Recent advances in optical sensors and probes for the detection of freshness in food samples: A comprehensive review (2020–2023)

With the continuous expansion of the global population, securing adequate high-quality food suppliers has become paramount. The process of food spoilage not only produces considerable food waste but also has negative effects on the human body.Therefore, developing effective real-time methods for monitoring food freshness is crucial. This article categorizes and discusses the current state of development of optical sensors using natural colorants, small fluorescent probes, and nanosensing materials between 2020 and 2023. The article also reviews the strengths and weaknesses of these detection methodologies and provides a summary of the current research on the fabrication of portable devices. Emerging technologies related to monitoring of food freshness, such as intelligent device-based detection methods, functionally integrated smart packaging, and sensing arrays, are also discussed. Finally, this article highlights the existing research gaps and proposes directions for future research in food-freshness detection.