In this study, soluble dietary fiber (SDF) and insoluble dietary fiber (IDF) were extracted from Pyrus ussuriensis Maxim pomace via three methods including enzymic extraction (EE), microwave-assisted enzymatic extraction (MEE), and three-phase partitioning (TPP). The effects of different extraction methods on the structure, physicochemical property, and functional activity of the extracted dietary fiber were evaluated. The results showed that different extraction methods had significant effects on the extraction yield, molecular weight distribution, thermal stability, antioxidant activity, and hypoglycemic activity in vitro, but resulted in no difference in the structure and composition of functional groups. It is noteworthy that SDF extracted by TPP has a more complex and porous structure, lower molecular weight, and higher thermal stability, as well as better physicochemical properties and in vitro hypoglycemic activity. IDF extracted by MEE showed the greatest water and oil holding capacity; the highest adsorption capacity for glucose, cholesterol, and nitrite ion; as well as the strongest inhibitory activity on α-amylase. These results suggest that PUP may be a source of cheap natural dietary fiber.

Shigella dysenteriae is a highly pathogenic microorganism that can cause human bacillary dysentery by contaminating food and drinking water. This study investigated the antibacterial activity of chestnut bur polyphenol extract (CBPE) on S. dysenteriae and the underlying mechanism. The results showed that the minimum inhibitory concentration (MIC) of CBPE for S. dysenteriae was 0.4 mg/mL, and the minimum bactericidal concentration (MBC) was 1.6 mg/mL. CBPE treatment irreversibly disrupted cell morphology, decreased cell activity, and increased cell membrane permeability, cell membrane depolarization, and cell content leakage of S. dysenteriae, indicating that CBPE has obvious destructive effects on the cell membrane and cell wall of S. dysenteriae. Combined transcriptomic and metabolomics analysis revealed that CBPE inhibits S. dysenteriae by interfering with ABC protein transport, sulfur metabolism, purine metabolism, amino acid metabolism, glycerophospholipid metabolism, and some other pathways. These findings provide a theoretical basis for the prevention and treatment of S. dysenteriae infection with extract from chestnut burs.

To investigated the effect of exogenous selenium on selenium enrichment and antioxidant activity of germinated chestnut. We treated ‘Zaofeng’ chestnuts with 0, 20, 40, 60 and 80 mg/L concentration of Na₂SeO₃, and the analyses focused on total Se, SeCys₂, MeSecys, Se^IV, SeMet, Se^VI, γ -aminobutyric acid (GABA), antioxidant enzyme (PAL, SOD, GPX, CAT) activity, non-enzymatic antioxidant substances (total polyphenols and flavonoids) content and antioxidant capacity (DPPH, ABTS) during germination. The results indicated that low concentration of selenium (20-40 mg/L) significantly promoted the organic transformation of selenium, increased antioxidant enzyme activity and phenol accumulation, and enhanced antioxidant capacity of chestnut. High concentration of selenium (80 mg/L) induced oxidative stress, inhibited enzyme activity and reduces antioxidant capacity of chestnut. During the germination of chestnut, selenite was absorbed by embryo and subsequently transformed into organic Se in vivo, ultimately being stored in the form of SeCys₂. The selenium enrichment rate decreased significantly with the increase of Na₂SeO₃ treatment concentration. Furthermore, the treatment with 40 mg/L Na₂SeO₃ led to a significant increase in GABA content of germinated chestnut. Overall, 20-40 mg/L Na₂SeO₃ were identified as the suitable concentration for germinated chestnut. This study provides a theoretical basis for developing functional food of selenium-enriched germinated chestnut.

The objective of this study was to investigate the effect of exogenous selenium on selenium enrichment and antioxidant activity of germinated chestnuts. We treated ‘Zaofeng’ chestnuts with Na₂SeO₃ at concentration of 0, 20, 40, 60 and 80 mg/L, and analyzed, during germination, the level of total Se, SeCys₂, MeSecys, Se^IV, SeMet, Se^VI, γ-aminobutyric acid (GABA), antioxidant enzyme (phenylalanine ammonialyase (PAL), glutathione peroxidase (GPX), superoxide dismutase (SOD) and catalase (CAT)) activity, non-enzymatic antioxidant substances (total polyphenols and flavonoids) content and antioxidant capacity (DPPH, ABTS). The results indicated that low concentrations of selenium (20–40 mg/L) significantly promoted the organic transformation of selenium, with a Se-enrichment rate over 74%. Antioxidant enzyme (PAL, SOD, CAT) activities and total phenol content were enhanced by 1.1 to 1.9-fold compared with the control, leading to a 12.2–29.2% improvement in antioxidant capacity (DPPH and ABTS). In contrast, the high concentration of selenium (80 mg/L) induced oxidative stress, inhibiting enzyme (PAL, SOD, CAT) activities (reduced by 14.1–20.5%) and decreasing antioxidant capacity (DPPH) by approximately 19.0%. During chestnut germination, selenite was absorbed by the embryo and subsequently transformed into organic Se in vivo, ultimately being stored mainly as SeCys₂. The selenium enrichment rate decreased significantly with increasing Na₂SeO₃ treatment concentration: from 86.4% at 20 mg/L to 62.2% at 80 mg/L. Furthermore, treatment with 40 mg/L Na₂SeO₃ led to a significant increase in GABA content of germinated chestnuts, reaching 1.3 times that of the control group. Overall, germination with 20–40 mg/L Na₂SeO₃ is an effective condition for producing Se-enriched chestnut sprouts with enhanced GABA and antioxidant capacity, offering a potential functional food ingredient.