Hydrogels are tri-dimensional, hydrophilic polymer networks that can absorb and retain significant amounts of water. Often referred to as the “intermediate aqueous phase,” hydrogels exhibit a unique balance of elastic and viscous properties, positioning them between solid and liquid phases (Guo et al., 2021). It has gained prominent attention in the agriculture, medicine, food, and pharmaceutical industries (Klein & Poverenov, 2020). Based on the network structures, hydrogels can be categorized into two primary types: physical and chemical gels. Chemical gels (or true gels) are stabilized by covalent interactions, offering permanent and structurally robust networks, while physical gels (or pseudo gels) derive stability from weaker interactions, such as electrostatic forces, chain entanglements, hydrogen bonding, or hydrophobic forces. Due to this, physical gels are reversible and temperature-responsive, transitioning into polymer solutions upon heating (Raza et al., 2021). A third category, dual-network hydrogels, is formed by combining physical and chemical methods, thereby enhancing functionality. Furthermore, hydrogels can be classified based on the source, ionic charge, preparation methods, physical properties, responsiveness, and degradability (Jinlong et al., 2021). Fig. 1 provides a classification of the hydrogels.

Polysaccharides and proteins are natural sources widely used in hydrogel fabrication for food applications. These natural polymers are particularly effective in enhancing food texture and organoleptic properties by functioning as gelling agents, stabilizers, and emulsifiers (Le et al., 2017; McClements, 2017). The high water absorption capacity, due to hydrophilic pendant groups, along with excellent swelling properties resulting from the elastic nature of polymer chains, makes them ideal for applications in food industries (Bashir et al., 2020). These functional attributes open up diverse applications, including biodegradable packaging, food preservation, delivery systems, animal food analogues (e.g., fat mimetics), water treatment, filters, and absorbents (Manzoor et al., 2022). Furthermore, bio-hydrogels are increasingly employed in hazard detection, where their flexible porous structure and high loading capacity enable effective signal trapping and improved anti-interfacial performance in sensing applications (Jun et al., 2021).

While natural hydrogels offer distinct advantages such as biocompatibility and biodegradability, synthetic hydrogels, derived from petroleum-based products like polyacrylamide, polylactic acid, and polyacrylic acid, provide physical and chemical stability. These synthetic polymers are particularly valued for hydrophobicity and are used in food packaging applications, where durability is required (Sudheer et al., 2023). Nonetheless, natural polymer-based hydrogels are increasingly gaining attention due to their abundance, exceptional biocompatibility, and environmentally friendly biodegradability, which set them apart from synthetic alternatives. (Klein & Poverenov, 2020).

Hydrogel fabrication techniques vary depending on the desired properties and applications. Conventional methods include physical and chemical crosslinking, polymerization grafting, and ionic crosslinking, which often require the use of heat, chemicals, enzymes, and pH changes to facilitate polymer network formation. However, these techniques often face challenges such as high energy consumption, lengthy processing times, and safety concerns (Larrea-Wachtendorff et al., 2021; Yan et al., 2024). To overcome these limitations, researchers are increasingly exploring advanced technologies for hydrogel fabrication, including high-pressure processing, ultrasound, cold plasma, moderate electric field, and ionizing radiation techniques. These innovative approaches offer the potential for more efficient and safer hydrogel fabrication, paving the way for expanded use in food industries (Hao et al., 2015; More & Chapekar, 2024; Pérez-Huertas et al., 2024). This review highlights the different sources and fabrication methods for hydrogels, with a particular emphasis on the integration of emerging technologies to develop hydrogels that can be tailored for specific applications, particularly in the food sector.