High content of mineral salts and lactic acid in whey complicates the development of technology for food and dairy products and provides organoleptic and specific defects and restricts its use in food applications.

 

Drying of acid whey with preliminary deoxidation. The process of drying of acid whey is negatively affected by high content of lactic acid. Reducing of the content of lactic acid is possible via its neutralization - such as by sodium bicarbonate (NaHCO3) or calcium carbonate (CaCO3). Curd whey with acidity 620Т is condensed to the content of solids approximately 20-24%, after which to the concentrate with temperature 50-550С the deoxidizer (CaCO3, NaHCO3, NaOH) is added. Deoxidation of the concentrate before drying helps to reduce thermal plasticity of the product, intensifies the drying process but the product has high hygroscopicity and cakes even when stored in a vacuum package. The concentrate is mixed till finishing the reaction and sent for further condensation.

 

Nanofiltration of whey. The use on nanofiltration plant for preliminary condensation of whey allows removing from whey up to 30% of lactic acid, mineral salts and 70% of moisture that facilitates its further processing.

 

Drying of curd whey demineralized by electrodialysis. The electrodialysis removes up to 90% of mineral substances from whey. The pH almost does not change; titratable acidity is reduced by 70%, the specific conductivity – by 80%. Electrodialysis of whey has no significant effect on the quality and content of the whey proteins, lactose and vitamins. Removal of salts during electrodialysis process allows obtaining the desalted solution of lactose (processing for lactose of high purity), demineralized lactose solution. A slight salt content in the condensed solution of lactose contributes to its rapid crystallization. As a result of the electrodialysis the organoleptic properties of dairy whey are significantly improved. Desalting of whey in its primary state and after its condensation up to solids concentration of 18-22% is possible. At desalting of natural whey the production costs are higher than at desalting of condensed whey by 15% at 60% and by 30% at 90% level of demineralization. Condensation may be carried out at various concentrations of solids: 15, 24, 50% or higher. If condensation is held up to 50% or higher - it is necessary to remove the formed lactose crystals. After the electrodialysis whey is finally condensed in the evaporator up to the concentration of 50-55%. Then the usual scheme of processing is used. The product has good flow properties and low hygroscopity (13-15%).

 

Heat treatment of acid whey:

  • Pasteurization at 63-650С with ageing 15-20 seconds;
  • Cooling to the temperature not more than 100С;
  • Condensation of whey at the temperature of 50-620С in the evaporator of any types.

 

Drying parameters are determined by the following factors:

  • Moisture requirements of the finished product;
  • The solids content in the concentrate before drying;
  • The degree of crystallization of lactose in the concentrate;
  • The amount of lactic acid in whey (titratable acidity, active);
  • The viscosity of the concentrate.

 

The main differences of the drying plant for drying whey:

  • Integrated fluid bottom where in the fluidized bed final drying of the product occurs;
  • Vibration chute wherein whey is cooled to the final temperature;
  • The use of the large-sized cyclone;
  • The system of blowing the walls;
  • The system of pneumatic tapping for elimination of accumulations and adhesion of powder on the chamber walls.

 

Temperature settings of drying of curd whey:

Inlet temperature - 160-175 °С, outlet temperature - 75-80 °С.

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