Analysis of Component Composition of Highly Scattering Media Using a Fluorescence˗Scatterometry Method

Optical diagnostic methods are widely used in studying dispersed media. However, analyzing these media is challenging due to their complex composition, opacity, or state of motion, rendering traditional methods like spectrophotometry unsuitable without pre˗processing. In food safety, optical methods offer non˗invasive analysis of products, maintaining their quality. Milk, a complex, multi˗component medium, particularly requires component diagnostics. Scatterometry and scatterometry˗based methods are a promising alternative for the analysis of turbid polydisperse media, providing sufficiently high accuracy, flexibility, and the possibility of creating economical and compact devices, in contrast to large and expensive laboratory equipment, such as spectrophotometric devices. This is particularly important for early quality control, as it allows for the identification of milk with signs of animal diseases, such as somatic cells, reducing costs for both large producers and small farms. A novel fluorescence˗scatterometry method for component diagnostics of milk is proposed for the first time, allowing for sufficiently accurate determination of fat, protein, and somatic cell content in both static and dynamic states. A relationship was established between the laser light scattering indicatrix and fat content. It was found that somatic cells distort the indicatrix only in forward scattering, which allows for their determination without significantly affecting fat content measurements. It is shown that the percentage of protein content can be determined from fluorescence, taking into account the previously determined fat content. The results were confirmed by modeling and implemented in a prototype flow˗through device capable of measuring the content of fat, protein, and somatic cells in a moving gas˗milk mixture. This approach offers a fast, reliable, and cost˗effective method for milk analysis.

laser light scattering, fluorescence, scatterometry, fluorimetry, optical sensors, milk quality control