Evaluation of Photo-oxidation in Full-Fat Milk under Different Light Spectra: A Laboratory Experiment in Food Chemistry

Photo-oxidation is one of the main causes of oxidative deterioration in food. Understanding of the mechanisms of photo-oxidation is essential for food science students when pursuing careers in food safety and quality assurance. However, few food chemistry laboratories emphasize photo-oxidation. Thus, we develop a laboratory activity that trains students to evaluate the level of photo-oxidation by monitoring the early (photosensitizer), middle (dissolved oxygen), and late [thiobarbituric acid reactive substances (TBARS) value] indicators of photo-oxidation in a full-fat milk model under two types of light spectra (fluorescent and LED light). Through data analysis and post-laboratory discussion, students well understood the mechanism of photo-oxidation and the effect of light wavelength on the rate of reaction in food products by characterizing the oxidation kinetics at different stages of oxidation. This laboratory was designed for upper-level undergraduate students of food science and technology majors (n = 30), the learning outcome shows that students acquire practical skills in operating instruments that they may encounter in food industry as well as quantitative analytical methods that are used to estimate the shelf life of food products.