Production of whey protein concentrate (WPC) is often used when whey is to be turned into more valuable products than animal feed or whey powder. Whey proteins have a number of useful nutritional and functional properties that can be utilised in a wide range of products.
WPC products exist in a great number of varieties, from "simple" to highly specialised products with reduced fat content, modified protein composition, special functional properties, reduced ash content, etc.
WPC is commonly characterised either on the basis of its content of "protein in solids" (eg. WPC-80 has 80% protein in solids). The most valuable constituents of WPC products are the different whey proteins.
SPX FLOW's in-depth knowledge and active involvement in the development of the world's whey products industry, combined with proven experience in project management of major capital projects, makes APV the ideal partner for the design and installation of state-of-the-art whey processing equipment.
The range of WPC products is now so great that it is impossible to describe all the various process lines. The most commonly used lines focus especially on the ultrafiltration (UF) stage. Both sweet and acid whey may be used in the production of WPC.
For optimum design of the whole process line, and in particular the UF plant, it is important to know as much about the whey type as possible: its source, its composition and its "history". Important steps are:
- Removal of casein to secure proper ultrafiltration capacity.
- Separation of cream to reduce the fat content of the whey.
- Heat treatment to secure proper bacteriological quality. Acid whey should only be heat treated at lower temperatures.
- Pre-concentration by evaporation, reverse osmosis, nanofiltration or ultrafiltration is often used before transportation from cheese factories to WPC factories to reduce transport costs. This step will affect the design of the UF plant for the actual WPC production.
- "Additional pre-treatments" such as fat removal by microfiltration, demineralisation or enzymatic modifications, may also influence the design of the UF plant.
- pH adjustment of sweet whey to pH 5.8-6.0 is normally required.
The whey, no matter which type, is concentrated to the required total solids (TS%). On production of WPC up to approximately 70%, only concentration takes place, whereas on production of WPC to 80%, a diafiltration must also be carried out (washing out of lactose and ash). Diafiltration is almost always carried out when WPC is produced using preconcentrated whey.
After ultrafiltration, the concentrate is heat-treated, after which it is cooled and then preheated again for drying.
- WPC 35-50% is often evaporated, before it is dried to the final TS of approx. 95%.
- WPC 50-80%, which often has a TS level of 27-30%, can be pumped directly to spray drying.
Evaporation and drying
After ultrafiltration and prior to drying, further concentration of WPC may take place in an evaporator at low boiling temperatures. Drying of WPC is preferably carried out in a tall form dryer with nozzle atomisation.
The advantages of this type of dryer are a well-defined residence time and gentle heat treatment of the heat-sensitive product. The typical inlet drying air temperature is 175-190°C.
Some WPC producers prefer to avoid the drying step and instead produce a liquid WPC. The composition is equivalent to that of WPC-35, i.e. with the same protein/TS content as skim milk, and the product is generally used in-house as skim milk replacer in ice cream, yogurt and flavoured milk.
The production process is the same as for dried WPC up to the outlet from the UF plant. To prevent odours from the cheese manufacture from contaminating the final product, a deodorization step is required.
Process Diagram and Benefits
- SPX FLOW's global experience as a supplier of processing technology and equipment for whey products is a key factor in our ability to deliver cost-effective solutions tailored to individual customer requirements.
- We offer an enormous range of resources to the dairy industry in process engineering, equipment manufacturing, project management - for both large and small projects - and world-class development facilities.
- Our ultrafiltration systems deliver a number of benefits in the production of whey protein concentrate:
- Low protein loss in the permeate
- Possible to produce and WPI
- Better production economy
- Ability to produce WPC from both acid whey, sweet whey and pre-concentrated whey in the same plant