Fraudulent addition of foreign substances is a usual form of milk adulteration in some countries, usually to disguise poor quality parameters or even other illegal practices, such as water addition to the milk. For example, formaldehyde and hydrogen peroxide are illegaly used to reduce microbial countings, while bicarbonate is used to neutralize lactic acid formed during microbial growth. To date, not much is known about the influence of these foreign substances upon the raw milk quality evaluation using Fourier-transform infrared spectroscopy (FTIR) and flow cytometry methods. The objective of this work was to analyze the raw milk composition readings obtained by FTIR spectroscopy. Raw milk was adulterated with formaldehyde (25; 50; 100 ppm), hydrogen peroxide (100; 500; 1000 ppm) and sodium bicarbonate (300; 500; 1000 ppm) in vials containing bronopol as preservative, and stored at 2 temperatures (7°C and 25°C). Components (fat, protein, lactose, total solids, solids nonfat, MUN and SCC analyses; CombiScope FTIR, Delta Instruments), and total bacteria counting (TBC) (BactoScan FC, Foss Electric) were performed after storage (0, 3, 24, 48, 72, and 168 h). Multiple linear regression model was used for statistical analysis. The addition of these adulterants resulted in significant changes (P ≤ 0.05) for all dependent variables. Formaldehyde addition resulted in slightly increased readings for all components, except for casein, SCC, TBC and freezing point, which decreased. Hydrogen peroxide addition resulted in higher results for evaluated milk parameters, except for lactose, casein, SCC and TBC, which decreased. Finally, sodium bicarbonate addition slightly increased fat, protein, lactose, TS, SNF, TBC and decreased casein, MUN, SCC, and freezing point results. These alterations were more impacting for MUN and TBC. It is concluded that components analyzed by FTIR method may be affected by foreign substances illegally added to the raw milk. However, through chemometric techniques, these abnormal spectrum readings have the potential to be used for FTIR monitoring of milk adulteration.