The nature and interaction of the constituent substances that make up the sour-milk dessert with plant-based fillers have been studied by the method of IR spectroscopy. This method is used to study the diverse nature of substances. The spectral range applied was in the range of 500–4,000 s -1. It was found that the intensity of functional groups absorption in the range of 2,500–3,500 s-1 is due to the valence vibrations of NH-, CH and S-H-groups, indicating the presence of free organic acids, aromatic substances. In addition, in the spectra of sour-milk dessert with plant-based fillers, an absorption intensity in the range of 1,470–1,335 s-1 is observed, which indicates the presence of soluble pectin. Proteins characteristics in the samples are observed at absorption in the range of 3,300–3,500 cm-1, which is due to the valence vibrations of the N-H bond in the -NH2 groups
