Solvent Extraction

To begin with, the beans are flaked and made oil-free through the hexane "flash desolventizing" process. Next the solubles (mainly sugars) are removed (dissolved) through extraction with aqueous alcohol. The product that remains is rich in protein. It is pressed in Vincent screw presses in order to remove as much remaining alcohol, water, and sugar as possible. Finally the product is run through a special desolventizing system to remove all traces of alcohol and to reduce the moisture to around 8%.

The presses used in this application are special. Since the soybean material performs much like sawdust or ground corn cob, very low press cake moisture (in the range of 50 to 56%) can be achieved. However, it takes more horsepower than normal and a very unusual screw is required in the press. This screw design was developed by Daniel Chajuss, of Hayes General Technology Company, a pioneer in the industry.

Furthermore, because of the alcohol that is present, the machines are made relatively explosion-proof. Bolted vapor tight covers are used throughout. Another feature is the use of bronze fasteners to prevent sparking. Under safety code V-belt drives cannot be used, so in-line drives are necessary. As a result, a VP-22 press presently under construction will be 29' long.

Higher horsepower drives, up to 60 hp on a VP-16 and 100 hp on the VP-22, are being offered. This has led to using stand-alone thrust bearings to support the screw (due to the severe axial loads encountered). Wedgewire screens are specified to reduce the incidence of screen plugging.

The protein concentrate is used as a premium ingredient in the food processing industry. Because of its blandness, palatability, and freedom from deleterious and antigenic components, as well as its ability to take flavorings, it is used to extend, and substitute for, many foods. It is used in meat, poultry, fish and milk products. It is also important as a milk replacement in feed for calves and piglets, as well as being used in pet foods. Soy protein concentrate is used in powder, textured and highly functional and soluble "refolded" forms.

This is an unusual market niche in which Vincent has specialized. While we are experts on the screw presses that are required, we refer broader technical inquiries to Hayes General Technology in Israel.