Fourier Transform Infrared Determination of Whey Powder in Nonfat Dry Milk

Abstract

Infrared spectroscopy was used to measure the level of whey protein concentrate in an adulterated sample of NDM. Three samples of NDM (including high and low heat processed samples) and three whey protein concentrate powders with protein and lactose concentrations similar to those in NDM (34% protein and 50% lactose) were obtained from various sources. One hundred thirty-five blends of NDM containing various concentrations of whey protein concentrate (1.26 to 33.00%) were analyzed at wavelengths between 1400 and 1200 cm–1. There was a strong correlation (r > .99) between predicted and measured concentrations of whey protein in adulterated samples. The detection limit was 5.6% whey protein concentrate. Accuracy was not affected by processing conditions, source of NDM, or origin of whey protein concentrate powder. © 1991, American Dairy Science Association. All rights reserved.