No abstract

Myofibrillar protein (MFP) of Japanese seerfish (JS) was oxidized by Fenton system (1, 4, 8, 16 mM H2O2 for 0, 2, 4, 6 hr). After oxidation, α‐helix ratio and sulfhydryl content of MFP declined along with the increased carbonyl and dityrosine levels. Bromophenol blue bound in MFP under 1 mM H2O2 slightly increased. Polymers together with attenuated myosin heavy chain in protein pattern were observed. Compared with non‐oxidized MFP, storage modulus (G′) of MFP subjected to 1 mM H2O2 for 4 hr increased while that of MFP exposed to 16 mM H2O2 declined. When treated with microbial transglutaminase (MTG), mildly oxidized (1 mM H2O2, 2 hr) MFP showed higher G′ while heavily oxidized (16 mM H2O2, 2 hr) MFP had lower G′ than control. Oxidation showed pronounced influences on physiochemical and gelling properties of JS MFP and the oxidation extent affected MTG role on it. Practical applications Protein oxidation occurs extensively in muscle and exerts great influences on muscle food quality. JS is widely used for producing gel food in China. Its muscle also contains oxidation initiators such as H2O2, hemoglobin and lipids, increasing the susceptibility to protein oxidation. Results of the study exposed the effects of hydroxyl radical oxidation on physiochemical and gelling properties of JS MFP. It provides strategic support to improve gel properties of MFP by manipulating oxidation.

Astaxanthin (AST), a fat-soluble carotenoid, shows excellent antioxidant and anti-inflammatory activities, but its low biocompatibility and stability limit its application in the food industry. In this work, we constructed the targeted hyaluronic acid (HA)-modified milk exosome-based astaxanthin delivery system to improve the biocompatibility stability and targeted transport properties of astaxanthin. Nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR) showed that HA was efficiently modified onto the surface of the milk exosome by an amide condensation reaction. The fluorescence images showed that the targeted delivery system accumulated in RAW264.7 macrophages, and the targeting effect on inflammatory cells was significantly enhanced. Compared with free astaxanthin, the delivery system could enhance the cellular uptake of astaxanthin and alleviate the overproduction of reactive oxygen species significantly and the depolarization of mitochondrial membrane potential in a lipopolysaccharide-induced cellular model. The delivery system also notably inhibited the expression of IL-1β, IL-6, and other inflammatory factors. Therefore, the targeted hyaluronic acid-modified milk exosome-based astaxanthin delivery system prevents the activation of macrophages and the production of inflammatory mediators and has the potential to apply to the prevention of chronic inflammatory diseases.

Nanocarriers provide the possibility to overcome the low solubility, poor stability, and low bioavailability of functional factors. However, most nanocarriers do not directly participate in the corresponding effects of functional...