Antioxidant and Neuroprotector Influence of Endo-Polyphenol Extract from Magnesium Acetate Multi-Stage Addition in the Oak Bracket Medicinal Mushroom, Phellinus baumii (Agaricomycetes).

The objective of this study was to explore the effect of magnesium acetate (MA) addition on the endo-polyphenol yield by Phellinus baumii and establish a feasible additive strategy. The optimal three-point MA addition strategy (0.05 g/L concentration of MA added at 0 h and 6 h, 0.9 g/L concentration of MA added at 12 h) was employed to obtain maximum endo-polyphenol yield. The maximum endo-polyphenol production was reached at 1.22 g/L, which was 1.39-fold higher than that of the control. Additionally, the endo-polyphenol showed stronger antioxidant activity in vitro compared with the control, including DPPH· scavenging capacity (78.76%) and Trolox equivalent antioxidant capacity (TEAC) (32.28 µmol Trolox/g sample). HPLC analysis showed that the endo-polyphenol production of the crude ethanol extracts was significantly higher than that of the control. Hispidin was isolated and identified from the ethanol extract of the culture mycelia from Ph. baumii with the three-point MA addition strategy. Hispidin showed a strong ability to scavenge DPPH free radicals and TEAC, equivalent to positive (vitamin C) value of 89.41% and 75.98%, respectively. Furthermore, hispidin protected H2O2-induced PC12 cells injured by decreased oxidative stress level. These results indicated that the MA multi-stage addition strategy was dependable, and could be used to develop new natural antioxidants for foods or medicines.

A new continuous system of enzymatic hydrolysis coupled with membrane separation for isolation of peptides with angiotensin I converting enzyme inhibitory capacity from defatted corn germ protein.

In this study, separation of peptides with Angiotensin I converting enzyme (ACE)-inhibitory capacity obtained from ultrasonically pretreated defatted corn germ protein (DCGP) by using a new continuous system of enzymatic hydrolysis coupled with membrane separation (EHC-MS) was investigated. Ultrasonic pretreatment was applied to enhance the enzymatic hydrolysis rate of DCGP, as proved in our previous study. The EHC-MS system was operated in two modes which included the batch system and continuous system with continuous water and substrate feeding and was compared with the EH-offline-MS system. The selection of the membrane was based on the hydrolysate fraction which had the highest activity for inhibition of ACE. The results showed that the 1-3 kDa fraction of DCGP hydrolysates had the lowest IC50 value (0.124 mg mL-1) for inhibition of ACE. The degree of conversion (%) of DCGP and output of peptides per unit of the enzyme were significantly (P < 0.05) increased by 55.3% and 55% in the EHC-MS batch process and 79% and 473% in the EHC-MS continuous operation compared to the EH-offline-MS system. The EHC-MS using continuous water and substrate feeding operation was noted to be the best in terms of a high degree of DCG protein conversion (75.68 ± 1.34) and the output of peptides per unit of the enzyme (78.65 ± 1.13). The results revealed that the EHC-MS method with constant water and substrate feeding could show a better application in peptide production in the food industry.

Effect of a multi-frequency counter-current S-type ultrasound pretreatment on the defatted corn germ protein: enzymatic hydrolysis, ACE inhibitory activity and structural characterization.

In this work, a defatted corn germ protein (DCGP) was pretreated with single frequency ultrasound at 20 kHz (SFU) and multi-frequency ultrasounds (20, 28, 35 and 40 kHz) (MFU). The microstructures, morphology, amino acid content, degree of hydrolysis, protein hydrolysate concentration and angiotensin-converting enzyme (ACE) inhibitory activity of the DCGP hydrolysate were analyzed. The results showed that both SFU and MFU pretreatments increased the ACE inhibitory activity of the DCGP hydrolysate more than that observed for the traditional method. Also, the SFU pretreatment showed the highest ACE inhibitory activity of 54% in comparison with that of the DCGP hydrolysates obtained via the traditional and MFU pretreatment methods. The results of ultraviolet-visible (UV-Vis) spectroscopy, fluorescence spectroscopy, surface hydrophobicity studies, Fourier-transform infrared spectroscopy (FTIR), atomic force microscopy (AFM) and scanning electron microscopy (SEM) confirmed the extent of the changes that occurred in the microstructures and morphology of DCGP pretreated with SFU and MFU. The results also indicated that the hydrophobic amino acid concentration was comparably higher in DCGP pretreated with SFU and MFU than that in the DCG protein isolated via the traditional method.

Influence of doum (Hyphaene thebaica L.) flour addition on dough mixing properties, bread quality and antioxidant potential.

In this covenant of functional foods, the world seeks for new healthier food products with appropriate proportions of bioactive constituents such as fiber, mineral elements, phenols and flavonoids. The doum fruit has good nutritional and pharmaceutical properties; therefore, its incorporation in breads could be beneficial in improving human health. In the current study, partial substitution of wheat flour (WF) with doum fruit flour (DFF) at levels of 5 %, 10 %, 15 % and 20 % were carried out to investigate the dough viscoelastic properties, baking performance, proximate compositions and antioxidant properties of the breads. Partial substitution of WF with DFF increased the water absorption and developing time of dough (P ≤ 0.05), while, the dough extensibility, resistance to extension and the deformation energy were reduced. Bread supplemented with DFF resulted in a reduction in quality in terms of specific loaf volume, conferred softness, hardness, cohesiveness and gumminess to the bread crumbs. DFF up to 15 % could partially replace WF in bread; increase its nutritional value in terms of fiber content and minerals, with only a small depreciation in the bread quality. Sensory evaluation showed that breads supplemented up to 15 % DFF were acceptable to the panelists and there was no significant difference in terms of taste, texture and overall acceptability compared to the control. The incorporation of DFF increased the total phenolic contents, total flavonoids contents and antioxidant properties compared to the control (for both flour and bread).

Electrochemical Genosensor To Detect Pathogenic Bacteria (Escherichia coli O157:H7) As Applied in Real Food Samples (Fresh Beef) To Improve Food Safety and Quality Control.

The electrochemical genosensor is one of the most promising methods for the rapid and reliable detection of pathogenic bacteria. In a previous work, we performed an efficient electrochemical genosensor detection of Staphylococcus aureus by using lead sulfide nanoparticles (PbSNPs). As a continuation of this study, in the present work, the electrochemical genosensor was used to detect Escherichia coli O157:H7. The primer and probes were designed using NCBI database and Sigma-Aldrich primer and probe software. The capture and signalizing probes were modified by thiol (SH) and amine (NH2), respectively. Then, the signalizing probe was connected using cadmium sulfide nanoparticles (CdSNPs), which showed well-defined peaks after electrochemical detection. The genosensor was prepared by immobilization of complementary DNA on the gold electrode surface, which hybridizes with a specific fragment gene from pathogenic to make a sandwich structure. The conductivity and sensitivity of the sensor were increased by using multiwalled carbon nanotubes (MWCNT) that had been modified using chitosan deposited as a thin layer on the glass carbon electrode (GCE) surface, followed by a deposit of bismuth. The peak currents of E. coli O157:H7 correlated in a linear fashion with the concentration of tDNA. The detection limit was 1.97 × 10(-14) M, and the correlation coefficient was 0.989. A poorly defined current response was observed as the negative control and baseline. Our results showed high sensitivity and selectivity of the electrochemical DNA biosensor to the pathogenic bacteria E. coli O157:H7. The biosensor was also used to evaluate the detection of pathogen in real beef samples contaminated artificially. Compared with other electrochemical DNA biosensors, we conclude that this genosensor provides for very efficient detection of pathogenic bacteria. Therefore, this method may have potential application in food safety and related fields.

Biotransformation of stevioside by Leuconostoc citreum SK24.002 alternansucrase acceptor reaction.

Stevioside (13-O-ß-sophorosyl-19-O-ß-d-glucosyl-steviol) is a non-cariogenic and low-calorigenic diterpenoid glycoside. It has a slightly bitter taste and bad aftertaste. Enzymatic modification by alternansucrase from Leuconostoc citreum SK24.002 was utilised in the biotransformation of stevioside to fully or partially remove the bitter taste of the stevioside. The effect of the reaction conditions including, time (1-24h), temperature (20-40°C), pH (4-7), donor concentration (10-100mg/ml) and enzyme concentration (0.5-2.5U/ml) were investigated in order to maximise the transglucosylation yield. The highest transglucosylation yield of approximately 43.7% was achieved at 20°C, pH 5.4 for 24h using sucrose at 10mg/ml and alternansucrase at 1U/ml. LC/MS analysis confirmed that the product was composed of mono-di- and tri- glucosylated stevioside and their isomers.