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Quotes - Engineering - SalesA pasteurizer that runs next to the coagulation point
Liquid egg is the one food product where the legal pasteurization temperature and the temperature at which the product is ruined sit within ten degrees of each other. Whole egg goes to 140 F and holds 3.5 minutes; egg white goes to 134 F; plain yolk to 142 F; yolk with 10 percent salt or sugar to 145 F. Above roughly 150 F the albumen proteins begin to set, and the first place they set is the film of product touching the heating surface. An exchanger adequate for milk will cook egg onto its own walls before the first tote is full.
That is why the design conversation on egg is about wall temperature before it is about area. The heating medium is hot water a few degrees above setpoint, the surface is long and the approach is small, the product path has no gasket corner for protein to lodge in, and the cooler after the hold takes the product to 40 F in minutes. Viscosity runs from about 10 cP for white to 150 cP for salted yolk, which puts the whole family in tube-in-tube or wide-gap plate construction rather than a standard plate pack.
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Pasteurized at 140°F, ruined near 150°F: the approach is everything
Whole egg holds 3.5 minutes at 140°F on hot water just 2 to 4 degrees hotter, so the heater carries 60 to 80 percent more surface than a milk line. Regeneration stops at 75 percent so raw egg never touches a 138°F wall.
Tubular egg pasteurizer
- Corrugated or plain inner tube, 1 to 2 inch bore by product
- Hot water at setpoint plus 2 to 4 degrees, never plant steam
- Regeneration 50 to 75 percent, product against product
- Holding coil cut for 3.5 minutes at the fastest particle
- Inner tube pulls for the inspector; 316L, 32 Ra or better
Wide-gap plate for white and thin blends
- Doubled channel gap, low shear, foam-tolerant
- Regeneration to 80 percent on thin white
- Hold in an external sloped tube, not in the plates
- Opens for gasket and plate inspection between runs
- Chilled water then glycol cooling section on the same frame
Recommended construction by egg product
Viscosity and foam decide between tubes and wide-gap plates; the pasteurization temperature decides how tight the approach has to be.
| DUTY / CONDITION | RECOMMENDED CONSTRUCTION | WHY |
| Whole egg, 140 F for 3.5 minutes, 30 to 60 cP | Corrugated Tube | Corrugation keeps the coefficient up at a 3 degree approach so the heater is a practical length; single smooth product path |
| Egg white, 134 F, 10 to 15 cP, foams under shear | Wide-Gap Plate | Low shear across a wide channel keeps air out of the pack; regeneration is better than tubes on a thin fluid |
| Plain yolk 142 F and salted or sugared yolk 145 F, 100 to 150 cP | Single Tube-in-Tube | Large bore at low velocity for the thickest and hottest egg product; wall temperature controlled by hot water alone |
| Scrambled mix, egg with milk, cheese or starch, 100 to 300 cP | Multi-Tube | Parallel tubes give the area a viscous blend needs without a 400 foot single tube; drained and CIP-cleaned as one unit |
| Post-hold cooling of any egg product to 40 F | Double-Wall Plate | Glycol cooling with a leak-detect air gap where the plant will not accept single-wall separation from the refrigerant loop |
| Hot water set feeding the pasteurizer from plant steam | U-Tube | Steam on the tubes, water on the shell, controlled to within 1 degree; keeps steam temperature two vessels away from the egg |
How an egg pasteurizer is sized
Start with the approach. On milk a 5 degree approach is comfortable; on whole egg at 140 F it is the upper limit, and on white at 134 F it is closer to 3. The hot water set is held at 142 to 144 F for whole egg and the heater is sized with that small driving force, which means a lot of surface, 60 to 80 percent more than a milk line of the same flow. Corrugated inner tubes recover part of that by raising the product film coefficient 30 to 50 percent without adding shear, which is why they are the default for whole egg and yolk.
Then the hold. At 3.5 minutes the holding tube on an egg line is long, several hundred feet of sanitary tube coiled or stacked and sloped to drain. Egg is shear-thinning and runs in transitional flow, so the fastest particle can move at up to twice the mean velocity and the coil is cut on that ratio, then validated with a salt or dye pulse at the line's flow.
Then the cooler. Pasteurized egg has to reach 40 F before it goes to a tote, bag or aseptic filler, and the plant wants it there quickly because the 100 to 140 F range is where surviving organisms grow fastest. Regeneration takes the product to 80 or 90 F, chilled water to about 50 F, and glycol at 26 to 28 F finishes to 40 F, sized on the cold-end viscosity.
The common mistake is treating the regenerator as free heat. Pushing regeneration past 75 percent on egg narrows the approach on the hot side of the regenerator until the raw product touching that wall sees pasteurized product at 138 F, and it starts to cook there, in a section nobody expects to foul. HeatX sizes the regenerator for 50 to 75 percent and puts the balance on controlled hot water.
Wall temperature, hold length and the cooler
Foam and shear
Egg white whips at the slightest shear, and air in the pasteurizer means an air-bound holding tube and a product that will not meet the hold. The product pump is a low-shear positive displacement type, the pack or tube runs flooded with a vent at the high point, and velocities are kept to 1.5 to 3 ft/s. White runs on wide-gap plates for this reason: wide channel, low pressure drop, a fraction of a corrugated tube's shear.
Regeneration pressure and separation
Where raw and pasteurized egg share a regenerator, the pasteurized side runs at least 1 psi above the raw side, with a booster pump and pressure switch interlocked to the flow diversion valve, so that any pinhole leaks pasteurized into raw and not the other way.
Cleaning an egg line
Egg protein comes off with 1 to 1.5 percent caustic at 160 to 170 F for 30 to 45 minutes, followed by an acid step for the mineral film and a chlorinated or peracetic sanitizer. Plants running whole egg expect 6 to 8 hours between cleanings; white and salted yolk are shorter. The removable inner tube is for the inspector's flashlight, pulled on a schedule the plant sets with its regulator.
What to send
The product or products, flow in lb/h, inlet temperature from the breaker, pasteurization temperature and hold, outlet temperature, and the hot water, chilled water and glycol available. Call and talk it through with an engineer: 1-805-484-2992
Common FAQs
Egg white can, on a wide-gap pack with an external holding tube. Whole egg and yolk build protein at the plate ports and gasket corners within hours; those products run in tubes.
142 to 144 F, controlled within 1 degree. A 10 or 20 degree approach that would be normal on juice cooks a film onto the wall in the first hour and shows up as specks in the product.
For 3.5 minutes at 2 ft/s mean velocity with a fastest-particle ratio of 2, about 840 feet. The exact length is set by validation at the line's flow, and HeatX supplies the coil built to that length with the required slope.
Size the heater for the product with the tightest approach, usually salted yolk, and the cooler for the most viscous. The setpoint changes per product and the holding tube is validated for each.
Egg is near neutral pH and not corrosive, but salted yolk carries 10 percent salt at 145 F and the CIP is chlorinated. 316L on the product side is the standard HeatX quotes; 304L is acceptable on the utility side.
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