An active film from silver carp skin gelatin incorporated with green tea extract (GTE) was developed. The effects of GTE concentrations including 0.3 and 0.7% (w/v) on the film properties were ...determined by measuring total polyphenolic content, antioxidant activity and physical properties. The findings of this study showed that the incorporation of GTE into gelatin films enhanced the total phenolic content, DPPH radical scavenging activity and reducing power. However, DPPH radical scavenging activity and reducing power decreased during storage. As regards the physical properties, higher GTE content incorporated into gelatin films revealed significantly higher tensile strength and lower elongation at break, water solubility and water vapor permeability, but no difference in thickness. Gelatin–GTE films exhibited lower light transmission in UV light, lower percent transmittance and higher transparency value compared to control film. Moreover, protein patterns of gelatin–GTE films had no changes. The thermal stability of gelatin–GTE films was improved and grew with the increasing concentration of GTE. FTIR spectra indicated that protein–polyphenol interactions were involved in the gelatin–GTE films. Smooth and homogeneous surface and compact-structure were observed in gelatin–GTE films. Thus, the addition of GTE into gelatin film improved the antioxidant activity and directly affected the properties most likely due to the interactions between gelatin and GTE.
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► Gelatin films incorporated with GTE possessed antioxidant activity. ► The incorporation of GTE into gelatin film improved tensile strength, light barrier and water vapor barrier. ► Protein–polyphenol interactions were involved in the improvement of the properties of gelatin–GTE film.
Foodborne illnesses caused by the consumption of berries contaminated with human enteric viruses, namely human noroviruses (NoVs) and the hepatitis A virus (HAV), remain a significant food safety ...concern. The objective of this research was to investigate a food-grade edible coating composed of alginate/oleic and containing green tea extract (GTE) as an antiviral agent for the preservation of fresh strawberries and raspberries. Berries were stored at ambient (25 °C) temperature and refrigerated (10 °C) conditions. Initially, the effect of the pH of the film-forming dispersions (FFD) on their antioxidant and antiviral activity was analysed. Then, the physicochemical properties of edible alginate-oleic acid coatings containing GTE were studied, and finally, their antiviral efficacy when applied onto strawberries and raspberries at 10 and 25 °C was evaluated. The results showed that the antioxidant properties of the films were not pH-dependent, but the antiviral activity was higher at a pH 5.5. The infectivity of the murine norovirus (MNV), a human norovirus surrogate, and HAV in fresh strawberries after the coating treatments was reduced by approximately 1.5–2 log during the 4-days storage period at 10 °C as compared to the controls and a complete inactivation of both viruses was observed after overnight storage at 25 °C. However, the efficacy of the GTE-coatings was slightly reduced on the raspberries, probably due to the difference in the amount of coating that adhered to their surface (4.64 ± 0.23 g and 1.54 ± 0.15 g⋅cm−2 for strawberries or raspberries, respectively). Therefore, this paper reports, for the first time, the potential of antiviral edible coatings to improve the safety of berries against foodborne pathogens.
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•Antiviral food-grade coatings containing green tea extract (GTE) were prepared.•The antioxidant properties of the films were not pH-dependent.•The antiviral activity against MNV and HAV was higher at pH 5.5.•Antiviral coatings were effective at ambient and refrigerated conditions.•The antiviral efficacy of GTE-coatings was greater in strawberries than in raspberries.
As part of the United States Pharmacopeia’s ongoing review of dietary supplement safety data, a new comprehensive systematic review on green tea extracts (GTE) has been completed. GTEs may contain ...hepatotoxic solvent residues, pesticide residues, pyrrolizidine alkaloids and elemental impurities, but no evidence of their involvement in GTE-induced liver injury was found during this review. GTE catechin profiles vary significantly with manufacturing processes. Animal and human data indicate that repeated oral administration of bolus doses of GTE during fasting significantly increases bioavailability of catechins, specifically EGCG, possibly involving saturation of first-pass elimination mechanisms. Toxicological studies show a hepatocellular pattern of liver injury. Published adverse event case reports associate hepatotoxicity with EGCG intake amounts from 140 mg to ∼1000 mg/day and substantial inter-individual variability in susceptibility, possibly due to genetic factors. Based on these findings, USP included a cautionary labeling requirement in its Powdered Decaffeinated Green Tea Extract monograph that reads as follows: “Do not take on an empty stomach. Take with food. Do not use if you have a liver problem and discontinue use and consult a healthcare practitioner if you develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice (yellowing of the skin or eyes).”
•GO was biogenically reduced to RGO by a green tea extract.•Pb(II) removal efficiency was related to GO reduction conditions.•Highest Pb(II) removal (97.2%) by RGO occurred.•This study provides new ...insights into the mechanism of GO reduction.
Graphene has a great potential in environmental remediation due to its unique physical and chemical properties. However, the relationships between synthetic conditions and contaminant removal are still unclear. In this study, a biogenic method was used for the reduction of graphene oxide (GO) using green tea extract and the reduced graphene oxide (RGO) produced was subsequently used to remove Pb(II) from aqueous solution. Hence, the impact of bioreduction synthetic conditions of RGO on Pb(II) removal efficiency was examined. The new findings included (1) that reduction of GO by green tea (GT) extract at a ratio of 2:1 (GO:GT), 80 °C and pH 8, led to a RGO material capable of removing 97.2% of a 10 mg·L−1 Pb(II) solution under the adsorption conditions of pH 4.5 and a RGO dose of 0.4 g·L−1 at 30 °C; (2) characterization results showed good dispersion of RGO, and removal of oxygen functional groups from GO, increased Pb(II) adsorption. Pb(II) removal efficiency was largely dependent on reduction conditions during synthesis of RGO; where efficient removal of oxygen-containing groups during reduction favored Pb(II) removal. Furthermore, during biogenic synthesis RGO was also capped by biomolecules such as polyphenols which decreased aggregation leading to enhanced Pb(II) removal efficiency.
This study investigates the interaction of fish oil-protein and phenolic-rich green tea extract on the physico-chemical quality, lipid oxidation and bacteriostatic properties of different treatments ...of surimi gel incorporated with fish oil (FO) and Pseuderanthemum palatiferum freeze-dried powder (PFP). The incorporation of 3–6% FO, and 100–200 mg PFP/100 g surimi were investigated. The effect of PFP on the FO-fortified surimi gel had a positive effect on the textural and bio-potential properties. FO-PFP samples showed a higher water-holding capacity than the control gel. Fourier transform infrared spectroscopy (FT-IR) analysis of the surimi gel confirmed the successful blending of oil-protein and phenolic compounds present in PFP. The antioxidant activity and oxidative stability of PUFA-enriched oil increased with the addition of FO-PFP; moreover, the addition of PFP showed good antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Listeria monocytogenes. Hence, the combination of small amounts of PFP in oil-emulsified surimi gel could help in obtaining good-quality surimi gel fortified with health-beneficial polyunsaturated fatty acids that have antibacterial properties.
•Surimi from Alaska Pollock was added with SC-CO2 extracted fish oil and green tea extract (PFP).•FT-IR results showed the successful blending of gel protein-fish oil-phenolic components from PFP.•PFP incorporation showed inhibitory effect on lipid oxidation of surimi gel.•PFP increased the antioxidant and bacteriostatic activity against common foodborne bacteria.
•Active HPMC films based containing antioxidant PLA nanoparticles were developed.•Green tea extract was encapsulated in PLA nanoparticles by emulsion nanoprecipitation.•Films containing the loaded ...nanoparticles released the antioxidant into food simulants.•Developed films can be used to package food products with high fat contents.
A novel active film material based on hydroxypropyl-methylcellulose (HPMC) containing poly(lactic acid) (PLA) nanoparticles (NPs) loaded with antioxidant (AO) green tea extract (GTE) was successfully developed. The PLA NPs were fabricated using an emulsification-solvent evaporation technique and the sizes were varied to enable a controlled release of the AO from the HPMC matrix. A statistical experimental design was used to optimise the synthesis of the NPs in order to obtain different sizes of nanoparticles and the loading of these into the HPMC matrix was also varied. The physico-chemical properties of the composite films were investigated and the release of the AO was confirmed by migration studies in 50% v/v ethanol/water food simulant. The AO capacity of the GTE released from the active films was studied using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical method and the results suggest that the material could potentially be used for extending the shelf-life of food products with high fat content.
The aim of the study was to determine the impact of three factors: dough preparation method (direct and indirect), green tea extract (GTE) addition (0.1% and 0.5% on flour basis) and baking ...temperature (230 and 260 °C) on rye bread quality and acrylamide (AA) content. All factors and their interaction had significant influence on quality parameters of dough and bread. pH of dough prepared by direct method was higher. Addition of GTE increased dough TTA, porosity and bread volume and decreased hardness of bread crumb. Breads prepared by indirect method had darker color of crust, which may be due to the higher amount of Maillard reaction products. Acrylamide formation in breads prepared from dough acidified by lactic acid (direct method) was 3.5 times lower than in breads from dough fermented by starter cultures (indirect method). Effect of GTE seemed to be unclear, because in breads made by direct method AA formation was not significantly different, however, in fermented sourdoughs content of this harmful component increased. All of the samples baked in lower temperature (230 °C) contained in average 25% less AA than baked in 260 °C.
•Rye breads made by direct method had 3.5 times lower AA content than made by indirect method.•In this study GTE did not show the possibility to use it as AA mitigation strategy.•GTE at levels of 0.1 and 0.5% in sourdough rye bread increased AA level.•Breads baked in lower temperature were characterized by 25% lower AA content.•All experimental factors influenced significantly quality parameters of rye bread.
In this work, a green tea extract (GTE) was encapsulated within electrosprayed protein (i.e. gelatin and zein) microparticles, and the protective ability of both systems on the green tea catechins ...was assessed. The microparticles (with encapsulation efficiencies ∼90 g/100 g), proved to be very effective in stabilizing the catechins during a thermal treatment at 180 °C (12 min), preserving 85–90 g/100 g of their initial catechins content, while free GTE lost almost 40 g/100 g of its catechins content. In order to assess the impact of microencapsulation in a real food system, the GTE-loaded electrosprayed microparticles were added to biscuits dough. Results showed that microencapsulation did not significantly protect during biscuit processing and emphasized the need of assessing the behaviour of microencapsulation systems in real food processing conditions. The sensorial analysis of the biscuits indicated that addition of the GTE-loaded microparticles did not impact the acceptability of the biscuits, as perceived by consumers.
•Catechin-containing protein microcapsules were developed through electrospraying.•A great thermal protection ability of the microcapsules was observed.•Microencapsulation did not improve antioxidant capacity in biscuit doughs.•Addition of loaded microcapsules did not affect sensorial properties of biscuits.
For the optimization of silver nanoparticle production, a central composite design was used with three parameters: AgNO3 concentration, green tea extract concentration, and temperature at three ...different levels. The size of the synthesized silver nanoparticle, its UV absorbance, zeta potential, and polydispersity index were set as the response parameters. Silver nanoparticles obtained in the optimization process were characterized and its efficacy on colorimetric detection of mercury was evaluated. The response variables were significant for the factors analyzed, and each variable had a significant model (P < 0.05). The ideal conditions were: 1 mM AgNO3, 0.5% green tea extract, and 80 °C temperature. To analyze the produced AgNPs under certain ideal conditions, Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used. The UV–visible spectra of AgNPs revealed an absorption maxima at 424 nm. The XRD pattern reveals a significant diffraction peak at 38.25°, 44.26°, 64.43°, and 77.49°, which corresponds to the (111), (200), (220), and (311) planes of polycrystalline face-centered cubic (fcc) silver, respectively. The TEM and SEM analyses confirmed that the particles were spherical, and dynamic light scattering study determined the average diameter of AgNPs to be 77.4 nm. The AgNPs have a zeta potential of −62.6 mV, as determined by the zeta sizer analysis. The AgNPs detects mercury at a micromolar concentration. Furthermore, the environmentally friendly generated AgNPs were used to detect mercury in a colorimetric method that was effectively employed for analytical detection of Hg2+ ions in an aqueous environment for the purpose of practical application.
•Green tea extracts mediated AgNPs were synthesized by wet chemical reduction.•Central Composite Design was used to synthesize AgNPs with a high level of precision.•For detecting Hg2+, AgNPs showed great selectivity and sensitivity.•AgNPs are utilized to detect Hg2+ in real-world samples of water.
A nanoparticlulate delivery system was prepared for developing a food grade carrier for the major bioactive constituent in green tea; (─)-epigallocatechingallate (EGCG), in order to protect it ...against degradation during storage and digestion under simulated gastrointestinal pH conditions. EGCG-loaded solid lipid nanoparticles (EGCG-SLNs) were produced by the hot homogenization method. The lipid matrix used in the production consisted of pure cocoa butter. A combination of sodium stearoyl-2-lactylate (SSL) and mono- and diglycerides (MDG) was applied as a surfactant blend. The nanoparticles loaded with different concentrations of EGCG had an average particle size in the range of 108–122 nm. A maximal encapsulation efficiency of 68.5% was obtained. The produced food grade SLNs successfully protected the encapsulated EGCG along the storage period as well as under the adverse conditions at neutral pH values. The developed system offers good potential for enriching food products with EGCG.
•Solid lipid nanoparticles (SLNs) were made from cocoa butter and food-grade surfactant blend.•The system was developed for introducing Epigallocatechin-3-gallate (EGCG) into food products.•EGCG-loaded SLNs system significantly enhanced the stability of EGCG at pH 6.8.•The encapsulation of EGCG did not affect the particle size characteristics of SLNs.•A prolonged release of EGCG from SLNs during in-vitro tests was reached.
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