The dairy industry, because of fractionation, is now producing permeates such as lactose and minerals filtered out of milk and whey and is trying to find uses for them. Lactose is the most predominant component in milk, so the industry is trying to find new uses for the permeate.
WHICH SYSTEMS ARE AVAILABLE?
Two systems are available-
- The UF system operates at 80–100 psi, the RO system at up to 500 psi. UF removes two-thirds of the water, lactose, and ash from the milk, concentrating it 3.5 times. The permeate is currently used as animal feed, although the company is exploring other ways. Because of its smaller pore size, the RO membrane allows only water to pass through, concentrating everything else. The system is capable of separating a very clean lactose stream, without the acid damage typical of whey processing.
RO SKIM MILK VS RAW MILK
Reverse Osmosis (RO) plant is used in the dairy industry for the concentration of milk to reduce shipping volumes and transport costs.Milk is approximately 87 percent water and 13 percent solids.The milk concentration technology works by removal of water from the cooled milk using very small pores of RO-membranes. The cold temperature at 8 °C is used to prevent increase of bacteria and to maintain the quality of milk components.
Only water can pass through the membrane but milk components do not pass through the membrane. In this case the water is the permeate and the concentrated milk is theretentate. The typical comparison has been shown in the table below:
|
3X (RO) |
Fat % |
Protein % |
Lactose % |
Solids-Not-Fat % |
Volume (L) |
|
Raw Milk |
3,8 |
3,2 |
4,5 |
8,6 |
10.000 |
|
Condensed Milk |
11,4 |
9,6 |
13,5 |
25,8 |
3.333 |
The system on a dairy farm has 5–6 employees because it operates 24 hr/day. The cows are milked three times a day, so the flow of milk is on-going. High-producing herds produce 80–90 lb of milk per cow. A small plant is about 4,000 sqft in size, a large plant about twice that size. Small systems can process milk from 4,000 cows, and larger ones from 20,000 cows. The cost of the systems runs from $2.5 million to $5 million. Membrane processing is probably the most-used technology for separating components, but ion-exchange chromatography can also be used to separate the desired components. It is used to make whey protein isolate now, and there’s no reason why it can’t do with the milk stream.
