Structural Characterization, Physicochemical Stability, and Antioxidant Activity of Rice Glutelin Hydrolysates

Rice Bran Proteins Extracted by Different Methods: Structural Properties and Antioxidant and Anti-Photoaging Activities of Their Hydrolysates

Differences in the composition, microstructure, infrared spectral characteristics, and enzymatic hydrolysis properties of rice bran protein extracted by four methods were investigated, and the antioxidant and anti-photoaging activities of peptides derived from the resulting hydrolysates were further evaluated. Rice bran protein obtained via ultrasonic pretreatment combined with alkaline solublilization and acid precipitation (URP) exhibited relatively high purity (59.17%) and extraction yield (47.61%), together with increased surface porosity, enhanced hydration capacity, and improved enzymatic hydrolysis performance. The URP hydrolysate (URPP) showed a protein content of 81.00%, a degree of hydrolysis of 33.57%, and marked antioxidant activity (ABTS, 684.21; ORAC, 2016.15 μmol TE/g sample). The identified peptides were predominantly short and enriched in hydrophobic amino acids. Structural analysis suggested that the indole N-H group of tryptophan may play an important role in the antioxidant activity of these peptides. Moreover, these peptides alleviated UVB-induced photoaging in HaCaT cells by reducing oxidative stress and inflammatory responses and downregulating the mRNA expressions of AP-1, MMP-1 and MMP-3. Overall, these findings reveal an association between the extraction method, structural characteristics, and enzymatic hydrolysis properties of rice bran protein and the biological activities of its derived peptides, providing a basis for the high-value utilization of rice bran protein and the development of antioxidant and anti-photoaging functional ingredients.

Alcalase hydrolysis enhances solubility and foaming properties of perilla protein isolate through structural modification

Laccase-induced structural remodeling of cottonseed protein for improving its emulsion stability and curcumin bioaccessibility.

BACKGROUND Cottonseed is an important byproduct of cottonseed processing and is rich in proteins. A literature review indicated that cottonseed protein isolate (CPI) demonstrated a compact structure because of its limited exposure of hydrophobic groups, leading to poor emulsifying performance. This limited the functional performance and practical application of CPI in food systems. This study aimed to enhance CPI interfacial functionality through laccase-induced structural remodeling and to evaluate its performance in curcumin (Cur)-loaded emulsions. RESULTS This study designed a control group (0%) and laccase-treated groups (0.3%, 0.5%, and 0.8%, w/w). It was found that protein aggregation and network formation became more pronounced following laccase treatment and followed a dose-dependent pattern. Importantly, this investigation revealed that free sulfhydryl and free amino groups decreased, whereas random coil content, hydrophobic residue exposure, surface hydrophobicity, emulsifying activity, foaming capacity and oil-holding capacity increased, in which surface hydrophobicity increased by 61.09%, and emulsifying activity, foaming capacity, and oil-holding capacity increased by 30.55%, 57.24%, and 10.94%, respectively. Pearson correlation analysis showed that surface hydrophobicity was closely related to functional improvement. Compared with the control, 0.8% laccase-modified CPI produced smaller, more uniform Cur-loaded droplets. Encapsulation efficiency increased from 74.04% to 81.97%, and Cur bioaccessibility increased from 26.84% to 40.88%. CONCLUSION These findings indicated that laccase modification improved the functional properties and interfacial characteristics of CPI by altering its molecular conformation, thereby enhancing the encapsulation and bioaccessibility of Cur. This study provided a promising strategy for improving the delivery of hydrophobic bioactive compounds through enzymatic modified proteins. © 2026 Society of Chemical Industry.

Impact of rutin-protein nanoparticles on extruded recombinant rice: structure, digestibility and in vitro fermentation.

BACKGROUND Rutin, a flavonol polyphenol, inhibits α-glucosidase activity and reduces starch digestibility, yet its application is limited by poor aqueous solubility, poor thermal stability, and low bioaccessibility. Rutin-protein nanoparticles have been shown to improve rutin stability. This study aimed to investigate how rutin-protein nanoparticles modulate the digestibility of extruded recombinant rice through multi-scale structural characterization, in vitro digestibility analysis, and in vitro fermentation evaluation. RESULTS Multi-scale structural analysis revealed that rutin was successfully incorporated into the recombinant rice matrix, interacting with starch chains through hydrogen bonding. This interaction promoted the transformation of starch crystallinity from A-type to A- + V-type. Additionally, the short-range order and the content of single and double helices increased. In vitro digestion experiments demonstrated that the bioaccessibility of rutin in the recombinant rice reached 92.49% after co-extrusion with rutin nanoparticles. The resistant starch content was significantly increased, while C∞ (final digestion extent) and eGI (estimated glycemic index) value were significantly reduced. Moreover, in vitro fermentation results indicated that the recombinant rice with rutin nanoparticles contributed to reducing gas production and increasing the yields of propionate and butyrate. CONCLUSION Rutin nanoparticles modulate starch digestibility through a dual mechanism involving the modification of starch structural domains and rutin bioaccessibility. This study provides a novel strategy and technical support for the development of low-glycemic-index functional staple foods. © 2026 Society of Chemical Industry.

Comparative Structural Characterisation and In Vitro Bioactivities of Crude and Purified Polysaccharides from Dandelion (Taraxacum officinale) Root Using Microwave-Assisted Enzymatic Extraction

The increasing demand for functional products has promoted research on bioactive compounds. Dandelion root polysaccharide (DRP), a key bioactive component of Taraxacum officinale, has anti-inflammatory, antioxidant, hypoglycemic and hypolipidemic activities. This study extracted DRP via microwave-assisted enzymatic extraction (MAEE) to obtain mDRP, and isolated acidic polysaccharide mDRP-1 (7.548 kDa) by column chromatography. HPLC showed that both contain six monosaccharides (Man, Rha, GalA, Glu, Gal, Ara) with different molar ratios. mDRP is heterogeneous (trace protein/nucleic acids, no triple helix, amorphous), while mDRP-1 has a triple-helical, semi-crystalline structure; both have characteristic polysaccharide peaks and pyranose rings, and rough, porous surfaces. mDRP had better thermal stability and significant concentration-dependent in vitro antioxidant and hypoglycaemic effects.

Physicochemical Characterization of Freeze-Dried Low-Molecular-Weight Lychee Polyphenol/Cyclodextrin Systems with Enhanced Antioxidant Activity

Low-molecular-weight lychee polyphenol (Lyp), a standardized oligomeric polyphenol derived from Litchi chinensis fruit, possesses potent antioxidant activity but is susceptible to physicochemical instability, which may limit its practical application. In this study, freeze-dried systems of Lyp with α-, β-, and γ-cyclodextrins (CDs) were prepared to investigate the effects of cyclodextrins on the physicochemical properties and antioxidant activity of Lyp. Powder X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, near-infrared spectroscopy, and solution-state NMR were employed to characterize the prepared systems. Freeze-drying produced amorphous Lyp/CD systems accompanied by enhanced thermal stability and changes in the hydrogen-bonding environment compared with the corresponding physical mixtures. Solution-state 1H NMR and NOESY analyses suggested molecular association between Lyp constituents and cyclodextrins, with the βCD system exhibiting the most pronounced spectral changes. Consistent with these physicochemical findings, the freeze-dried βCD system showed the greatest enhancement of DPPH radical scavenging activity among the three cyclodextrins examined. These results suggest that βCD provides the most favorable molecular environment for Lyp, leading to improved physicochemical characteristics and antioxidant performance. The present findings demonstrate that freeze-drying combined with β-cyclodextrin is an effective strategy for improving the physicochemical performance and antioxidant functionality of low-molecular-weight lychee polyphenol.