Green and efficient in-situ biosynthesis of antioxidant and antibacterial bacterial cellulose using wine pomace.

Biologically active bacterial cellulose (BC) was efficiently synthesized in situ using wine pomace and its hydrolysate. The structural and biomechanical properties together with the biological functions of the BC were investigated. Functional BC from wine pomace and its enzymatic hydrolysate were of high purity and had higher crystallinity indexes (90.61% and 89.88%, respectively) than that from HS medium (82.26%). FTIR results proved the in-situ bindings of polyphenols to the functionalized BC. Compared to BC from HS medium, wine pomace-based BC had more densely packed ultrafine fibrils, higher diameter range distributions of fiber ribbon, but lower thermal decomposition temperatures, as revealed by the SEM micrographs and DSC data. Meanwhile, wine pomace-based BC exhibited higher loads in tensile strength and higher hardness (4.95 ± 0.31 N and 5.13 ± 0.63 N, respectively) than BC in HS medium (3.43 ± 0.14 N). Furthermore, BC synthesized from wine pomace hydrolysate exhibited a slower release rate of phenolic compounds, and possessed more antioxidant activities and better bacteriostatic effects than BC from wine pomace. These results demonstrate that BC synthesized in situ from wine pomace (especially from enzymatic hydrolysate) is a promising biomolecule with a potential application in wound dressing, tissue engineering, and other biomedical fields.

Bio-conversion of kitchen waste into bacterial cellulose using a new multiple carbon utilizing Komagataeibacter rhaeticus: Fermentation profiles and genome-wide analysis.

A cellulose-producing bacterium Komagataeibacter rhaeticus K15 was isolated from kombucha tea, and its metabolic pathways and cellulose synthesis operon were analyzed by genome sequencing. Different from the reported K. rhaeticus, the K15 produced little gluconic acid (2.26 g/L) when glucose was the sole carbon source and has the capacity for high cellulose production (4.76 g/L) with other carbon sources. Furthermore, six nitrogen-fixing genes were found to be responsible for the survival of K15 on a nitrogen-free medium. Based on its fermentation characteristics, K15 was cultured in a kitchen waste medium as a strategy for green and sustainable bacterial cellulose production. The SEM, XRD, and FTIR results indicated that synthesized cellulose has a mean diameter of 40-50 nm nanofiber, good crystallinity, and the same chemical structure. The K15 strain provides a highly viable alternative strategy to reduce the costs of bacterial cellulose production using agro-industrial residues as nutrient sources.

Soy protein isolate -(-)-epigallocatechin gallate conjugate: Covalent binding sites identification and IgE binding ability evaluation.

The conjugate prepared from (-)-epigallocatechin gallate (EGCG) and soy protein isolate (SPI) under alkaline and aerobic conditions was analyzed using a Nano-LC-Q-Orbitrap-MS/MS technique. The sulfhydryl and free amino groups of SPI were involved in covalent binding. Fifty-one peptides were conjugated with EGCG. Fifty-nine modified sites were identified, located on Cys, His, Arg, and Lys, respectively. It is the first time to confirm that each of the two phenolic rings of EGCG contained a reactive site that bound to an amino acid residue. The amino acid residue reactivity, amino acid sequence and composition affected the EGCG binding site in SPI. Lys and Arg residues are the most likely sites for modification, and modification appears to reduce IgE binding. This study is helpful to elucidate the pattern of covalent binding of polyphenols to proteins in food systems and provides a theoretical basis for the directional modification of soy proteins with polyphenols.

High hydrostatic pressure enhances the anti-proliferative properties of lotus bee pollen on the human prostate cancer PC-3 cells via increased metabolites.

ETHNOPHARMACOLOGICAL RELEVANCE: The beneficial effects of bee pollen on prostate diseases are well known. Clinicians confirm that, in nonbacterial prostate diseases, bee pollen improves the condition of patients effectively. However, there is insufficient evidence to rate effectiveness of bee pollen on prostate cancer. AIM OF THE STUDY: High hydrostatic pressure (HHP), an effective non-thermal technique to improve the nutritional quality and bio-functionality of plant-based foods, was used to increase the anti-proliferative properties of Lotus (Nelumbo nucifera) bee pollen (LBP) in prostate cancer PC-3 cells via enhancement of bioactive compounds. MATERIALS AND METHODS: Freeze-dried lotus bee pollen produced from Fu Zhou city, Jiangxi province, China, was processed by high hydrostatic pressure (HHP). The anti-proliferative activities, apoptosis of ethanol and methanol extracts in prostate cancer PC-3 cells was evaluated using MTT method and Annexin-V/PI cell apoptosis assay kit, respectively. The changes of metabolites were determined using UPLC-Triple-TOF-MS analysis platform. RESULTS: HHP treatment enhanced anti-proliferative activities, cell apoptosis, cell cycle disruption, glutathione-depletion in prostate cancer PC-3 cells. The metabolomics analysis showed that some metabolites such as chaetoglobosin A, glutathione oxidized, cyanidin 3-rutinoside, brassicoside, sophoranone, curcumin II, soyasaponin II were significantly increased (p < 0.05) after the HHP treatment, PCA results shown that these bioactive components have quite correlation with anti-proliferative activities of lotus bee pollen on the PC-3 cells. The results indicated that HHP enhances the anti-prostate cancer activity of lotus bee pollen via increased metabolites.

Effect of non-covalent and covalent complexation of (-)-epigallocatechin gallate with soybean protein isolate on protein structure and in vitro digestion characteristics.

The present study was aimed to investigate the effects of non-covalent and covalent interactions between soy protein isolate (SPI) and different concentrations (1, 2 and 5 mM) of (-)-epigallocatechin gallate (EGCG) regarding the structural and functional properties of the complex. The combination with EGCG caused changes in the secondary structure of SPI. The covalent complexes formed at low concentrations of EGCG tended to form a network structure. Compared with the SPI-EGCG non-covalent complexes, the covalent complexes exhibited higher thermal stability and oxidation resistance and a polyphenol-protective effect. In addition, the corresponding anti-digestive ability of the covalent complexes was strong and would therefore be more stable in the intestinal tract. The findings of this study provide a theoretical reference and research basis for the use of different SPI-polyphenol complexes as functional food ingredients or as bioactive materials.

On-line screening and identification of free radical scavenging compounds in Angelica dahurica fermented with Eurotium cristatum using an HPLC-PDA-Triple-TOF-MS/MS-ABTS system.

Eurotium cristatum, a beneficial fungus isolated from Fuzhuan tea, was used to ferment Angelica dahurica for the first time. The antioxidant capacities of the extracts before and after fermentation were compared using ABTS, DPPH and FRAP assays. The results showed that the antioxidant capacities of the extracts acquired using organic solvents were greater after fermentation. Moreover, based on a comparison of the HPLC chromatograms, the chemical composition of Angelica dahurica changed substantially during fermentation. To further understand the changes in its antioxidant constituents, an on-line HPLC-PDA-Triple-TOF-MS/MS-ABTS system was employed. Twelve antioxidants belonging to three different classes were detected and identified, and their antioxidant capacities were preliminarily evaluated. The results indicated that the substances produced during the fermentation of Eurotium cristatum played important roles in enhancing the antioxidant capacity.

Combined Effect of Polyphenol-Chitosan Coating and Irradiation on the Microbial and Sensory Quality of Carp Fillets.

Irradiation can extend the shelf-life of fish, but it may cause unacceptable change on quality. Since rose polyphenols have high antioxidant and antibacterial activities, this study evaluated the combined effect of polyphenol-chitosan coatings and irradiation (3 kGy) on the microbial and sensory qualities of carp fillets during storage at 4 °C. A dose of 3 kGy irradiation reduced the initial total viable counts (TVC) and psychrophiles, and increased the initial b* and thiobarbituric acid reactive substance (TBARS) values. During storage, TBARS, TVC and psychrophiles of nonirradiated samples increased faster and were higher than those irradiated. Regardless of irradiation treatment, samples coated with chitosan containing rose polyphenols had lower TBARS, pH and bacteria than that in no coating or chitosan coating batches. Carp treated with combined treatment could preserve an acceptable sensory quality at the end of storage. The result indicated that polyphenol-chitosan coating combined with irradiation can maintain fish quality by preventing bacterial growth, oxidation, and changes in color and sensory acceptability.