Bioactives can impact food function either by their dosage or by their forms of dispersion, though the latter remains mostly neglected. Here we report the incidental nanoparticles (iNPs) carrying hepatoprotective bioactives identified in freshwater clam (Corbicula fluminea Muller) soup, which is a folk remedy for liver conditions in East Asia. The soup was fractionated into two iNPs containing fractions with high yield (95.8%) in 35 min by gel chromatography. With hydrodynamic diameter (Dh) range from 40 nm to 149 nm, iNPs were mainly constituted by carbohydrates and proteins. Notably, the majority of bioactives, e.g. taurine (63.2%), ornithine (68.1%) and phytosterols (60.0%), was determined to be carried by the iNPs. It suggested a possible mechanism of elevated delivery and absorption of bioactives, explaining why the clam soup can work at the bioactive concentrations way lower than the individual compound. These iNPs have great potential to be developed into a functional food with most potent nutraceutical effects.

Abundant nanostructures have been constantly found in various foods, like vinegar, tea, coffee, and milk. However, these structures largely remain unexplored and even been eliminated for stability reasons in food industry. Here we report the isolation, characterization, and antioxidant activities of food nanoparticles (NPs) carrying polyphenols from Chinese rice vinegar. Using a gel-chromatography-based isolation protocol, the vinegar was separated into three major fractions. They were identified as spherical NPs (P1), lollipop-like NPs (P2) and spherical microparticles (P3) with average hydrodynamic diameter of 210, 245,1643 nm, separately. The former two fractions accounted for the major parts of dry matter in the vinegar. The P1-NPs fraction was composed of proteins, carbohydrates, and a high number of polyphenols (15 wt%), demonstrated potent antioxidant activity as determined by ABTS and ORAC assays. Moreover, they effectively quenched peroxyl free radicals in peritoneal macrophages and promoted cellular growth. The P2 fraction contained majority of organic acids, esters and mineral elements of the vinegar. It demonstrated the NPs are bioactive units of the rice vinegar, inspiring the development of novel functional nanomaterials with nutraceutical and pharmaceutical applications.

How to maintain the physicochemical stability of oil emulsion has been one of the major challenges in food industry. Previously we reported the demulsification effects of catalase in the fish oil emulsion. In comparison, the influences of other two metal ion-containing oxidoreductases, horseradish peroxidase (HRP) and copper/zinc superoxide dismutase (SOD), on the emulsion’s stability were investigated. Submicron fish oil-in-water emulsion stabilized by polysorbate 80 was prepared by high-speed homogenization. Its physical stability was evaluated by visual and microscopic observation, turbidity and light scattering measurements, while chemical stability by the hydroperoxide content and lipid peroxidation. HRP demulsified the emulsion in a concentration-responsive manner after 3–7 days’ incubation, resulting in a decreased turbidity and significant delamination. The enlargement of oil-polysorbate droplets and protein precipitates were confirmed by size distribution and TEM observation. HRP initially elevated the emulsion’s hydroperoxide then decreased it while raising TBARS levels during 7-Day incubation. In contrary, SOD stabilized the emulsion physically and chemically. The demulsification was correspondingly attributed to the oxidation catalyzing activity of the peroxidase and the electrostatic and hydrophobic interaction between lipids and proteins. This study adds new insight to the influences of the two oxidoreductases on the stability, lipids and peroxides of food emulsions, proposes an exciting subject of elucidating the underlying mechanism.

Maillard reaction products (MRPs) of protein, amino acids, and reducing sugars from many foods and aqueous extracts of herbs are found to have various bioactivities, including antiviral effects. A hypothesis was proposed that their antiviral activity is due to the interaction with the cellular membrane. Aiming to estimate the possible actions of MRPs on phospholipid bilayers, the Arg-Glc MRPs were prepared by boiling the pre-mixed solution of arginine and glucose for 60 min at 100°C and then examined at a series of concentrations for their effects on the phase transition of MeDOPE multilamellar vesicles (MLVs), for the first time, by using differential scanning calorimetry (DSC) and temperature-resolved small-angle X-ray scattering (SAXS). Arg-Glc MRPs inhibited the lamellar gel–liquid crystal (Lβ-Lα), lamellar liquid crystal–cubic (Lα-QII), and lamellar liquid crystal–inverted hexagonal (Lα-HII) phase transitions at low concentration (molar ratio of lipid vs. MRPs was 100:1 or 100:2), but promoted all three transitions at medium concentration (100:5). At high concentration (10:1), the MRPs exhibited inhibitory effect again. The fusion peptide from simian immunodeficiency virus (SIV) induces membrane fusion by promoting the formation of a non-lamellar phase, e.g., cubic (QII) phase, and inhibiting the transition to HII. Arg-Glc MRPs, at low concentration, stabilized the lamellar structure of SIV peptide containing lipid bilayers, but facilitated the formation of non-lamellar phases at medium concentration (100:5). The concentration-dependent activity of MRPs upon lipid phase transition indiciates a potential role in modulating some membrane-related biological events, e.g., viral membrane fusion.