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To explore the extraction process, structural characterization and in vitro antioxidant activity of alcohol soluble proteins from ginseng. This study used ginseng as the research object, explored the optimal extraction process of ginseng alcohol soluble protein by one-way test and response surface test, structurally characterized ginseng alcohol soluble protein by ultraviolet absorption spectrometry, infrared spectrophotometric analysis, amino acid composition, and microstructure observation, and carried out a series of studies on its antioxidant activity in vitro under different pH conditions. The in vitro antioxidant activity of ginseng alcohol soluble protein was evaluated by determining the DPPH radical scavenging capacity, ·OH scavenging capacity, and iron ion reduction capacity. The results showed that the optimal extraction process of ginseng alcohol soluble protein was 2 h, extraction material-liquid ratio of 1:10 g/mL, and extraction pH of 7, at which the yield of ginseng alcohol soluble protein was 0.319% and the protein content was 75%. The results of ultraviolet spectrophotometry, infrared spectrophotometry and amino acid composition analysis showed that the total amount of amino acids in ginseng alcohol soluble protein was 82.3 g/100 g, of which the content of essential amino acids was 26.46 g/100 g, and the content of medicinal amino acids was 30.51 g/100 g, which verified that the main component of ginseng alcohol extract was indeed protein, and the molecular weight was about 3.3 kDa. The SEM results showed that the ginseng alcoholic protein was structurally complete, the surface was sparse with irregular ridges and a small number of pores, and the protein particles showed honeycomb aggregation with a stable and orderly reticular structure. The results of in vitro antioxidant test showed that the protein had strong in vitro antioxidant activity under strong acidic conditions. When the pH was 1, the scavenging rate of ginseng alcohol soluble protein for DPPH radical was 96%, the scavenging rate for ·OH was 79%, and the reducing ability for iron ion was 0.86.

[Display omitted] • The curcumin-loaded composite nanoparticles based on high-hydrostatic-pressure-treated (HHP-treated) zein and pectin at 150 MPa were prepared. • HHP-treated zein exposed more hydrophobic binding sites with high affinity to better encapsulate curcumin. • The interaction force among HHP-treated zein, pectin, and curcumin in composite nanoparticles was enhanced to form a tighter and more stable structure. • The composite nanoparticles enhanced the photostability and thermal stability of curcumin. • The composite nanoparticles enhanced the bioaccessibility of curcumin. We successfully designed curcumin (Cur)-loaded composite nanoparticles consisting of high-hydrostatic-pressure-treated (HHP-treated) zein and pectin with a pressure of 150 MPa (zein-150 MPa-P-Cur), showing nano-spherical structure with high zeta-potential (−36.72 ± 1.14 mV) and encapsulation efficiency (95.64 ± 1.23 %). We investigated the interaction mechanism of the components in zein-150 MPa-P-Cur using fluorescence spectroscopy, molecular dynamics simulation, Fourier-transform infrared spectrometry and scanning electron microscopy techniques. Compared with zein-P-Cur, the binding sites and binding energy (−53.68 kcal/mol vs. − 44.22 kcal/mol) of HHP-treated zein and Cur were increased. Meanwhile, the interaction force among HHP-treated zein, pectin, and Cur was significantly enhanced, which formed a tighter and more stable particle structure to further improve package performance. Additionally, Cur showed the best chemical stability in zein-150 MPa-P-Cur. And the bioavailability of Cur was increased to 65.53 ± 1.70 %. Collectively, composite nanoparticles based on HHP-treated zein and pectin could be used as a promising Cur delivery system. [ABSTRACT FROM AUTHOR]