Samples Characterization of Commercial Regular and Lactose-Free Milk by Raman Spectroscopy

摘要

The objective of this study was to verify the presence of lactose in whole and semi-skimmed bovine milk samples, and the absence of the same in samples of “lactose-free” milk by means of Raman spectroscopy. Samples of milk were obtained in local markets and divided into two groups: semi-skimmed milk and lactose-free milk. The samples were homogenized and an aliquot of 80 ul of milk was taken for reading on a Raman spectrophotometer (830 nm 250 mW) and the spectra were treated by principal component analysis (PCA). The Raman spectra presented peaks related to milk composition (proteins, lipids and carbohydrates) and particularly the zero lactose samples showed glucose and galactose peaks and showed no lactose peaks. It was also verified the different in the intensity of the fat peaks between the whole and semi-skimmed samples. The Raman technique associated with PCA was able to identify the presence of lactose due to its characteristic peak of glucose and galactose in lactose-free samples. It could be used as a fast, simple and non-reactive alternative for the identification of milk composition.