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Background Polymer hydrogels have attracted considerable attention as functional materials. The conventional single network hydrogels (SNs) are mechanically either too soft or brittle to be used as load-bearing substances. Therefore, the interpenetrating network hydrogels (IPNs) with unique physical characteristics paid more and more attention and they have shown great potentials in fabricating a variety of food structures with desired functionalities. Scope and approach This review provided a summary of the latest developments and applications of IPNs in terms of synthesis strategies (heating-cooling, enzymatic, and ionic-induced technique), physical performance (mechanical property, water holding capacity, swelling capacity, and thermal property), formation and strengthening mechanisms, as well as food applications. The major future trends of IPNs in food systems were also discussed. Key findings and conclusions As compared with SNs, IPNs generally exhibited more favorable mechanical performance, water holding capacity and thermal stability. The strengthening mechanisms of IPNs were mainly attributed to the filling of polysaccharides in other biopolymers, the increased density of entangled network, and the possible interactions between individual networks. IPNs with tunable mechanical property could be fabricated, showing great potential for various food applications such as edible films, three-dimensional printing, delivery of bioactive/aroma compounds, as well as fat replacers.

Optimized AR/FGA DNs exhibit excellent mechanical performance and comparable texture with beef tendons.

The antioxidant and immunomodulatory activities of selenium-enriched rice protein hydrolysates (Se-PH) were evaluated by a cellular antioxidant activity test and macrophage proliferation and phagocytosis assays, respectively. The results showed that trypsin hydrolysate provided the highest proliferation rate of 60.91% at a concentration of 100 μg/mL. Moreover, a remarkable rise in the phagocytosis rates for trypsin hydrolysate (64.1%) and pepsin-trypsin hydrolysate (54.5%) was observed when the sample concentrations were increased to 50 μg/mL. A positive correlation was found between the phagocytic ability of macrophages and both the selenium concentration and the degree of hydrolysis of Se-PH, and the correlation coefficients R obtained were 0.792 and 0.930 (P < 0.05), respectively. The capacity of Se-PH to inhibit the oxidation of dichlorodihydrofluorescein had a significant negative correlation with the phagocytic ability of macrophages (R = -0.840, P < 0.05). In conclusion, a positive correlation was found between the antioxidant activity and the immunomodulatory activity of Se-PH, which could be used as potential functional food additives for improving human health.

Shellfish consumption is an important pathway for coastal residents exposure to inorganic arsenic (iAs) and methylmercury (MeHg). An integrated method had been developed for simultaneous determination of iAs and MeHg in shellfish with microwave-assisted extraction and high performance liquid chromatography-inductively coupled plasma mass spectrometry identification. The limits of detection were 0.0520, 0.1003 and 0.0015 mg/kg (dry weight) for AsIII, AsV and MeHg, respectively. The proposed method was applied to evaluate the contents and health risks of iAs and MeHg in shellfish from the typical coastal cities (Lianyungang and Yantai) in China. The concentrations of iAs and MeHg in fresh shellfish were 0.10–1.69 mg/kg and 0.46–6.38 μg/kg, respectively. The target hazard quotient and target cancer risk values of iAs were the highest for the children and adults in Lianyungang, and were respectively larger than 1 and 1 × 10−4, indicating both non-carcinogenic and carcinogenic risks of iAs exposure were significant in this area.