Near‐infrared spectroscopy for compositional analysis of raw milk: Challenges and opportunities

Background Raw milk is the starting ingredient of all dairy products. Understanding the quality and composition of raw milk is essential for ensuring efficient dairy processing and manufacturing final products of consistent quality. Near‐infrared (NIR) spectroscopy has been used in the dairy industry for the compositional analysis of several dairy products due to its low cost, minimal sample preparation, straightforward instrumentation and potential for inline measurement. However, measuring the composition of raw milk using NIR spectroscopy continues to remain a significant challenge. Aims The review examines the measurement principles, advantages and limitations of NIR spectroscopy for the compositional analysis of raw milk. It also highlights the challenges and potential limitations of the technique under various measurement settings, including offline, online, inline and in‐field. Methods A systematic review of the literature on compositional analysis of raw milk components using NIR spectroscopy in various measurement settings was conducted. The review also evaluates the performance of miniaturised NIR sensors and emerging analytical approaches for compositional analysis of raw milk. Major Findings NIR spectroscopy demonstrates high accuracy for quantifying macrocomponents of raw milk, such as fat, protein and lactose, particularly in laboratory settings. The miniaturised NIR sensors show promising results for fat and protein; however, their applicability for in‐field measurement requires further validation. Challenges remain in measuring microcomponents and particle size distribution due to strong water absorption bands that obscure certain spectral features. Further improvement in NIR instrument design is required for their applicability in in‐line measurement. Industrial Implications The inline compositional analysis of raw milk using NIR spectroscopy can transform the dairy industry by enabling real‐time raw milk quality assessment, which helps improve process understanding and optimisation. Further research in miniaturised spectrometers, robust calibration techniques and microcomponent measurement is essential to facilitate the uptake and adoption of NIR spectroscopy in dairy processing.