How can you get Lactoserum

How can you get Lactoserum? For many people this is a strange object, and here's the introduction to it:

Whey usually refers to the by-product of the milk production of cheese. Whey is a green, translucent liquid that is separated from the milk when the milk is condensed into a curd. With the development of new technology, whey and whey protein have become food raw materials with high value and wide application. In general, milk includes 2.8 percent casein and 0.7 percent whey protein. Compared with casein, whey protein has better solubility and higher quality essential amino acids. In the protein world, whey protein has so far been considered the gold standard. The protein of animal source is much higher than plant protein. In the protein of animal origin, protein in milk, especially whey protein