To obtain a good dispersibility of a powder it is necessary that the powder is wettable and that the agglomeration is optimal, i.e. no fine particles should be present.
The analytical method is very difficult to define and perform and the reproducibility is very poor. There are numerous methods, and the results cannot be compared.
Being aware of that, IDF has developed a new dispersibility test. This test is based on determining the capability of a powder (25 g of skim or 34 g of whole milk powder) being poured on a surface of water (250 g, 25ºC) to disintegrate into particles capable of passing through a 150-micron sieve when applying the prescribed manual stirring for 20 sec. The amount of powder passing the sieve and being dissolved or dispersed is found by the determination of total solids of the filtrate and expressed in percentage as dispersibility