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Milk powder

Article index
 Production milk powder
 Vaporization
 Drying
 Separation
 Agglomeration
 Packaging
 Temperatures and properties
Milk powder is a dairy product that can be preserved for a long time thanks to water removal. In correct storage conditions (cool, dark, dry and air tight) milk powder can be preserved for years. By moisture removal its weight is about 1/7 of the weight of milk.
Milk powder is often used in bakery-, chocolate production and ready-to-consume meals.

Production milk powder

The only raw material for milk powder is milk. By water removal milk powder is obtained.
Before the water is removed, the milk is :
  • centrifuged,
  • standardised,
  • homogenised and
  • pasteurised or sterilised.
The dry matter content of milk is 13%.

Vaporization

After the above mentioned pretreatment, the milk is thickened is a multistage vacuum evaporation installation.
After thickening the milk has a dry matter content of 50%. Further thickening is not possible as the flow characteristics at this high dry matter content is bad. Multistage evaporation installations consume less energy. The vapour of the first stage is used in the second stage and so on. Evaporation with this installation is in many cases more economical than spray drying. Evaporation is performed under vacuum as than the boiling point of milk is lowered to 70°C. Sometimes the temperature of the last stage is lower than 65°C.

Drying

The thickened milk is dried to powder in an atomiser. In the upper part of the atomiser hot, dry air (T = 150–250ºC) with relative humidity (RV) of less than a 0,5% is blown, together with small droplets of milk (T = 0-20ºC and aw = 0,98). The milk has instantaneously a high temperature (T = 50ºC) and transfers his moisture to the hot air. Downstairs the atomiser (tower), the output is air with high humidity (T = 90ºC en RV = 14%) and dry milk powder (T = 70ºC and 92-96%). In the atomiser the residence time of the droplets is between 8 and 30 seconds.

The milk droplets in the atomiser can be produced in two ways:
  • High pressure atomization: the droplets are formed by pressing the milk through small nozzles at very high pressure. This way gives an uniform droplet size, and also the powder has an uniform grain size.
  • Disc atomization: the droplets are formed by injecting the milk on a disc turning at high speed (larger than 6000 rpm). The milk is atomized. The droplet size varies from large to very small. Powder of coarser and smaller size is obtained.

Separation

After atomization the hot air is separated from the powder with a cyclone. In a cyclone the coarser product stream (powder) is travelling to the outside and falls downstairs along the wall. The air is leaving along the middle above end through a rotating lock. The powder is transported to a mixer and filling machine.

Agglomeration

Milk powder is agglomerated to enlarge solubilisation. Moreover, lumping is reduced.
Grains of milk powder are agglomerated by moistening with vapour. The powder is moving upstairs in a fluidized bed, lumps together and grains are formed.

Packaging

By storage in light- and air-tight packagings milk powder can be preserved in cool circumstances for years.

Temperatures and properties

Temperatures and properties of the powder
The process occurs at different temperatures. At high temperatures the moisture is vaporizing more quickly , but the milk powder is losing properties that the milk possesses. At lower temperatures the evaporation proceeds slower, but the milk powder maintains better the properties of milk.
  • Low-heat milk powder:
Low pasteurised milk: at evaporation the temperature is maintained under 70ºC. The temperature of the milk droplets during spray drying is low. Hence the temperature of the exit powder is low. The milk powder contains no denatured milk protein, making the powder curdling during cheese prepartion and good soluble. As the powder is diluted to milk, there are no problems with taste.
  • High-heat milk powder:
The pasteurisation of the milk is 5 minutes at 90ºC or 1 minute at 120ºC. With bad hygienic design thermophilic micro-organisms can develop at these temperatures and continuous contamination can occur. Through denaturation of the milk protein high-heat milk powder is badly soluble. The high temperatures during this process gives the milk powder a boiling smell and taste, especially with full fat milk powder. Curdling of the powder during cheese production is bad. But for addition to baby food this is an advantage. High-heat milk powder can be easily applied in soured products (like yoghurt). As the milk own bacteria inactivating system is inactivated, fermentation mixtures are not inactivated. High-heat milk powder gives to yoghurt extra high viscosity.

User comments

2008-04-09 09:15:48

Name: S Groenenboom
Wordt van melkpoeder ook wel melk gemaakt die in supermarkten in melkpakken wordt verkocht?

2008-04-09 09:18:42

Name: editor
Beste heer Groeneboom,
In principe zou dat kunnen. Het levert echter melk op die minder smaakvol is dan gewone, en met de extra handelingen en de huidige prijzen voor melkpoeder is het veel te kostbaar. In Nederland is melk van aangelengde melkpoeder niet te koop.

2009-07-01 13:59:10

Name: Patrick Laenen
is er een verschil in het productieprocess ivm de kwaliteit van het eindproduct? Ik neem aan dat poeders voor babyvoeding aan andere normen moeten voldoen dan poeders voor de bereiding van maaltijden, of is dit niet zo?

2009-07-03 12:28:37

Name: Editor
Ja, er bestaat kwaliteitsverschil. Er worden m.n. strengere eisen gesteld aan de aanwezigheid van E.sakazakii.

2011-12-14 22:40:40

Name: ekici
Beste,

ik vraag me af of er melkroom in poedervorm bestaat? Volle melkpoeder heeft een percentage tussen 24~26%. ik ben opzoek naar een product waarvan de percentage hoger ligt.

2012-01-13 08:28:05

Name: Gerrit van Koningsveld
Er bestaan inderdaad ook roompoeders, met een melkvetgehalte tot 75-80 % op droge stof

2012-12-17 17:25:22

Name: johan bloom
Ik wilde weten of van de roompoeders
haast bijna echte melk gemaakt
Kan worden.
Ik wil zelf melk maken als soort noodvoorziening
Als ik de deur effe niet uit kan.

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process description

milk powder, cream powder

Milk powder is a dairy product that can be preserved for a long time thanks to water removal. In correct storage conditions (cool, dark, dry and air tight) milk powder can be preserved for years. By moisture removal its weight is about 1/7 of the... read full description
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