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BACKGROUND: Chitosan (CS) and tripolyphosphate (TPP) can be combined in the development of a material with synergistic properties and promising potential for the conservation of food products. In this study, ellagic acid (EA) and anti‐inflammatory peptide (FPL)‐loaded CS nanoparticles (FPL/EA NPs) were prepared using the ionic gelation method and optimal preparation conditions were obtained through a single factor design. RESULTS: The synthesized nanoparticles (NPs) were characterized using a scanning electron microscope (SEM), Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and differential scanning calorimetry (DSC). Nanoparticles were spherical, with an average size of 308.33 ± 4.61 nm, a polydispersity index (PDI) of 0.254, a zeta potential of +31.7 ± 0.08 mV, and a high encapsulation capacity (22.16 ± 0.79%). An in vitro release study showed that EA/FPL had a sustainable release from FPL/EA NPs. The stability of the FPL/EA NPs was evaluated for 90 days at 0, 25, and 37 °C. Significant anti‐inflammatory activity of FPL/EA NPs was verified by nitric oxide (NO) and tumor necrosis factor‐α (TNF‐α) reduction. CONCLUSION: These characteristics support the use of CS nanoparticles to encapsulate EA and FPL and improve their bioactivity in food products. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The walnut meal is a by-product of walnut oil pressing, which contains a large amount of protein and active compounds. The Walnut protein was hydrolyzed with different proteases, its hydrolysis efficiency and acetylcholinesterase (AChE) inhibitory activity were evaluated, and alkaline protease and pepsin hydrolysis were selected to prepare the walnut protein hydrolyses. The ultrafiltered protein hydrolysate (molecular weight < 3 kDa) was divided into 3 fractions using Sephadex G-25 gel chromatography and its inhibitory activity against AChE was tested. Peptides of the F3 component peptides showed the best inhibitory activity of AChE with half-inhibitory concentrations of 330.58 ± 0.37 μg/mL. Therefore, liquid chromatography mass spectrometry (LC–MS/MS) was used to identify bioactive peptides in the F3 component. Molecular docking was used to screen for potential inhibitory AChE peptides, and the results demonstrated that the interaction between the peptides and AChE could be performed by hydrogen bonds, π-alkyl bonds, and alkyl bonds. Tyr-Val-Pro-His-Trp (YVPHW), Phe-Tyr-Arg-Arg (FYRR), and Leu-Ala-Pro-Phe (LAPF) peptides identified from walnut meal exhibited a strong inhibitory effect of AChE with the half-inhibitory concentration of 184.61 ± 0.62 μg/mL, 359.64 ± 0.53 μg/mL, and 320.52 ± 0.38 μg/mL. YVPHW had a synergistic effect with linoleic acid. This revealed that the addition of YVPHW and linoleic acid to foods might be an excellent choice for food scientists designing diets for Alzheimer’s patients. [ABSTRACT FROM AUTHOR]

This study is aimed at the preparation and evaluation of walnut meal-derived elastase inhibitory peptide loaded in chitosan-tripolyphosphate (CS-TPP) nanoparticles (NPs). It was shown that the maximum encapsulation efficiency of FFVPF could reach 94.58 ± 0.23%. TEM microphotographs, polydispersity index, and zeta-sizer reports indicated that FFVPF-loaded CS-TPP NPs were in nanometric range and were spherical, discrete, and uniform in size with PDI less than 0.3. FTIR analysis indicated that the peptides interacted with CS-TPP NPs through strong hydrogen bonds and electrostatic interactions. The CS-TPP FFVPF NPs showed better stability with heating treatment, pH treatment, or photochemical treatment. Moreover, the in vitro release profile of peptides was identified. The release rate of encapsulated FFVPF was released explosively to 77.22 ± 2.21% and gradually slowed down. These findings highlighted the prospect of CS-TPP NPs as an oral delivery system, and the application of peptides within food and pharmaceutical products. [ABSTRACT FROM AUTHOR]

The present study evaluated the effect of fermentation with Lactiplantibacillus plantarum B7 and Bacillus subtilis natto on phenolic compound levels and enzyme activity, as well as antioxidant capacity of the rose residue. Results showed that the polyphenol content of rose residue was significantly increased from 16.37 ± 1.51 mg/100 mL to 41.02 ± 1.68 mg/100 mL by fermentation at 37 °C and 2.0% (v/v) inoculum size for 40 h. The flavone, soluble dietary, and protein contents were also enhanced by almost 1-fold, 3-fold, and 1-fold, respectively. Fifteen phenolic compounds were quantified in the fermented broth, among which the concentration of gallic acid, quercetin, and p -coumaric acid increased by 5-fold, 4-fold, and almost 8-fold, respectively. Chlorogenic acid was a new phenolic compound produced during fermentation. Moreover, the fermented rose residue presented higher superoxide dismutase, α-amylase, and protease activity. ABTS•+, hydroxylradical, and DPPH• scavenging activity increased by 60.93%, 57.70%, and 37.00%, respectively. This provides an effective means of transforming rose residue into a highly bioactive value-added substance. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • FGGDSTHP, ALGGGY, YVVPW, and PLLRW were identified. • The synergistic MIC was 1.0 mg/mL of YVVPW and 0.27 mg/mL of SA. • Hydrogen bonds in YVVPW + SA were related to Tyr and Val residue. • π-π stacking was correlated with the five-membered ring of Trp residue. This study aimed to identify an antimicrobial peptide and phenolic compound combination derived from fermented walnut meal against Penicillium. victoriae , a fungus responsible for Rosa. roxbughii Tratt spoilage, and ultimately investigate their synergistic mechanism. YVVPW and salicylic acid (SA) had the highest antifungal activity among identified 4 antimicrobial peptides, including FGGDSTHP, ALGGGY, YVVPW, and PLLRW, and 15 phenolic compounds, respectively. Molecular docking verified that YVVPW bound to regulatory subunit via hydrogen-bond, hydrophobic, and π-π conjugate interactions. YVVPW and SA exhibited synergistic effects with average minimal inhibitory concentration decreasing by 85.44 ± 8.04%. Fluorescence spectroscopy demonstrated quenching of intrinsic Trp and Tyr fluorescence by interaction. FTIR and molecular docking results revealed formation of 3 hydrogen bonds via OH, C O, N H, and C H bonds in YVVPW + SA, with π-π stacking occurring between the benzene ring and five-membered ring. These reinforce potential application of this combination as an effective fungistatic combination in fruit preservation. [ABSTRACT FROM AUTHOR]

Rosa roxburghii Tratt residue is rich in dietary fiber and a variety of active substances, but its dietary fiber is mainly insoluble dietary fiber, and the content of soluble dietary fiber (SDF) is low. To make full use of R. roxburghii Tratt residue, steam explosion (SE) pretreatment was used to treat the residue to determine its effect on the extraction yield of SDF and the functionality of dietary fiber (DF). Response surface methodology was used to determine the conditions of SE for optimizing the SDF extraction yield in the residue. When R. roxburghii Tratt residue was pretreated by SE at 60 mesh for 97 s, combined with 0.87 MPa, the content of SDF was increased from 9.31 ± 0.07% to 15.82 ± 0.31% in comparison with the control and DF extracted by SE showed the high cholesterol adsorption, glucose adsorption, cation exchange, nitrite adsorption, and hydroxyl radicals inhibition. Practical applications: Due to the rough texture and poor taste, the high content of DF in the Rosa roxburghii Tratt residue is often discarded during the processing of freshly squeezed juice. SE can significantly improve the utilization of DF, which is a more economical modification method. This work provides a theoretical basis for the R. roxburghii Tratt by‐product as a new source of high‐quality dietary fiber. [ABSTRACT FROM AUTHOR]

Selenium nanoparticles (SeNPs) have attracted lots of attention recently owing to their excellent bioavailability and low toxicity. However, the stability of SeNPs needs to be improved. To enhance the stability of SeNPs, we used Spirulina platensis polysaccharides (SPs) as stabilizers to prepare SPs‐SeNPs. The SPs‐SeNPs were spherical, with a mean particle size of 73.42 ± 0.69 nm. The optimal preparation conditions for the SPs‐SeNPs were a SPs concentration of 100 mg/L, ascorbic acid/sodium selenite concentration ratio of 3:1 and reaction time of 6 hr. The prepared SPs‐SeNPs were stable for 75 d at 4°C. Furthermore, MTT assay showed that the median toxic concentration (TC50) of SPs‐SeNPs was approximately 22,000 μg/L. In contrast, the TC50 value of selenite was approximately 400 μg/L, which confirmed that the cytotoxicity of SPs‐SeNPs on RAW264.7 cells was significantly reduced compared with sodium selenite. In conclusion, SPs can improve the stability of SeNPs. The toxicity of SPs‐SeNPs is lower than that of sodium selenite. Practical applications: Spirulina platensis polysaccharides can improve the stability and reduce the toxicity of selenium nanoparticles. It can lay the foundation for the comprehensive utilization of S. platensis and the development and research of polysaccharide nano‐selenium complexes. [ABSTRACT FROM AUTHOR]

Spirulina platensis is a high-nutrient blue-green alga with a long history as a food supplement. In this study, the mixed fermentation of Spirulina with Lactobacillus plantarum and Bacillus subtilis was investigated using random-centroid optimization to improve deodorization of off-flavor and hydrolysis of protein. Fermented Spirulina with the maximum total viable counts of both organisms achieved best sensory characteristics and degree of proteolysis among those with different maximum biomass. The mixed fermentation noticeably reduced the volatile compounds of Spirulina , and yielded the highest relative contents (>85%) of acetoin and other odorants collectively producing a creamy aroma. Approximately one-third of the Spirulina proteins were hydrolyzed, yielding over 16% polypeptides and increasing the ratio of essential amino acids to total free amino acids to 1.5-fold compared with unfermented Spirulina . Fermentation with B. subtilis and L. plantarum effectively improved the odor and protein availability of Spirulina . [ABSTRACT FROM AUTHOR]

This study evaluated transepithelial transport mechanisms of Ile‐Gln‐Pro (IQP) and Val‐Glu‐Pro (VEP), two ACE‐inhibitory peptides derived from Spirulina platensis, using human intestinal Caco‐2 cell monolayers. IQP and VEP were absorbed intact through Caco‐2 cell monolayers with Papp values of 7.48 ± 0.58 × 10−6 and 5.05 ± 0.74 × 10−6 cm/s, respectively. The transport of IQP and VEP were affected neither by Gly‐Pro nor by wortmannin, indicating that they were not PepT1‐mediated and did not involve endocytosis. However, transport of IQP and VEP were increased significantly by sodium deoxycholate, suggesting that the major transport mechanism was paracellular. In addition, the increased transport of VEP and IQP were followed with the addition of sodium azide, suggesting influence of energy to the process. The transport of VEP was also increased by verapamil, indicating an apical‐to‐basolateral flux mediated by P‐gp. Practical Application: Bioactive peptides derived from food proteins have been considered as potentially ideal products to reduce hypertension because of their safety and positive impacts on health. IQP and VEP are the 2 ACE inhibitory peptides derived from Spirulina platensis, a kind of edible cyanobacteria with rich nutrition and multiple physiological functions, and were demonstrated to inhibit ACE and lower blood pressure in spontaneously hypertensive rats. However, it is prerequisite that such bioactive peptides must be absorbed intact across the intestinal epithelium, so as to exert antihypertensive effects in vivo. This study evaluated transepithelial transport mechanisms of IQP and VEP. It contributes to the study of Spirulina in lowering blood pressure and supports the development of bioactive peptide products. [ABSTRACT FROM AUTHOR]

The aim of the present study was to evaluate the protective effect and mechanism of Letinous edodes foot peptides on ethanol‑induced L02 cells. A cell model of ethanol‑induced damage was established in vitro to study the effects of the Letinous edodes foot peptides on human L02 hepatocytes. The expression and activity of superoxide dismutase (SOD), malondialdehyde (MDA), aspartate aminotransferase (AST), alanine aminotransferase (ALT), alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH), following treatment were examined to determine the anti‑alcoholism and hepatoprotective functions of Letinous edodes foot peptides. Taking Letinous edodes foot peptides prior to ethanol exposure was more beneficial, which significantly increased SOD activity and the mRNA expression of ADH and ALDH suppressed by ethanol. In addition, the intracellular MDA content, and AST and ALT activity decreased in ethanol‑induced L02 cells pretreated with the peptides, when compared with the control. Furthermore, Letinous edodes foot peptides inhibited the ethanol‑induced activation of the proinflammatory cytokines, interleukin‑6 and tumor necrosis factor‑α, and promoted the metabolic regulation factors, AMP‑activated protein kinase‑α2 and peroxisome proliferator‑activated receptor‑α. [ABSTRACT FROM AUTHOR]

Diospyros lotus , a member of the Ebenaceae family, has long been used as a traditional sedative in China. In this study, the antioxidant and hypoglycemic effects of non-fermented and microorganism-fermented D . lotus were explored. The total phenolic and vitamin C contents of microorganism-fermented D . lotus for 24–72 h were less than those of non-fermented. High-performance liquid chromatography showed that the tannic, catechinic, and ellagic acid contents increased significantly upon fermentation for 24 h. D . lotus fermented with Microbacterium flavum for 24 h exhibited the highest DPPH radical scavenging activity (IC 50 = 4.18 μg mL −1 ), and the highest ABTS radical scavenging activity was exhibited at 72 h of fermentation (IC 50 = 29.18 μg mL −1 ). The anti-α-glucosidase activity of fermented D . lotus was higher (2.06–4.73-fold) than that of non-fermented one. Thus, fermented D . lotus is a useful source of natural antioxidants, and a valuable food, exhibiting antioxidant and hypoglycemic properties. [ABSTRACT FROM AUTHOR]

Elsholtzia ciliate is mainly used in folk medicine for the treatment of cold, fever, dysentery and digestion disorder. The aim of our study is to investigate the composition of supercritical fluid extract of Elsholtzia ciliate and to study its antimicrobial and antioxidant activity. In our research, the extract of Elsholtzia ciliate was extracted using the CO2 supercritical fluid extraction (SFE) and then its chemical constituents were analyzed by gas chromatography-mass spectrometry (GC-MS). Seventeen components were identified by GC-MS analysis which mainly include elsholtzia ketone (9.16 %), 9,12,15-octadecatrienoic acidethyl ester (13.74 %), 9,12-octadecadienoic acid (13.59 %), tetratriacontane (11.25 %), and octacosane (9.49 %). A good antibacterial effect of the extract has been proved by an experiment performed in an antibacterial assay with minimum inhibitory concentration (MIC) values and inhibition zone. Moreover, the extract showed low levels of antioxidant capacity in the DPPH assay, as well as slight inhibitory activity in a β-carotene bleaching assay. The results of this research show that the extracts of Elsholtzia ciliata might be a natural potential source of food preservatives and antioxidants. [ABSTRACT FROM AUTHOR]

This study was to find an effective process to extract bioactive peptides from mushroom foot and determine their effects on activation of alcohol metabolic enzymes in vitro. The optimum extraction assisted by ultra-high-pressure processing of mushroom foot peptides was obtained with a pressure of 400 MPa and a processing time of 10 min. After ultrafiltration, peptides with molecular weight of 0–3 kDa had the highest activity to activate alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) by 70.79% and 71.35%, respectively. Following dextran gel chromatography, two peaks (p-I and p-II) appeared and the activation activities on ADH and ALDH of p-I were 72.00% and 73.43%, both higher than p-II. Nine peptides were found in p-I as determined by LC–MS/MS, and two of them (IPLH and IPIVLL) were synthesized. IPLH activated ADH and ALDH by 42.7% and 29.2% respectively, which were higher than IPIVLL. [ABSTRACT FROM AUTHOR]

BACKGROUND Spirulina platensis is rich in β-carotene, which possesses many important biological activities. This study investigated the ultrasound-assisted extraction and purification of β-carotene from Spirulina platensis by using response surface methodology ( RSM), determined its antioxidant capacity in vitro and explored its hypoglycaemic effect in diabetic mice. RESULTS The raw β-carotene extract with a concentration of 1942.14 ± 10.03 µg mL−1 was obtained at the optimised condition by RSM (0.40 of the solid-liquid ratio, 51% of the extraction power, and 17 min of the extraction time), and the purity of evaporated β-carotene extract reached 816.32 ± 10.57 mg g−1 after purified by a NKA-9 resin with a sampling and elution rate of 1 mL min−1. The β-carotene extract scavenged 1,1-diphenyl-2-picrylhydrazyl and hydroxyl free radicals with the highest ratios of 44 ± 0.26% and 35 ± 0.45% respectively, and exhibited strong inhibiting capacity on anti-lipid peroxidation. The blood glucose level of streptozotocin-induced diabetic mice was significantly reduced from 15.81 ± 1.71 mmol L−1 to 8.10 ± 0.88 mmol L−1 after 10 d administration of the β-carotene extract [100 mg kg−1 body weight ( BW)], and the increased food and water intakes in the diabetic mice were also significantly relieved after β-carotene treatment. CONCLUSION Our results suggested that extraction of β-carotene from Spirulina platensis had potential prospects in scaled-up industrialisation and healthcare applications. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Atlantic salmon ( Salmo salar L.) bones (normally discarded during manufacturing) were used to prepare salmon ossein oligopeptides (SOOP). Calcium-chelating salmon ossein oligopeptides (SOOP-Ca) were obtained by calcium-chelating peptides from SOOP. The calcium-chelating capacity of SOOP-Ca was 52.47 ± 0.08 %. SOOP-Ca had high protein content (63.42 ± 1.02 %) and low molecular weight, and 72.32 % of the molecular weight was less than 1 ku. Scanning electron microscopy, ultraviolet wavelength scanning and infrared spectra all showed that the structure of SOOP-Ca is different from that of SOOP. SOOP-Ca was stable at a range of temperatures and at various pH values. It was also stable during in vitro gastric protease digestion. SOOP-Ca was separated by reversed-phase high-performance liquid chromatography. Ten major fractions were collected and subjected to mass spectrometry to identify peptide components. A total of 22 peptide sequences were identified. This study suggested that SOOP-Ca might be useful as food additives, dietary nutrients and pharmaceutical agents which could promote calcium absorption. [ABSTRACT FROM AUTHOR]

• PEN/PET bottles are made by blending polyethylene terephthalate and polyethylene naphthalate. • PEN/PET bottles possessed significant gas barrier properties. • PEN/PET bottles could prevent losses of VC, SOD, and TPC during beverage storage. • PEN/PET bottles extend the shelf life of chestnut rose beverages by 70 days at 4 °C. The shelf life of chestnut rose beverage is largely dependent on packaging method and storage temperature. In this study, we investigated the effects of packaging beverages in bottles made of either polyethylene terephthalate (PET) or PEN (polyethylene naphthalate)/PET and storage temperature (4, 25, 37, and 55 ℃) on the shelf life of chestnut rose beverage. The physicochemical parameters and enzyme activity of beverages were evaluated, and we found that at 4 °C, the vitamin C, superoxide dismutase, and total polyphenol contents of beverages stored in PEN/PET bottles increased by 9.95 ± 0.49%, 2.86 ± 0.13%, and 3.23 ± 0.09% respectively, compared to beverages in ordinary PET bottles. In addition, other characteristic indicators including total soluble solids, browning index, and color value were also significantly improved. A shelf-life model was established based on the Arrhenius equation, and it will help distributors and consumers to determine the storage time and optimal shelf life of chestnut rose beverage. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to determine the effect of microwave-assisted hydrothermal extraction (MHE) on the bioactive compounds, phenolic profile, and antioxidant activities of dateplum persimmon (Diospyros lotus L) juice and vinegar, compared to those prepared by microwave (ME) and hydrothermal (HE) extraction. Results showed that following optimization by response surface methodology, the total phenolic content of dateplum persimmon juice reached 166.8 ± 2.2 mg/g at 131 °C, 26 mL/g, 390 W, and 32 min. The microstructural morphological changes to dateplum persimmon juice and their bioactive compound contents were ranked in the order of MHE-, HE-, and ME-prepared, and untreated juice from highest to lowest. Both MHE-prepared juice and vinegar presented high polyphenol, protein, and polysaccharide contents. Pyrogallol, gallic acid, protocatechuic acid, quercetin-3β-D-glucoside, ellagic acid, quercetin, maslinic acid, and ursolic acid were identified in juice and vinegar. Compared to untreated dateplum persimmon juice and vinegar, the IC 50 values for the DPPH•, ABTS•+, and •OH scavenging activities were decreased by 71.4% and 70.8%, 72.4% and 70.7%, and 50.2% and 48.3% for juice and vinegar prepared by MHE, respectively. These findings suggest that MHE can be used as a novel technology for preparing phenolic-rich and high-antioxidant activity juice and vinegar. • MHE was optimized for preparing phenolic-rich dateplum persimmon juice. • MHE enhanced polyphenol, protein, and polysaccharide contents of dateplum persimmon juice and vinegar. • Protocatechuic acid was the most increased polyphenol by MHE. • MHE improved the antioxidant activities of juice and vinegar by 2-fold. [ABSTRACT FROM AUTHOR]

• A novel tyrosinase inhibitory peptide FPY was identified from defatted walnut meal. • The interaction forces between FPY and the receptor were clarified. • The inhibition type of FPY on tyrosinase was competitive and reversible. • The peptide FPY can resist the degradation of digestive enzymes in vitro. Defatted walnut meal protein was hydrolyzed using alcalase to yield tyrosinase inhibitory peptides. After separation by ultrafiltration and Sephadex G-25, the fraction with the highest tyrosinase inhibitory activity was identified using liquid chromatography-tandem mass spectrometry and 606 peptides were obtained. Then, molecular docking was used to screen for tyrosinase inhibitory peptides and to clarify the theoretical interaction mechanism between the peptides and tyrosinase. A peptide with the sequence Phe-Pro-Tyr (FPY, MW: 425.2 Da) was identified and the synthesized peptide inhibited tyrosine monophenolase and diphenolase with IC 50 values of 1.11 ± 0.05 and 3.22 ± 0.09 mM, respectively. The inhibition of tyrosinase by FPY was competitive and reversible. Good stability of FPY toward digestion was observed in an in vitro gastrointestinal digestion simulation experiment. These results indicated that FPY can be used as a potential tyrosinase inhibitor in the food, medicine, and cosmetics industries. [ABSTRACT FROM AUTHOR]

• Edible films are made by blending degradable whey protein isolate, chitosan with antibacterial properties and microcrystalline cellulose. • Edible films possessed significant mechanical properties. • Multilayer PET bottles made from edible films possessed significant barrier properties. • Multilayer PET bottles could prevent losses of polyphenols during storage. • Multilayer PET bottles extend the shelf life of rosebud beverages by 38 days at 4 °C. Multilayer bottles consisting of chitosan (CS), microcrystalline cellulose (MCC), whey protein isolate (WPI), and polyethylene terephthalate (PET) were tested as novel materials for packaging and extending shelf life of rosebud beverages. We studied the storage stability at 4 °C, 25 °C, 37 °C, and 55 °C by assessing the physical and biochemical parameters. The results show that multilayer PET bottles had better barrier performance and improved soluble solids content, pH, polyphenol content, color indices, and browning degree in rosebud beverages over the control at all studied temperatures. A shelf life model was established based on the Arrhenius equation, and the number of days when polyphenol contents dropped to <50% of the initial content was defined as the shelf life. Our results highlight the reliability of the prediction model, and we conclude that packaging rosebud beverages in multilayer PET bottles significantly extends the product shelf life, and this benefit was further extended at low temperatures. [ABSTRACT FROM AUTHOR]

• A method of phycocyanin glycation promoted by ultra-high pressure was explored. • Phycocyanin can fully conjugate with dextran 20,000 in composite modification. • Some functions of CM-PC (composite modified phycocyanin) were enhanced. • Functional properties of CM-PC improved after hydroxyl groups being introduced. Phycocyanin (PC), a plant-based protein with interesting biological activity, is rarely directly applied in the food industry because it has structural and functional limitations. This study combined ultra-high-pressure (UHP) treatment with glycation to improve PC functionality and explored resulting structural changes using sodium dodecyl sulfate-polyacrylamide gel electrophoresis, scanning electron microscopy, Fourier-transform infrared spectroscopy, circular dichroism, and UV–visible spectroscopy. The UHP treatment obviously improved the speed and degree of glycation and the composite-modified PC (CM-PC) showed high solubility and good emulsifying and foaming performance. Scanning electron microscopy images showed the CM-PC surface was loose and fluffy. Gel electrophoresis, Fourier-transform infrared spectroscopy, and circular dichroism results demonstrated that the content of α-helix decreased from 78.1% in PC to 26.6% in CM-PC, and hydroxyl groups were introduced. UV–visible spectroscopy showed that the mechanism of composite modification involved stretching of the PC and promotion of binding with sugars. [ABSTRACT FROM AUTHOR]