Soy Protein
The soybean contains around 40 percent protein and is the most significant source of protein in the entire plant world. This protein furthermore contains precisely the amino acids the human body requires but cannot produce independently. As a result, many thousands of foods – including diet foods, baked goods, confectionery as well as sports drinks and baby food – contain soy protein. In addition, the protein also appears in technical products such as water-soluble paints, textiles and plastics, in cosmetics or packaging films.
Soy protein can be obtained in the form of a concentrate or an isolate. For both variants, the industry uses GEA Westfalia Separator process lines which ensure high product purity combined with a high yield and optimum installation hygiene. The recovery of protein is associated with low fresh water consumption and therefore a reduced waste water load.
To obtain soy protein concentrate, the soy flocs first have to be mixed with acid and process water before a 3-stage washing phase commences. Each of these washing stages is characterized by the fact that following washing, a decanter separates the solid from the liquid phase. The supernatants of the decanter are used as process water on the counter-current principle so this reduces total water consumption in the installation.
Integrated process line from GEA Westfalia Separator for obtaining soy protein concentrate
Following additional neutralization, pasteurization and drying, the protein / fiber mixture concentrated in this way has a protein content of at least 65 percent.
The second diagram shows the method for soy protein isolate. In this process, centrifuges from GEA Westfalia Separator are used for a total of five process stages.
Integrated process line from GEA Westfalia Separator for obtaining soy protein isolate
Initially, the proteins are extracted from the soy flocs in two stages. The fibers separated in the second stage which still contain bound and insoluble protein, are used as animal feed. The protein dissolved in the supernatant of the first and second decanter stages is fed to the precipitation stage after extraction. During precipitation, protein flocs form which are concentrated by a decanter. The proteins remaining in the supernatant can be recovered by a clarifier to increase the yield of useable protein and to reduce loading of the waste water. The remaining whey can be evaporated and used as molasses in fermentation processes.
The protein from the decanter and separator is then fed to the washing stage. Due to this step, soluble carbohydrates are further reduced and the protein content is increased. After further process steps such as neutralization and pasteurization / UHT, the soy protein isolate leaves the spray-dryer in powder form with a protein content of over 90 percent.
Process line for soy protein
