Hanju Sun

Physicochemical properties and antioxidant activities of polysaccharide from floral mushroom cultivated in Huangshan Mountain.

In this paper, a polysaccharide fraction (FMPS) was purified from the floral mushroom cultivated in Huangshan Mountain for the first time. Physicochemical properties and antioxidant activities of FMPS were investigated. FMPS had an average molecular weight of 7.2×10(5)Da and was composed of glucose. On the basis of FT-IR, NMR and methylation analysis, the repeating unit of FMPS was established as (1→3)-linked β-d-glucopyranosyl backbone with 1-linked β-d-glucopyranosyl branches substituted at O-6 position of (1→3)-linked β-d-glucopyranosyl residues. The advanced structure studies indicated that FMPS was a triple-helical polysaccharide. The main hydrodynamic radius (Rh) of FMPS was 23.4nm and it could form a stable system with water in 1.2×10(-2)g/mL solutions. In addition, FMPS exhibited high DPPH radical scavenging activities (79.46% at 5mg/mL) and hydroxyl radical scavenging activities (74.18% at 5mg/mL), as well as Fe(2+)chelating activities and ABTS radical scavenging activities to some extent.

Optimization of Enzymatic Hydrolysis Conditions for Preparation of Gingko Peptides from Ginkgo Nuts

Ginkgo nuts were used as raw material and peptides were prepared in turn with Neutral protease and Flavourzyme. In single-factor experiments of Neutral protease, conditions of temperature, pH, enzyme concentration and substrate concentration were optimized in term of degree of hydrolysis (DH). Based on the results of single-factor experiments, an orthogonal experiment (L9(3)4) was conducted to optimize the hydrolysis conditions of Neutral protease. The results showed that enzyme concentration, substrate concentration, reaction temperature and initial pH were the main variables that influenced DH. The highest DH was obtained when hydrolysis time, reaction temperature, initial pH, enzyme amount and substrate concentration were 4 h, 45 oC, 7.0, 1.8 mg/mL and 0.02 g/mL, respectively. Subsequently, the resulting solution was further hydrolyzed with Flavourzyme. Initial pH, temperature, time and enzyme concentration were optimized in term of DH. Finally, another orthogonal experiment (L9(3)4) was conducted to get the best enzymatic conditions of Flavourzyme, and enzyme concentration, initial pH, temperature and time were used as factors. The results showed that when Flavourzyme concentration, reaction temperature, initial pH and hydrolysis time were 9.0 mg/mL, 50 oC, 7.0 and 5 h, respectively, DH was the highest. The final degree of hydrolysis was 22.56%.

Isolation and prebiotic activity of water-soluble polysaccharides fractions from the bamboo shoots (Phyllostachys praecox)

The water-soluble polysaccharides from bamboo shoots (Phyllostachys praecox) (WBP) were isolated, and the characterizations as well as prebiotic activities were investigated. The yield of WBP was 7.58±0.31% under optimal hot-water extraction conditions. Two fractions, i.e., WBP-1 and WBP-2 with molecular weight of 83.50kDa and 80.08kDa, respectively, were purified by chromatography. Both the polysaccharides fractions were identified as heteropolysaccharides-protein complexes composed of 15 kinds of common amino acids in protein part and rhamnose, arabinose, xylose, mannose, glucose and galactose in different molar ratios in polysaccharide part. The existence of α- and β-glycosidic linkages between the sugar units was confirmed by FTIR and NMR spectra. Compared with the blank control and the reference of FOS, WBP-1 and WBP-2 significantly increased the numbers of Bifidobacterium adolescentis and Bifidobacterium bifidum (P<0.05), which contributed to the production of organic acids, suggesting that the polysaccharides have potential prebiotic properties.

Purification and characterization of polyphenol oxidase from rape flower.

The purification and partial enzymology characteristics of polyphenol oxidase (PPO) from rape flower were studied. After preliminary treatments, the crude enzyme solution was in turn purified with ammonium sulfate, dialysis, and Sephadex G-75 gel chromatography. The optimal conditions and stability of PPO were examined at different pH values and temperatures. Subsequently, PPO was also characterized by substrate (catechol) concentrations, inhibitors, kinetic parameters, and molecular weight. Results showed that the optimal pH for PPO activity was 5.5 in the presence of catechol and that PPO was relatively stable at pH 3.5-5.5. PPO was moderately stable at temperatures from 60 to 70 °C, whereas it was easily denatured at 80-90 °C. Ethylenediaminetetraacetic acid, sodium chloride, and calcium chloride had little inhibitive effects on PPO, whereas citric acid, sodium sulfite, and ascorbic acid had strongly inhibitive effects. The Michaelis-Menten constant (K(m)) and maximal reaction velocity (V(max)) of PPO were 0.767 mol/L and 0.519 Ab/min/mL of the crude PPO solution, respectively. PPO was finally purified to homogeneity with a purification factor of 4.41-fold and a recovery of 12.41%. Its molecular weight was 60.4 kDa, indicating that the PPO is a dimer. The data obtained in this research may help to prevent the enzymatic browning of rape flower during its storage and processing.

Rapeseed polysaccharides as prebiotics on growth and acidifying activity of probiotics in vitro.

In vitro digestibility, prebiotic activity and chemical composition of polysaccharides from rapeseed were deliberately studied in this paper. After preliminary treatments, two fractions of polysaccharides (RP1 and RP2) were obtained after purification by DEAE-cellulose and Sephadex G-100. Their primary structural feature and molecule weights were characterized. Furthermore, their digestibility was also evaluated by artificial gastric juice and α-amylase. Finally, their proliferative effect on bifidobacteria and lactobacilli and acid production of the resulting probiotics in vitro were investigated. The results showed that RP1 and RP2 were homogeneously protein-bound polysaccharides with molecular weights of 28.51 and 6.55 kDa, respectively. They were resistant to hydrolysis by artificial gastric juice and α-amylase. Moreover, they could also significantly stimulate the tested probiotics to proliferate and produce organic acids. These findings clearly suggest the polysaccharides from rapeseed are potential to be exploited as novel prebiotics.

Antioxidant activity and sensory characteristics of Maillard reaction products derived from different peptide fractions of soybean meal hydrolysate

Four peptide fractions PF1 (>5;kDa), PF2 (3-5;kDa), PF3 (1-3;kDa), PF4 (<1;kDa) were isolated from soybean hydrolysate using the ultrafiltration method. Then, d-xylose and l-cysteine were reacted with specific peptide solution at 120;°C for 2;h, and the molecular weight distribution (MWD), pH, colour, browning intensity, DPPH radical-scavenging activity, free amino acids and sensory characteristics of corresponding Maillard reaction products (MRPF1, MRPF2, MRPF3 and MRPF4) were evaluated, respectively. Peptides with low molecular weight showed higher contribution to the changes of pH, colour and browning intensity during Maillard reaction. The DPPH radical-scavenging activity of PF4 was significantly improved after Maillard reaction. Aroma volatiles and PLSR analysis suggested MRPF3 had the best sensory characteristics with higher contents of umami amino acids and lower of bitter amino acids, therefore it could be deduced that the umami and meaty characteristics were correlated with the peptides of 1-3;kDa.

Extraction and preliminary characterization of polysaccharide from Umbilicaria esculenta cultivated in Huangshan Mountain

In this study, the effects of extraction temperature, extraction time and liquid–solid ratio on the extraction yield of polysaccharide (HSSEP) from Umbilicaria esculenta cultivated in Huangshan Mountain were investigated using Box–Behnken response surface design. A second-order polynomial equation was employed to optimize the heat water extraction of HSSEP. The optimal extraction conditions of HSSEP were: 100.37 °C extraction temperature, 0.98 h extraction time and 11.02 mL/g liquid–solid ratio. Under these conditions, the maximum extraction yield of HSSEP was 27.68%. Additionally, two purified polysaccharide fractions, designated as HSSEP1 and HSSEP2, were prepared from HSSEP. The results indicated that HSSEP1 and HSSEP2 were acidic polysaccharides. HSSEP1 was mainly composed of mannose, glucose and galactose, in a ratio of 12%, 76% and 12%, respectively, while HSSEP2 was mainly composed of glucose. This study demonstrated the optimal extraction conditions and structure characterizations of HSSEP for the first time.

PEGylation of black kidney bean (Phaseolus vulgaris L.) protein isolate with potential functironal properties

In this work, we investigated PEGylated black kidney bean protein isolates (BKBPI) by PEG succinimidyl carbonate (PEG-SC), PEG succinimidyl succinate (PEG-SS) and PEG succinimidyl propionate (PEG-SPA) conjugation. The functional properties, thermodynamic stability, in vitro digestion stability, and hemagglutination activity of the modified products were evaluated. The degree of PEGylation was measured, and FTIR analysis revealed that protein-PEG conjugations were formed, and that no obvious changes in water- and fat-holding capacities were observed. The solubility, emulsifying property, and foaming property were all improved through the modification, while, higher thermodynamic stability was achieved with the increase in Td values and reduction of ΔH. The PEGylated proteins were found to be more resistant to in vitro digestion, and the hemagglutination activity was significantly (P < 0.05) decreased, indicating the higher safety of the protein isolate. The results showed that the functional properties, thermodynamic stability, and biological safety of BKBPI were improved by PEGylation, which could serve to increase the applications for this protein.

Antioxidant and prebiotic activity of five peonidin-based anthocyanins extracted from purple sweet potato (Ipomoea batatas (L.) Lam.)

Twelve kinds of anthocyanins from the Chinese purple sweet potato cultivar (Ipomoea batatas (L.) Lam.) were extracted and identified using LC-MS/MS, which had a high content of peonidin-based anthocyanins. Five peonidin-based anthocyanin monomers (P1, P2, P3, P4 and P5) were isolated by preparative liquid chromatography with structural analyses using an Impact II Q-TOF MS/MS. Then, the functional properties of the anthocyanin monomers, such as the antioxidant activities, proliferative effects on probiotics, and their inhibition on harmful bacteria in vitro, were investigated. The peonidin-based components in purple sweet potato anthocyanins (PSPAs) showed good properties regarding scavenging 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and superoxide anions, and had good potential in reducing the total power activity and Fe2+ chelating ability. While the order of the antioxidant abilities was as follows: P4 > P5 > P3 > P2 > P1 > PSPAs. Microbial cultivations showed that P1, P2, P3, P4, P5 and PSPAs could induce the proliferation of Bifidobacterium bifidum, Bifidobacterium adolescentis, Bifidobacterium infantis and Lactobacillus acidophilus, and they inhibited the growth of Staphylococcus aureus and Salmonella typhimurium, suggesting the anthocyanins might have prebiotic-like activity through the modulation of the intestinal microbiota. Our results indicate that peonidin-based anthocyanins could be further utilized in health foods and pharmaceutical developments.

Metabolism and prebiotics activity of anthocyanins from black rice (Oryza sativa L.) in vitro

Anthocyanins are naturally active substances. In this study, anthocyanins from black rice were obtained by membrane filtration and column chromatography separation. Five anthocyanin monomers in black rice extract were identified by HPLC-MS/MS, and the major anthocyanin monomer (cyanidin-3-glucoside, C3G) was purified by preparative HPLC (Pre-HPLC). The proliferative effects of the anthocyanins on Bifidobacteria and Lactobacillus were investigated by determining the media pH, bacterial populations and metabolic products. After anaerobic incubation at 37 °C for 48 h, not only the pH of the media containing C3G was lower than that of the extract of black rice anthocyanin (BRAE), but the numbers of both Bifidobacteria and Lactobacillus were also significantly increased. Furthermore, hydroxyphenylpropionic, hydroxyphenylacetic, and hydroxybenzoic acids and other metabolites were detected by GC-MS in vitro. Our results revealed that the anthocyanins and anthocyanin monomers from black rice had prebiotic activity and they were metabolized into several small molecules by Bifidobacteria and Lactobacillus.