Lactose is a by-product of milk. Today, lactose is widely used in the pharmaceutical, food, and confectionery industries. The purest form of lactose is used in pharmaceutical applications as an excipient. It is a compound that is chemically inert, aids in the manufacturing process, and enhances bio-availability. The first major use of lactose was as a medium to grow penicillin, but it is now more commonly used as a binder and filler in tablets and capsules. Lactose’s use in food and confectionery products stems from its low sweetness, ability to bind flavorings and capability to increase shelf life. As human milk contains approximately 7% lactose compared with bovine milk content of 4-5%, it is added to cow’s milk in the preparation of infant formula.
Lactose is also used in the production of other compounds like Lactitol, which is used in diabetic products and low calorie sweeteners.
The worldwide market for dairy ingredients, including milk powder, whey ingredients, and lactose, was approximately 42 billion dollars in 2013 and is expected to grow to over 50 billion dollars by the end of 2018. The current global market demand for dairy products and ingredients has a compound annual growth rate of 2.8%. This exceeds the current global milk supply growth rate of around 1%.
Lactose is a simple sugar in milk and is a major component of whey. Lactose is purified from the whey produced as a byproduct of the cheese and casein industries. Several million tons of lactose is produced annually. Lactose is purified to make food and pharmaceutical grade lactose in a process shown here involving evaporation, crystallizing, centrifuging, filtering, drying, and milling.
Since lactose is classified as an ST-1 explosion rating, the milling system must be designed to safely handle any dust explosion. The system shown here is designed for an over-pressure situation with Isolation valves on the inlet and outlet of the system.
There are a few options for size reduction systems to process lactose depending upon the final particle size required. The Mikro UMP Universal Mill is capable of the fine grinding of lactose from 500 microns to 25 microns. The mill is available with different grinding elements and will produce a final product with good flow characteristics and a low amount of fines.
Air classifier milling systems offer the additional advantages of sharp top-size control, steep PSD distribution, ease of operating parameter adjustments, and cooling of heat sensitive products due to the higher air flow requirements of that type of system.
One of the most important factors in the mill system design is an ability to clean the mill and system. The Mikro ACM Air Classifying Mill – Model EA is equipped with a hinged cover for easy access. The internal components are designed to be easily removed for cleaning. In principle, all the components of smaller systems can be washed in place (WIP) or easily dis-assembled for cleaning. As an example, victaulic couplings can be used to quickly disconnect the system ductwork for cleaning.