitute due to its very low cost at less than a third the price of ground beef, and when cooked together will help retain more weight from the meat by absorbing juices normally lost.