The acidophilus milk containing Lactobacillus acidophilus differ in the type of starter culture and milk used for their preparation. Acidophilus sour milk, as the name indicates, is a sour milk beverage made out of standardized milk by acidifying it with pure culture of acidophilus rods. Milk cultures of L.acidophilus has the therapeutic value but does not possess the buttery acetaldehyde flavour of the regular fermented milk such as curd and yoghurt.

The milk meant for preparation of acidophilus milk is standardized to 3.5% fat and 8.5% SNF content.

The standardized milk is sterilized and cooled to 40°C.

The milk is then inoculated with 24 hours old pure culture of L.acidophilus at the rate of 2-3%.

It is filled into clean glass or plastic containers (200 ml volume) and incubated at 40°C for 8 hours.

The acidophilus milk is then cooled and stored at 5°C till it is consumed.

The acidophilus milk thus obtained is sour with 1 to 1.25% lactic acid and pH 3.7 - 4.0. The product should contain more than 2000-3000 million viable L.acidophilus organisms per ml, which possess satisfactory antibiotic effect against E.coli as well as other pathogenic and non-pathogenic undesirable bacteria of the intestinal tract. The viability of the organism is of primary importance in the use of the acidophilus milk. The acidophilus milk can be preserved up to a week, below 5°C.