Tianli Yue

Purification and identification of five novel antioxidant peptides from goat milk casein hydrolysates.

The present research described the preparation, purification, and identification of antioxidant peptides from goat milk casein (GMC). Goat milk casein was hydrolyzed by using a combination of neutral and alkaline proteases to obtain goat milk casein hydrolysates (GMCH) with high antioxidant activity. After desalting by nonpolar macroporous absorption resin, GMCH was isolated and purified by gel filtration chromatography and reversed-phase HPLC, respectively, and further identified by nanoliter electrospray ionization-tandem mass spectrometry. Antioxidant activities of GMC, GMCH, and pure peptides were evaluated and compared using free radical scavenging activity, metal ion chelating ability, and anti-lipid peroxidation ability. Compared with GMC, the free radical-scavenging ability and ferrous ion-chelating ability of GMCH increased significantly. The inhibition effect of lipid peroxidation of GMCH was much stronger than that of tert-butylhydroquinone and phytogermine and a little lower than that of ascorbic acid. The antioxidant activity of GMCH could be attributed to the high antioxidant activity of oligopeptides, especially 5 novel oligopeptides: Val-Tyr-Pro-Phe, Phe-Gly-Gly-Met-Ala-His, Phe-Pro-Tyr-Cys-Ala-Pro, Tyr-Val-Pro-Glu-Pro-Phe, and Tyr-Pro-Pro-Tyr-Glu-Thr-Tyr, which were first observed in GMCH. The antioxidant activity of these 5 novel oligopeptides and GMCH increased 3.59 to 380 times compared with GMC, combining anti-lipid peroxidation ability of GMCH, which indicated that GMCH and its purified fractions in different stages could be used as functional food ingredients, food additives, and pharmaceutical agents in the future.

Free radical scavenging and immunomodulatory activities of Ganoderma lucidum polysaccharides derivatives

Polysaccharides extracted from the fruit body of Ganoderma lucidum were sulfated and carboxymethylated as reported. Free radical scavenging and immunomodulatory effects of sulfated and carboxymethylated polysaccharides were studied. Generally, sulfated polysaccharides showed better bioactivities than that of carboxymethylated polysaccharides. The two derivatives were injected intraperitoneally with or without 5-fluorouracil over a period of 7 days in BALB/c female mice. The polysaccharide derivatives increased mouse thymus and spleen index, an indication of improved immunity in mice. At the same time, they improved superoxide dismutase and glutathione peroxidase contents in the mice body.

Alicyclobacillus contamination in the production line of kiwi products in China.

Alicyclobacillus are spoilage microbes of many juice products, but contamination of kiwi products by Alicyclobacillus is seldom reported. This study aims to investigate the whole production line of kiwi products in China to assess the potential risk of their contamination. A total of 401 samples from 18 commercial products, 1 processing plant and 16 raw material orchards were tested, and 76 samples were positive, from which 76 strains of microbes were isolated and identified as 4 species of Alicyclobacillus, including Alicyclobacillus acidoterrestris, Alicyclobacillus contaminans, Alicyclobacillus herbarius and Alicyclobacillus cycloheptanicus, and another 9 strains as 3 species of Bacillus by sequencing of their 16S rDNA. Through phylogenetic tree construction and RAPD-PCR amplification, it was found that there exist genotypic diversities to some extent among these isolates. Four test strains (each from one species of the 4 Alicyclobacillus species isolated in this study) could spoil pH adjusted kiwi fruit juice and some commercial kiwi fruit products with producing guaiacol (11–34 ppb).

Kinetics of adsorption of bovine serum albumin on magnetic carboxymethyl chitosan nanoparticles

The magnetic carboxymethyl chitosan nanoparticles (MNPs-CMC) were developed as effective magnetic affinity adsorbent for Bovine serum albumin and the adsorption reactions were investigated. The obtained experimental data were compared with the adsorption kinetics models and equilibrium isotherms. The experimental kinetic data were modeled using Pseudo-first order, Pseudo-second order, Banghams equation, Intra-particle diffusion model and Elovich equations. It was found that the adsorption reactions followed the Pseudo-second order kinetics equation. The experimental isotherm data were analyzed using Langmuir, Freundlich, Dubinin-Radushkevich and Temkin equations. By comparing the correlation coefficients determined for each linear transformation of isotherm analysis, it was found that the Langmuir equation was the best fit equilibrium model for the adsorption of BSA. Error functions have been used to determine the alternative single component parameters by nonlinear regression due to the inherent bias in using the correlation coefficient resulting from linearization. It showed that the Langmuir equation resulted in the lowest values for the error function and thus fitted the data better than the other isotherm. Various thermodynamic parameters such as enthalpy (ΔH°), entropy (ΔS°) and Gibbs free energy (ΔG°) were evaluated. MNPs-CMC nanoaprticles were shown to be a promising material for adsorption of BSA from aqueous solutions.

Immunostimulatory activities of β-d-glucan from Ganoderma Lucidum.

A water-insoluble β-(1 → 3)-D-glucan (GLPs) with few branches at C-6 and C-2 positions was extracted from the fruit body of Ganoderma Lucidum by 1M NaOH at 40 °C. By the striking inhibition of NO and TNF-α production, GLPs showed significant anti-inflammation activity against LPS induced Raw 264.7 cells. Results of RT-PCR revealed the down regulation of iNOS and TNF-α mRNA gene expression. GLPs severely inhibited the phosphorylation of IκBα and JNK1/2, while the ERK1/2 and p38 were not apparently affected by GLPs. The neutralizing antibodies against dectin-1 and TLR-4, respectively, did not affect GLPs-mediated inhibition of NO production. But neutralizing of TLR2 affected the inhibition of NO. All of these results revealed that GLPs can inhibit the inflammation of Raw 264.7 cell induced by LPS at least partially attributed to the blocking of NF-κB and JNK MAPK, and TLR2 plays a major role in GLPs anti-inflammation activity.

Development and evaluation of an immunomagnetic separation-ELISA for the detection of Alicyclobacillus spp. in apple juice.

The immunomagnetic separation (IMS) technique was used in combination with an enzyme-linked immunosorbent assay (ELISA) procedure to shorten the total analysis time and improve the sensitivity for the detection of Alicyclobacillus spp. in apple juice samples. The specificity of IMS-ELISA for twenty strains of Alicyclobacillus spp. and eighteen strains of non-Alicyclobacillus spp. was determined and there was little cross-reaction with non-Alicyclobacillus strains. Artificially contaminated apple juice with different concentrations of Alicyclobacillus acidoterrestris was detected by IMS-ELISA, and the detection limit of the assay in apple juice was 10(3)CFU/mL. Furthermore, the sample inoculated with 1CFU/mL of A. acidoterrestris could be detected as positive after incubation for 24h. The IMS-ELISA described, allows for the identification of suspect positive samples within 3h of testing versus 3-5days required by standard culture methods while significantly reducing the materials and labor required for the detection of Alicyclobacillus spp. in apple juice samples. As compared with the standard culture method performed concurrently on the same set of samples, the sensitivity, specificity and accuracy of IMS-ELISA for 102 naturally contaminated apple juice samples were 91.3%, 96.02% and 95.09%, respectively. These results demonstrated that the newly proposed IMS-ELISA procedure can be a potentially useful analytical method for the detection of Alicyclobacillus spp. in apple juice.

Immunomodulatory of selenium nano-particles decorated by sulfated Ganoderma lucidum polysaccharides

In this study, we employed a one-step method to prepare selenium nanoparticles (SeNPs) decorated by the water-soluble derivative of Ganoderma lucidum polysaccharides (SPS). The SeNPs-SPS complexes were stable, and the diameter of the SeNPs was homogeneous at around 25 nm. We investigated the anti-inflammatory activity of SeNPs-SPS against murine Raw 264.7 macrophage cells induced by LPS. SeNPs-SPS were found to significantly inhibit LPS-stimulated nitric oxide (NO) production against Raw 264.7 macrophages. RT-PCR results reveal the down-regulation of mRNA gene expressions for pro-inflammatory cytokines, including inducible NO synthase (iNOS), interleukin (IL)-1 and TNF-α in a dose-dependent manner. However, the anti-inflammation cytokine IL-10 was markedly increased. In the NF-κB signal pathway, SeNPs-SPS significantly inhibited the phosphorylation of Iκ-Bα. Similar results were observed for inhibition of the phosphorylation of JNK1/2 and p38 mitogen-activated protein kinase(MAPKs), whereas ERK1/2 MAPK was not apparently affected by SeNPs-SPS. All of these results suggest that SeNPs-SPS complexes have anti-inflammatory potential modulating pro-/anti-inflammation cytokine secretion profiles, and that the mechanism is partially due to inhibition of activations of NF-κB, JNK1/2 and p38 MAPKs.

Immunomagnetic separation combined with polymerase chain reaction for the detection of Alicyclobacillus acidoterrestris in apple juice.

A combination of immunomagnetic separation (IMS) and polymerase chain reaction (PCR) was used to detect Alicyclobacillus acidoterrestris (A. acidoterrestris) in apple juice. The optimum technological parameters of the IMS system were investigated. The results indicated that the immunocapture reactions could be finished in 60 min and the quantity of IMPs used for IMS was 2.5 mg/mL. Then the combined IMS-PCR procedure was assessed by detecting A. acidoterrestris in apple juice samples. The agarose gel electrophoresis results of 20 different strains showed that the IMS-PCR procedure presented high specificity to the A. acidoterrestris. The sensitivity of the IMS-PCR was 2×101 CFU/mL and the total detection time was 3 to 4 h. Of the 78 naturally contaminated apple juice samples examined, the sensitivity, specificity and accuracy of IMS-PCR compared with the standardized pour plate method were 90.9%, 97.0% and 96.2%, respectively. The results exhibited that the developed IMS-PCR method will be a valuable tool for detecting A. acidoterrestris and improving food quality in juice samples.

Heavy metal levels in kiwifruit orchard soils and trees and its potential health risk assessment in Shaanxi, China

Concentrations of five heavy metals (Cr, Cu, Cd, Hg, and Pb) in orchard soils and kiwifruit tissues (root, twig, leave, fruit) collected from Shaanxi province in China were measured, and the potential health risk for human through the fruit consumption was assessed. The orchard soils were in no pollution for Cr, Cu, Hg, and Pb, with their pollution index (PI) ≤1, while 10.0xa0% of the soil samples were under Cd contamination. Furthermore, kiwifruit tended to have a higher Cd and Hg accumulation (as indicated by Biological Accumulation Coefficient) from soil and have a higher Cu and Hg translocation (as reflected by Biological Transfer Coefficient) to aboveground parts. From the human health point of view, the DIM and HRI values for all the fruit samples were within the safe limits, while for Cr, Cu, Cd, Hg, and Pb, about 22.5, 12.5, 52.5, 15.0, and 47.5xa0% of the fruit samples exceeded the national maximum permissible levels, respectively. These results showed that, although there was no possible health risk to consumers due to intake of studied kiwifruit fruits under the current consumption rate, the regular survey of heavy metal pollution levels should be performed for the kiwifruit in Shaanxi province and a strict management program should be established to reduce the amount of chemical fertilizers and pesticides used in fruit production in order to prevent the potential health risk.

Adsorptive Removal of Patulin from Apple Juice Using Ca-Alginate-Activated Carbon Beads

This study aimed to investigate the adsorption of patulin from apple juice by Ca-alginate-activated carbon (Ca-alginate-AC) beads. The capacity of patulin was determined by high-performance liquid chromatography. The results showed that Ca-alginate-AC beads have significant ability to reduce patulin from contaminated apple juice. Furthermore, the adsorption process did not affect the quality of apple juice. The effects of contact time, initial patulin concentration, adsorbent dose, and temperature were assessed. The removal percentage of patulin increased with contact time, adsorbent dose, and temperature. A reduction was also noted to bind patulin at increased levels of contamination. The equilibrium data were fitted to Langmuir, Freundlich, and Temkin isotherm models and the isotherm constants were calculated at different temperatures. The adsorption equilibrium was best described by the Freundlich isotherm (R(2) > 0.990). The pseudo 1st-order model was found to describe the kinetic data satisfactorily. Thermodynamic parameters such as standard Gibbs free energy (ΔG◦◦), standard enthalpy (ΔH◦), and standard entropy (ΔS◦) were evaluated. The results showed that the adsorption was spontaneous and endothermic nature.