The molecular mechanism of the interaction between resveratrol and trypsin was studied using fluorescence spectroscopy (intrinsic fluorescence, synchronous fluorescence, three-dimensional fluorescence), ultraviolet-visible (UV-vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy and the molecular docking method, as well as through enzyme activity and antioxidant assay. The fluorescence experiments (the Stern–Volmer quenching constants (K_SV)) indicated that resveratrol quenched the intrinsic fluorescence of trypsin through the static quenching mechanism. The number of binding sites was about one. The thermodynamic functions ΔG < 0 and ΔH > 0, ΔS > 0 of the binding process, indicating that the combination of the resveratrol and trypsin processes was a spontaneous exothermic reaction and that the hydrophobic effect was the main force between them. UV-vis spectra, synchronous fluorescence spectra and three-dimensional fluorescence spectra analysis showed that the combination of resveratrol and trypsin induced changes in the microenvironment around the fluorophores of trypsin, resulting in alterations in the spatial structure of trypsin. FT-IR spectroscopy indicated that the contents of the α-helixes and β-turns in trypsin decreased and that the contents of the β-sheets, random coils and antiparallel β-sheets increased. All these experimental results were verified and reasonably explained by the molecular docking results. Upon resveratrol and trypsin binding, the enzyme catalytic activity of trypsin and the antioxidant of resveratrol decreased. Results from this study would be useful in elucidating the molecular mechanisms of the interactions between resveratrol and trypsin and contribute to making full use of resveratrol in the food industry.

Dehydration can significantly extend the shelf life of dried carrots and still retain nutrition of provitamin A carotenoids. In vitro digestion model was used in this study to assess the effect of drying temperatures of heat pump and dietary fat on the bioaccessibility of β-carotene in carrots. Also, low-speed centrifugation was employed to obtain β-carotene release rate in supernatant. Microfiltration was applied to obtain β-carotene micellar rate in micelle phase. These assays were used as indicators to assess the bioaccessibility of the β-carotene. Despite higher drying temperatures had a negative effect on the retention rate of β-carotene in carrots, it showed a positive impact on the micellar rate. In addition, dietary fat significantly increased the release rate and micellar rate of β-carotene for both fresh carrots and dried carrot products, with the highest release rate and micellar rate obtained when 10% dietary fat was added. Therefore, the heat pump drying process and dietary fat can significantly improve the bioaccessibility of β-carotene in carrots, which may increase the β-carotene bioavailability to human. Keywords: bioaccessibility, in vitro digestion, β-carotene, carrot, heat pump drying DOI: 10.25165/j.ijabe.20171004.2375 Citation: Sun X F, Zhu W X, Li X L, Fan J L. Effects of heat pump drying temperature and dietary fat on carrots’ β-carotene bioaccessibility. Int J Agric & Biol Eng, 2017; 10(4): 234–242.

Peony seed meal (PSM), a protein-rich by-product of oil extraction from Paeonia ostii, represents an underutilized resource with significant potential for functional ingredient development. In this study, an integrated strategy combining artificial neural network (ANN)-guided hydrolysis, peptidomics, molecular simulation, and cellular validation was employed to identify antioxidant peptides from PSM. Neutrase was selected as the optimal protease, and hydrolysis conditions were optimized using a backpropagation ANN model (R = 0.9935), yielding a hydrolysate with strong radical-scavenging activity (DPPH^• IC₅₀ = 0.30 mg/mL; ABTS^•+ IC₅₀ = 0.07 mg/mL). LC–MS/MS identified 364 peptides, predominantly low-molecular-weight sequences. In silico screening highlighted four candidates (FRF, WQFR, FEFR, and RWL) with favorable binding toward ABTS^•+, DPPH^•, and Keap1. Molecular docking and 100 ns molecular dynamics simulations confirmed stable peptide–Keap1 interactions, particularly for FRF. Cellular assays demonstrated that FRF and RWL significantly protected HepG2 cells against H₂O₂-induced oxidative damage by restoring antioxidant enzyme activities (SOD, CAT, and GSH-Px). Collectively, this study establishes a systematic workflow for discovering plant-derived antioxidant peptides and supports the sustainable valorization of PSM as a functional food ingredient.

Peony seed meal (PSM) is an abundant byproduct after oil extraction with high protein content. To enhance the antioxidant and aroma properties of PSM hydrolysate (PSMH), Maillard reaction-mediated glycation was performed using ribose, xylose, fructose, or glucose. Among all treatments, ribose-derived Maillard reaction products (MRPs-ribose) exhibited the most pronounced Maillard reaction progression and the strongest antioxidant activity, increasing DPPH and ABTS radical-scavenging rates by 45.50% and 46.30% versus PSMH. FTIR analysis indicated higher β-sheet and lower random-coil contents, reflecting a more ordered conformation. MRPs-ribose also showed a more negative ζ-potential and reduced polydispersity index, suggesting improved dispersion stability. HS-SPME–GC–MS analysis identified 22 volatile compounds, demonstrating enrichment of aldehydes and pyrazines and a more complex aroma profile. Cellular assays confirmed MRPs-ribose restored HepG2 viability to 91.9% after H₂O₂ injury, outperforming PSMH. Collectively, these results support ribose-mediated Maillard glycation as an effective strategy to upgrade PSMH for functional food and nutraceutical applications.