Macroanalytical Procedures Manual (MPM) Main Page

A. Method for Casein and Sodium Caseinate (V-26)

(1) Scope

This method describes a procedure for determining contamination in casein and sodium caseinate caused by discrete particulate filth from insects, birds, and other sources. The method involves direct separation of contaminants from the product by screening.

Casein is a white to yellowish granular protein precipitate made from skim milk by the action of dilute acid or rennet. Sodium caseinate, a white powder, is produced by treating casein with a dilute NaOH solution and then spray-drying the soluble material.

These products are used as protein supplements in dietetic foods, bakery products, stews, and soups. Sodium caseinate is also used as a binder, emulsifier, a whipping agent in food products, and as a prime constituent of nondairy cream.

(2) Applicable Documents

1. CPG 7106.7 Adulteration of Cheese Products with Filth

(3) Defects

These products may become contaminated with manure and plant fragments, insect and rodent filth, feathers, and other extraneous material.

(4) Procedure: Determination of Contamination Caused by Extraneous Material in Casein and Sodium Caseinate

1. Sample Preparation -- Draw a representative or selective number of analytical units from the sample, depending on the history of the lot.
2. Visual Examination -- Sift a minimum of 100 g of the subsample on an appropriately sized sieve. Examine for whole insects, rodent pellets, and other extraneous materials.
3. Report -- Report results, using the format in AOAC 970.66B(i).