The Second Life for Food Industry By-Products: From Traditional Recycling to Modern Upcycling

One of the reasons for food waste is the inefficient use of by-products. This paper presents a current overview of technological solutions for processing waste, aimed at giving it a proverbial “second life.” To this end, the most important extraction, conversion, and valorization methods are summarized and compared. Extraction using green solvents (ionic liquids, deep eutectic solvents, supercritical fluids) and green methods such as micro-wave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) are discussed. Advances in biorecycling and biotechnological methods, taking into account the role of genetically modified microorganisms (GMOs), are also described. Attention was paid to innovative approaches and current trends, such as 3D food waste printing, hybrid technologies, and the concept of smart factories involving artificial intelligence (AI), machine learning (ML), and the Internet of Things (IoT). Although all of the mentioned food waste upcycling technologies are already in use, several hurdles limit their use to their full potential. A major problem is the smooth flow of food waste to upcycling points to ensure the required quality and processing optimization. Furthermore, societal and regulatory concerns related to the use of food waste for producing value-added dietary products need to be considered.