Valorization of food wastes by implementation of subcritical water extraction: A comprehensive review

Background: Every year, almost 1.6 billion tonnes of food are wasted, with 54 % going to waste during production and 46 % going to waste during post-market operations. The majority of this waste consists of seeds, skin, rind, and pomace, and it is full of bioactive compounds like carotenoids, polyphenols, dietary fibers, vitamins, enzymes, and oils. These valuable compounds can be extracted using a variety of techniques, which will promote sustainable development. The nutritional profile of other food items can be improved by incorporating these bioextract compounds in the food products. Scope and strategy: The efficiency and waste generated by organic reagents are just two drawbacks of traditional extraction techniques. Alternatives that are more effective include novel methods like ultrasound-, microwave-, and ultrahigh pressure-assisted extraction. Another novel eco-friendly technique, subcritical water extraction (SWE), is growing popularity due to its safety and favorable effects on environment. It can modify the polarity and dielectric constant of solvents, under high temperature and pressure. This improves the extraction process, increases the mass transfer efficiency of the extracts, and maintains the biological activities of the extracts, all of which have a wide range of potential applications. Key findings and conclusion: SWE is a sustainable and energy-effective way of food processing because it catalyzes chemical reactions that convert polysaccharides into valuable chemicals. Oils, lignans, proteins, and carbohydrates have all been used to extract valuable components from diverse agricultural and agro-industrial waste. Also, by-products originating from food processing activities encompass a wealth of nutritional, functional, and bioactive elements. These resources hold great potential for the creation of novel food products, waste reduction, and enhancing the overall sustainability of our food systems. This review article discusses about the sustainable extraction of useful components from food waste byproducts using SWE that is a promising technology that helps more efficiently also produces less waste.