Inspection of antimicrobial particles in milk using RGB-laser scattering imaging combined with chemometric procedures

Abstract

The immobilisation of phytochemicals on inert particles has demonstrated high potential to develop new formulations of natural antimicrobials for preserving liquid foods such as milk. This work aimed to test the capability of the laser scattering imaging technique combined with chemometric procedures to inspect antimicrobial particles in milk matrices non-destructively. The RGB laser's interactions with the milk matrix were captured as diffraction patterns in digital images, from which data were extracted after imaging processing and modelled by chemometric procedures. The antimicrobials were based on solid inorganic particles (silica) functionalised with a plant essential oil (eugenol). The effect of the natural variability from five types of milk was studied (cow 0, 1.5 and 3.5% lipids, goat and sheep). The inspection functions focused on predicting the type of milk, presence of antimicrobial particles, functionalisation of particles and type of inorganic structure. PLS-DA was applied to perform classification models for each property prediction, combined with pre-processing and variable selection procedures to isolate the variability of the property of interest. The results revealed a high classification capacity for milk types. The properties of antimicrobials were also successfully predicted. In this case, data pre-processing and variable selection procedures had to be applied to reduce structural noise and improve the models from raw data. Combining imaging and chemometrics techniques could capture and model the variability generated by antimicrobial particles independently of the nature of milk. It established the basis for developing a possible non-destructive inspection system to control liquid food containing these new antimicrobials.