Developments within the industries using whey products and powder have transformed this high nutritional by-product into a valuable product.

TWO GROUPS OF WHEY PRODUCTS

  • Sweet whey products. Also referred to as cheese whey, is produced during cheese-making, when rennet is applied. This group forms a large family of products with very similar composition, whereas their properties are very different. The pH value of sweet whey can range between 5.2 and 6.7.
  • Sour whey products. These may include acid whey, quark or cottage-cheese whey and sour sweet whey. Acid whey, also known as casein whey, originates from the manufacture of casein by means of lactic acid and hydrochloric acid. The origin of quark or cottage-cheese whey is self-explanatory. Lactic acid created through natural fermentation gives the whey a high acidity. The pH values of this group range from 3.8 to 4.6. If insufficient care is given to the cheese whey, natural fermentation makes it sour. This process is obviously undesirable since soured (not sour) whey is not considered a natural product.

SPRAY DRYING WHEY PRODUCTS

Whey products can be spray-dried, but do however, require their own handling techniques. Plant design for spray-dried whey may vary from simple to sophisticated. Generally speaking, sweet (cheese) whey is easier to dry than acid whey. The main operations in the production of whey powder are as follows:

  • Preheating
  • Concentration
  • Flash cooling
  • Pre-crystallization
  • Spray drying
  • Cooling in a vibrated fluid bed

    • SPRAY DRYING WITHOUT CRYSTALLIZATION TREATMENT

    This process consists of preheating, concentration, spray drying and pneumatic cooling.

    Whey powder produced by this process is very delicate, dusty, hygroscopic and therefore caking. Hygroscopicity and caking are influenced by the type of whey and by local climatic conditions. The hygroscopicity, caking and all the problems associated with the stickiness of ordinary whey powder are mainly due to the presence of lactose in the amorphous state.

    Lactose is in an amorphous state and unstable in atmospheric air or normal humidity, during the spary drying process. The a-lactose monohydrate is the only form, which remains stable when encountering humidity. The lactose content of whey powder comprises more than 70% of the total solids in comparison with 30% in whole milk, making the problem more severe.  However, since the solubility of lactose is 17 g/100 cm3 H2O at 20°C, it is easy to control the drying process in such a way that a majority of the lactose can be transformed to the stable a-lactose monohydrate form during the drying process.

    PRE-CRYSTALLIZATION AND CRYSTALLINE TREATMENT

    The basic process layout is modified by making a pre-crystallization before spray drying.
    Viscosity of the concentrate is reasonably low, the temperature is exactly adjusted and controlled, displacement of used solution from the surface of crystals may be accelerated by agitation, and the required amount of suitable crystals of lactose may be ensured by proper seeding. During the pre-crystallization process there is enough time to reach the theoretical degree of crystallization.

    This product provides a non-caking product to be agglomerated. The agglomerates tend to be small and thus the bulk density is relatively high.

    The drying chamber with integrated fluid bed is fitted with pressure-release vents and a fire-extinguishing system. Cyclone, bag filter and external vibrating fluid bed have similar safety features. The cyclone(s) and bag filter may today be replaced by a sanitary bag filter to improve operating costs.

    CHOICE OF WHEY PROCESS

    The choice of process depends upon the type of whey available, the intended market for the whey powder and the plant location. The ability to handle sweet whey and yet produce a non-caking product requires a simple layout. If the dried powder is intended for dry powder mixes, flow ability is essential and the process must be equipped with crystallization and cooling stages achieve this. Local climate should also be considered, plants in a humid climate are recommended to use a process, which produces a less hygroscopic product with low caking tendencies.

    FRACTIONATION OF WHEY

    Instead of producing ordinary or pre-crystallised whey powder, it has proven worthwhile to install a ultra-filtration plant, when large amounts of whey is available. The whey is divided into two fractions. A retentive comprising WPC (whey protein concentrates in different grades 35, 60 or 80) or even WPI (whey protein isolates with protein content higher than 90% on solid basis) and a permeate.

    The permeate can be evaporated further to produce lactose in different grades. During this process, it is possible to remove the valuable mineral calcium phosphate.

    For the production of whey protein, a standard Tall Form Dryer, TFD with VIBRO-FLUIDIZERŪ is used. The atomization takes place by means of nozzle atomization at a pressure of up to 350 bar.

    WHEY PRODUCT TEAM

     A group of GEA companies have experience handling whey products in individual segments, such as pre-treatment, clarification, fractionation evaporation, spray drying and packing. These companies make up the Whey Product Team. This team's experience can be drawn upon, assisting and advising the installation of a whey treatment line adhering to the client's specification.