Native starch (NS) from different botanical origins (native rice/tapioca/oat starch, NRS/NTS/NOS) were hydrophobically modified by octenyl succinic anhydride (OSA), and the octenyl succinic (OS) groups were successfully introduced in the starch molecules which obtained OS-starch (OSRS, OSTS and OSOS) with different levels of modification (0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%) and degree of substitution (DS). The structural properties of the OS-starch, such as granule size, crystal, wettability and morphology were studied, and the OS-starch was used as particulate stabilizers to produce oil-in-water (O/W) Pickering emulsions. The emulsion index, droplet size distribution and microstructures of Pickering emulsions produced by different OS-starches were compared. OSA modification had almost no effect on the morphology or crystal structure types of three kinds of NS and OS-starch but markedly increased the contact angle and particle size distribution of OSRS, OSTS and OSOS. Esterification reaction of OSA and starch mainly occurred in amorphous regions of starch, and the OSA significantly improved the emulsifying capacity of OSRS, OSTS and OSOS granules and thus stabilized emulsions formed at higher levels (2.5% and 3.0%) of modification of OS-Starch exhibited better stability; the ability of OS-starch to stabilize Pickering emulsion was 3.0% OSRS > 3.0% OSOS > 3.0% OSTS, respectively. Observation and structural properties analysis of OS-starch granules and Pickering emulsion droplets showed that the number and thickness of the starch granules on the oil-water interface of the emulsion droplets increased with improvement of the OSA modification level, and an aggregation state was formed between the OS-starch granules, which was also enhanced with the OSA modification levels. These were all necessary for the Pickering emulsion stabilized by starch granules to remain in a steady state.

The influence of epigallocatechin gallate (EGCG) on the physicochemical–rheological properties of silver carp surimi gel was investigated. The gel strength, texture, water-holding capacity (WHC), dynamic distribution of water, and rheological properties of surimi gels added with different levels (0, 0.02, 0.04, 0.06, 0.08, and 0.1%) of EGCG were measured. The results showed that with the increase of EGCG content, the gel strength, hardness, WHC, and immobilized water contents of surimi gels showed a trend of first increasing and then decreasing, and EGCG 0.02% and EGCG 0.04% showed better gel performance as compared with the control. EGCG 0.02% had the highest gel strength (406.62 g·cm), hardness (356.67 g), WHC (64.37%), and immobilized water contents (98.958%). The gel performance decreased significantly when the amounts of EGCG were higher than 0.06%. The viscosity, G′, and G″ of the rheological properties also showed the same trends. The chemical interaction of surimi gels, secondary structure of myofibrillar protein (MP), and molecular docking results of EGCG and silver carp myosin showed that EGCG mainly affected the structure and aggregation behavior of silver carp myosin through non-covalent interactions such as those of hydrogen bonds, hydrophobic interactions, and electrostatic interactions. The microstructures of EGCG 0.02% and EGCG 0.04% were compact and homogeneous, and had better gel formation ability. The lower concentrations of EGCG formed a large number of chemical interactions such as those of disulfide bonds and hydrophobic interactions inside the surimi gels by proper cross-linking with MP, and also increased the ordered β-sheet structure of MP, which facilitated the formation of the compact three-dimensional network gel.

Intelligent food packaging (IFP) is among the key technologies for overcoming global challenges of food safety and food resource waste. Its core lies in monitoring the quality of food in real-time without damage. Sodium alginate (SA), a natural polysaccharide characterized by biodegradability and excellent biocompatibility, can form hydrogels with a 3D network structure, high water content, and functional modification capability, making it an ideal matrix for developing IFP sensing and indicator platforms. Based on the gel chemistry fundamentals of SA, this paper deeply analyzes the structure-activity relationship between sensing mechanism and material structure, and summarizes the existing modification strategies and functional integration paths. The paper also provides a detailed discussion on the application principles and latest advancements of SA-based hydrogels in colorimetric/visual sensing, gas sensing, time-temperature indicator (TTI), and controlled-release carriers for active substances. The current research results show that the detection limit of SA hydrogel beads loaded with anthocyanins for volatile amines can reach 15–25 ppm, and the color difference ΔE can reach 34.2 after 7 days of storage at 4 °C, which is strongly correlated with microbial indicators, total volatile basic nitrogen (TVB-N), pH, etc. The color difference value (ΔE) response of Co-Imd microcrystalline functionalized SA film to ammonia gas reached 23.7 within 60 min, and it had antibacterial activity. The activation energy of Immobilization of laccase on sodium alginate/soluble starch microcapsules to develop a TTI (27.32–61.13 kJ/mol) was highly matched with the activation energy of Agaricus bisporus. The hydrogel microspheres loaded with Cur@Se reduced the total oxidation value of the oils by 53%. The G/SA/nZnOs cryogel pad extended the shelf life of shrimp from 4 days to 6 days at 4 °C. In addition, this paper also discusses the challenges faced by SA-based hydrogels in large-scale production and long-term stability evaluation, and looks forward to future development trends such as integration with artificial intelligence (AI), Internet of Things (IoT), and multi-functional integration, in order to provide theoretical support for in-depth research and industrial application in this field.