Centrifugation in the Dairy Industry

Centrifugation and Separation

• Centrifugation is used in the dairy industry for clarification, skimming, standardizing, whey separation, bactofuge treatment, quark separation, and butter oil purification.
• Centrifuges can separate and clarify at the same time, with dense particles thrown to the perimeter, forming solids that collect in the centrifuge.
• Modern self-cleaning centrifuges allow for continuous separation/clarification, with a specially constructed bowl that can eject 8 to 25 L of sediment every 60 min.

Centrifuge Components

• A centrifuge consists of up to 120 discs stacked together at a 45 to 60 degree angle.
• Milk is introduced towards the inner edge of the disc stack through vertically aligned distribution holes.
• Dense phase moves towards the bowl wall, along the underside of the discs, while light phase moves towards the center, along the upper faces of the discs.

HTST Pasteurizer Components

• Balance tank provides a constant milk supply, with a float valve assembly controlling the liquid level.
• Regenerator utilizes the heat content of pasteurized milk to warm the incoming milk.
• Timing pump draws product through the raw regenerator and pushes milk under pressure through the pasteurized regenerator.
• Holding tube must slope upwards 1/4″/ft in direction of flow to eliminate air entrapment.
• Indicating thermometer is the most accurate temperature measurement.

Pasteurization

• Pasteurization is used to make milk and milk products safe for human consumption by destroying all bacteria that may be harmful to health (pathogens).
• It improves the keeping quality of milk and milk products, destroying some undesirable enzymes and many spoilage bacteria.
• Shelf life can be 7, 10, 14, or up to 16 days.

Pasteurization Methods

• Batch method: milk is heated to 63°C for 30 min, then cooled to 4°C.
• Continuous process method: saves time and energy compared to the vat method, using a high temperature short time (HTST) pasteurizer with a plate heat exchanger.
• HTST pasteurizer maintains a higher pressure on the pasteurized side of the heat exchanger, with a holding time of 15s at 72°C.

UHT Methods

• Direct heating systems: injection, infusion
• Indirect heating systems: plate, tubular, scraped surface

Packaging for Aseptic Processing

• Fill and seal: preformed containers made of thermoformed plastic, glass, or metal are sterilized, filled in aseptic environment, and sealed.
• Form, fill, and seal: roll of material is sterilized, formed in a sterile environment, filled, and sealed.
• Erect, fill, and seal: using knocked-down blanks, erected, sterilized, filled, and sealed.
• Thermoform, fill, and seal: roll stock sterilized, thermoformed, filled, and sealed aseptically.
• Blow mold, fill, and seal

Homogenization

• Homogenization is a mechanical treatment of the fat globules in milk, achieved by passing milk under high pressure through a tiny orifice.
• Milk is an oil-in-water emulsion, with fat globules dispersed in a continuous skim milk phase.

Explore the process of centrifugal separation in the dairy industry, including its various uses such as clarification, skimming, whey separation, bactofuge treatment, quark separation, and butter oil purification. Test your knowledge on this essential technique for dairy production.