The determination of milk powder added to whole milk.

The objective was to determine the adulteration of fresh milk with reconstituted full fat milk powder. The ultra violet and visible spectra (700 to 240 nm) indicated two empirical parameters which are used to detect and quantify adulteration. Each parameter was calibrated against standards of adulteration and then tested against samples of known adulteration. One parameter, tested against two known series (5, 10, 20, 40 and 80% adulteration) gave the best correlation (coefficient of variation, 2.9%) between 20 and 60% adulteration. Correlation decreased at 80% adulteration (coefficient of variation 6.7%) and at 0 to 20% adulteration (coefficient of variation 35.9%). The second parameter, used in the range of 0 to 10% adulteration, when tested against 14 known samples gave results with an average of 12.5% below the true values. Sensitivity was 2.5% added reconstituted milk powder. The effect of low fat values (less than 2.3%) is discussed and a correction factor derived. The method when tested against 12 known samples gave the correct result in all cases within the limitations of the method; 4 commercial samples of milk were also analyzed.