A Comprehensive Review of Photooxidation Browning in Food Systems: Substrates, Mechanisms, Effects, and Inhibition...

The color of food plays a crucial role in purchasing decisions, as consumers frequently associate its appearance with quality. Browning reactions often damage food color, reducing visual appeal and consumer acceptance. Currently, comprehensive understanding has focused on enzymatic browning and nonenzymatic Maillard reactions, whereas complex photooxidation browning (POB) remains inadequately and systematically understood. This review systematically examines the mechanism of POB and its impact on food quality by synthesizing existing literature. We comprehensively analyze the substrates involved, reaction mechanisms, and key influencing factors in POB. Furthermore, we present an updated overview of current inhibition strategies and propose preventive measures to mitigate the POB of food products. POB involves a variety of chemical substrates, including but not limited to nitrogen-containing compounds, polyphenolic compounds, unsaturated lipids, and phytosterols. These substrates primarily undergo POB through three pathways: singlet oxygen-mediated oxidation, free radical chain reactions, and direct photolysis. However, reaction conditions-including light intensity, wavelength, oxygen concentration, photosensitizers, temperature, pH, and packaging materials-significantly impact POB. With these factors in mind, proposed strategies include dynamic light wavelength adjustment, modified atmosphere packaging, antioxidants incorporation, light-blocking materials, nanotechnology applications, and multilayer barrier films with nonmigratory active components. Not only does this review provide readers with a comprehensive understanding of POB, but it also offers actionable directions for future research, which is of vital importance to deal with the increasingly significant impact of light in the food industry.