Soy protein isolate is mostly soybean protein that food producers separate for use as a dry powder ingredient, according to the Soyfoods Association of North America. Producers remove the fat from soybean flakes and wash them in alcohol or water to remove sugars and fiber.
One ounce of soy protein isolate powder contains 96 calories from 1 gram of fat, 2 grams of carbohydrates and 23 grams of protein, explains the Soyfoods Association of North America. It is a common ingredient in beverages and foods such as power bars, meat analogs, baked goods, cereals and muscle-gain products. Consumers can also purchase soy protein isolate powder by itself for use in shakes, smoothies or other meals.