Portable optical instrument for detection and quantification of milk adulteration: A study on mixtures from different species and water dilution

This study addresses the need to detect and quantify milk adulteration resulting from mixtures of different species (goat, cow, and sheep) to prevent fraud in the dairy sector. The complexity arises from the need to recognize and measure multiple components considering that each type of milk has a unique chemical composition. Optical spectroscopy techniques, coupled with a highly precise portable instrument, were employed for this purpose. Our investigation encompassed adulteration arising from the mixture of milk from different species (cow, goat, and sheep), as well as dilution of cow's milk with water. The study's scope was broadened to include milk with diverse heat treatments, fat content, and commercial brands. Discriminant analyses provided reliable predictive models, with Accuracy and Cohen's Kappa values ranging between 0.80 and 1. In the quantitative studies, the quantification of milk mixtures at a minimum percentage interval of 10% was detected with Mean Absolute Error (MAE) values between 0.14 and 0.05, and 0.03 for cow's milk adulterated with water at adulteration levels of 5%. The portability of these instruments adds a significant advantage by enabling on-site and real-time determination and quantification of adulteration, thereby enhancing efficiency and responsiveness in detecting food fraud, while safeguarding product quality and nutritional benefits.