Tea Residue Research Articles

Development and Characterization of Functional Starch-Based Films Incorporating Free or Microencapsulated Spent Black Tea Extract.

Antioxidant polyphenols in black tea residue are an underused source of bioactive compounds. Microencapsulation can turn them into a valuable functional ingredient for different food applications. This study investigated the potential of using spent black tea extract (SBT) as an active ingredient in food packaging. Free or microencapsulated forms of SBT, using a pectin–sodium caseinate mixture as a wall material, were incorporated in a cassava starch matrix and films developed by casting. The effect of incorporating SBT at different polyphenol contents (0.17% and 0.34%) on the structural, physical, and antioxidant properties of the films, the migration of active compounds into different food simulants and their performance at preventing lipid oxidation were evaluated. The results showed that adding free SBT modified the film structure by forming hydrogen bonds with starch, creating a less elastic film with antioxidant activity (173 and 587 µg(GAE)/g film). Incorporating microencapsulated SBT improved the mechanical properties of active films and preserved their antioxidant activity (276 and 627 µg(GAE)/g film). Encapsulates significantly enhanced the release of antioxidant polyphenols into both aqueous and fatty food simulants. Both types of active film exhibited better barrier properties against UV light and water vapour than the control starch film and delayed lipid oxidation up to 35 d. This study revealed that starch film incorporating microencapsulated SBT can be used as a functional food packaging to protect fatty foods from oxidation.

Comparative Assessment of Biogas Production Potential of the Most Abundant Agro-residues in Turkey

Recent energy policies promote energy generations from green resources to meet sustainability criteria. Since Turkey is one of the largest agricultural producers globally, it has great biogas production potential. This study aims to evaluate the biomethane yields of the most abundant agro-residues in Turkey and to assess their potentials for contribution to biogas production. Within this scope, sunflower heads, tea residues, cotton stalks, and crop residues; wheat, rye, and triticale straws were collected from different regions of Turkey. Anaerobic batch digesters were conducted to investigate the biomethane production of the selected feedstock and operated for 30 days at 37°C. Each setup was conducted in triplicates and methane productions were monitored online. The main methane production route of the inoculum was determined as acetoclastic methanogenesis while Cloacimonetes, Firmicutes, and Bacteroidetes composed the core bacterial phyla. The greatest methane yield was observed in the digesters operated with the wheat straw followed (164 NmL/gVSinfluent) by triticale straw and sunflower head. The lowest yields were calculated for the digesters fed with the cotton stalks (71 NmL/gVSinfluent). To increase the biomethane potential yields in the anaerobic digesters operated with agro-residues and to make the anaerobic digesters more feasible, operational conditions should be optimized and physico-chemical and biological pre-treatment techniques and/or bioaugmentation applications should be integrated into the systems.

Activation of persulfate by green nano-zero-valent iron-loaded biochar for the removal of p-nitrophenol: Performance, mechanism and variables effects

In this study, with the green tea extraction solution as a reducing agent and green tea residues as a raw material of biochar, green nano zero-valent iron biochar (G-nZVI-BC) was prepared with the green synthesis method and then combined with potassium persulfate to degrade p-nitrophenol in water. Compared with zero-valent iron-loaded biochar (C-nZVI-BC) prepared by the traditional chemical liquid phase synthesis method, G-nZVI-BC containing tea polyphenols further improved dispersibility of Fe0 on biochar, prevented nZVI agglomeration on BC, and promoted PNP degradation. The system constructed by G-nZVI-BC/PDS showed the high oxidation resistance than the C-nZVI-BC/PDS system, thus endowing the synthesis material with long-term reactivity. Both the radical pathway and non-radical pathways contributed to catalytic degradation and free radicals played a key role. The G-nZVI-BC/PDS system realized the good removal effect on PNP in the pH range of 3.06–9.23. The reusability of G-nZVI-BC and the PNP removal effect in water body conditions indicated that G-nZVI-BC had a good application prospect in the field of water treatment.

Preparation and Characterization of Cellulose Composite Hydrogels From Tea Residue and Single-Walled Carbon Nanotube Oxides and Its Potential Applications.

Hydrogels were prepared from tea cellulose with the addition of single-walled carbon nanotube oxides in 1-allyl-3-methylimidazolium chloride. Single-walled carbon nanotube oxides/tea cellulose hydrogels (TCH-SWNTs) were characterized by Fourier transform infrared, x-ray diffraction, texture profile analysis, and thermogravimetric analysis. The adsorption capacity of methylene blue using the prepared hydrogels was also investigated. The hydrogels exhibited greater thermal stability and intensive textural property with the addition of single-walled carbon nanotube oxides. Compared with undoped TCHs, the weight loss peak moved from 280 to 323°C, and the values of hardness, fracturability, gumminess, and resilience were 8.4, 5.3, 10.8, and 1.9, respectively, times higher than that of TCHs. As an absorbent of methylene blue, TCH-SWNTs accorded to a pseudo-second-order kinetic model, good adsorption capacity (13.8 mg/g), and good adsorption ratio (27.59%) and showed potential as a drug carrier.

Photoluminescence quenching of thermally treated waste-derived carbon dots for selective metal ion sensing

In the present study, carbon-dots (CDs) were derived from the thermal oxidation of an agricultural waste, bitter tea residue, to obtain different sp2/sp3 ratios and electronic structures for metal sensing. The CDs obtained from calcination at 700 °C exhibited the highest photoluminescence (PL) quantum yield (QY) of 11.8% among all the samples treated at different temperatures. These CDs had a high degree of graphitization, which resulted in a strong π-π* electron transition, and hence in a high QY. The strong photoluminescence of the CDs could be used to sense the metal ions Ag+, Sr2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, and Sn2+ by monitoring their PL intensity at an excitation wavelength of 320 nm. The metals inhibited the PL intensity in the order Ag+ > Fe2+, Fe3+, Ni2+ > Sr2+, Co2+, Cu2+, Sn2+, which demonstrated that the CDs exhibited high metal ion detection capability and selectivity. The detection of Fe3+ using CDs was performed in the range of 10–100 ppm with a LOD (limit of detection) value of 0.380 ppm. Theoretical calculations demonstrated that Ag+, Sr2+, and Sn2+ induced charge transfer excitation and that Fe2+ and Ni2+ induced d-d transitions via complexation with the sp2 clusters. The charge transfer excitation and d-d transitions hindered the π-π* transition of the sp2 clusters, leading to a quenching effect. On the other hand, Li+, Na+, and K+ ions did not alter the π-π* transition of the sp2 clusters, resulting in a negligible quenching effect. In summary, the oxidation level and electronic structure of CDs derived from bitter tea residue could be tailored, and the CDs were shown to be a facile, sustainable, and eco-friendly material for metal sensing.

Modification of tea residue dietary fiber by high-temperature cooking assisted enzymatic method: Structural, physicochemical and functional properties

The research aimed to assess the effects of high-temperature cooking assisted enzymatic method on the structural, physicochemical and functional properties of soluble dietary fiber (SDF) from tea residue (GM-SDF). Under the optimal extraction conditions obtained by response surface methodology, the GM-SDF yield was significantly higher than that of untreated tea residue (U-SDF). It could be found results showed that GM-SDF possessed more hydrophilic groups, higher crystallinity, as well as a looser and more complicated structure by FTIR, XRD and SEM analysis. Besides, the differences in monosaccharide composition and molecular weight between U-SDF and GM-SDF were observed. Additionally, physicochemical properties analysis showed that water holding capacity, oil holding capacity and water swelling capacity of GM-SDF increased by 73.1%, 57.2% and 81.8% than that of U-SDF, respectively. Moreover, compared with U-SDF, GM-SDF exhibited higher adsorption capacity of glucose, sodium cholate, cholesterol and capacity of delaying glucose diffusion and dialysis. Furthermore, the inhibitory effect of GM-SDF on α-amylase was similar to that of acarbose. To sum up, the study showed that high-temperature cooking assisted enzymatic method can effectively extract dietary fiber from tea residue and improve the physicochemical and functional properties, which possesses great potential for application in functional food.

NaOH-modified mesoporous biochar derived from tea residue for methylene Blue and Orange II removal

To enhance the adsorption capacity via increasing the pore filling, the exchangeable ions content and electrostatic interaction, a late-model NaOH modified tea biochar for MB and OR-II removal was prepared. The effects of pyrolysis temperature, mass ratio of NaOH/tea residue powder (TRP) and other operation parameters, such as initial pH of the solution, contact time, initial concentration of dyes and adsorbent dosage on OR-II and MB removal in aqueous solution were studied by batch adsorption experiment. The results showed that with 10% w/w NaOH/TRP and pyrolysis at 700℃, the maximum adsorption capacities of BH700-10 of 105.27 and 91.68 mg/g for 250 mg/L MB and OR-II at pH10 or 2, respectively, were observed at 60 min. The adsorption isotherms of MB were in accordance with Langmuir and Sips models while the adsorption of OR-II was better described by the Freundlich model. The pseudo-second-order kinetic model could better describe the adsorption process. The possible interactions involved in the adsorption process was proposed. The results of this study indicated that BH700-10 is a promising low-cost adsorbent in dye wastewater treatment.

Hybrid multi-criteria decision-making approach to select appropriate biomass resources for biofuel production

Biofuel generation from local biomass resources can significantly contribute to greenhouse gas mitigation and cleaner energy production. In this regard, a hybrid Multi-Criteria Decision-Making (MCDM) approach was employed to prioritize appropriate biomass resources for biofuel production. Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), Additive Ratio Assessment (ARAS), and Weighted Aggregates Sum Product Assessment (WASPAS) were the employed MCDM approaches. Subsequently, ranking aggregation methods, i.e., Borda, Copeland, and Rank Mean, were applied to integrate the rankings obtained from the MCDM approaches. Guilan province of Iran was selected as a case study based on its promising potential for biofuel production from first-, second-, and third-generation biofuel resources. Initially, through an in-depth review of the literature and the use of academic professors' expert opinions, ten criteria were selected as the evaluation indices of the study: 1) creating technical side jobs, 2) preserving non-renewable energy resources, 3) relative advantage of biofuel production, 4) complexity of biofuel production process, 5) cost of the biomass conversion process, 6) biomass reusability, 7) cost of biomass supply, 8) environmental impacts of biomass accumulation, 9) adaptability of the biofuel production process to the size of biomass production units and the attitude and knowledge of the producers, and 10) energy self-sufficiency of the biomass producer. Moreover, the 11 investigated potential sources of biofuel production were rice, peanut, livestock and poultry wastes, rice waste, peanut waste, tea residues and its processing wastes, olive residues and its processing wastes, livestock and poultry slaughter and farm-raised fish wastes, municipal solid waste and sewage, forest and wood farming wastes, algae and Azolla. The results indicated that “municipal solid wastes and sewage”, “forest and wood farming wastes” and “livestock and poultry wastes” from the second-generation biofuels were identified as the most important biomass resources in the studied area.

Earthworm biomass and population structure are negatively associated with changes in organic residue nitrogen concentration during vermicomposting

Vermicomposting is an efficient and environmentally friendly technology to dispose of agricultural organic residues. The efficiency of organic residue decomposition during vermicomposting is directly affected by the biomass and population structure of earthworms. In this study, we investigated how the earthworm biomass and population structure responded to changes in the physicochemical properties of six types of organic residue (cattle dung, herbal waste, rice straw, soybean straw, garden waste, and tea residues) during vermicomposting. Each type of organic residues was placed in a pot with earthworms Eisenia fetida, and the physicochemical properties of the organic residues and earthworm growth dynamics were recorded at 0, 30, 60, and 90 d of vermicomposting. The biomass and population structure of earthworms were stable or increased in rice straw, garden waste, and cattle dung within 60 d of vermicomposting, whereas in tea residues and herb waste, very little earthworm activity (3 adults and 2 cocoons) was recorded on day 30. Among the physicochemical parameters, the substrate C/N ratio was negatively correlated with earthworm growth dynamics. Decomposing organic residues showed higher NH4+ -N and NO3– -N concentrations but a lower total organic carbon content, which negatively affected earthworm growth and reproduction. We recommend that chemical properties of vermicomposting systems should be monitored regularly. At the threshold levels of decomposing organic residue NH4+ -N and NO3– -N concentrations, earthworms should be removed and the vermicompost can be harvested. Small- and large-scale farmers thus need to monitor the physicochemical properties of vermicompost to sustain active earthworm populations.

Influence of the Carbonization Conditions on Propertiesof Tea Residue

Abstract The effects of carbonization temperature on some physicochemical properties of tea residue to evaluating the influence of the carbonization process and the product properties. The tea residue material was heated in laboratory conditions, the consequence of heat treatment at a specific temperature over the range 100-500°C was investigated by several techniques including the Transform Infrared (FTIR) Spectroscopy to study the functional groups, the chemical compositions of the sample were also investigated by Energy Dispersive X-Ray Fluorescence (EDXRF) Spectroscopy and the crystal structure was determined by X-Ray Diffraction (XRD). The spectrum of FTIR can be concluded that the number of functional group component of, O-H, C-H, C=O, and C-O respectively. On the other hand, for the result of EDXRF shown the trace elemental composition of composed of the organic compound (CHO). For the physical characteristic determination of the results of XRD, it indicated that mixture phase and a lot of crystalline in the specimen after heat treatment

Effects of different extractions on growth and nutritional quality of hydroponic endivia

In this study, Hydroponic endivia with completely decomposed distiller’s grains, tea residue and extraction of commercial organic manure were applied to study its effects on growth and nutritional quality of endivia, as compared with modified Hoagland nutrient. The results showed that the root-shoot ratio of endivia under all treatment conditions was higher than that in CK group. Among them, treatment Ⅳ exhibited best improve efficiency; the treatment of Ⅰ, Ⅱ, Ⅴ, Ⅵ were beneficial to reduce the nitrate content. The treatment Ⅰ significantly increased the content of VC and soluble sugar. The soluble protein content of treatment Ⅴ was the highest. Above all, the application of tea residue and commercial organic fertilizer extracts in the actual production of hydroponic lettuce needs further and deeper research.

Peroxymonosulfate activation by tea residue biochar loaded with Fe3O4 for the degradation of tetracycline hydrochloride: performance and reaction mechanism.

The recycling of agricultural and food waste is an effective way to reduce resource waste and ameliorate the shortage of natural resources. The treatment of antibiotic wastewater is a current research hotspot. In this study, waste tea residue was used as a raw material to prepare biochar (T-BC) and loaded with Fe3O4 as a catalyst to activate peroxymonosulfate (PMS) for oxidative degradation of tetracycline hydrochloride (TCH). Analysis techniques such as BET, SEM, XRD, FT-IR, XPS and VSM indicated that the heterogeneous catalyst (Fe3O4@T-BC) with good surface properties and magnetic properties was successfully prepared. The results of batch-scale experiments illustrated that when the dose of the Fe3O4@T-BC catalyst was 1 g L−1, the concentration of PMS was 1 g L−1, and the initial pH was 7, the degradation rate of TCH with a concentration of 50 mg L−1 reached 97.89% after 60 minutes of reaction. When the initial pH was 11, the degradation rate of TCH reached 99.86%. After the catalyst was recycled four times using an external magnet, the degradation rate of TCH could still reach 71.32%. The data of removal of TCH could be best fitted by a pseudo-first-order model. The analysis of the degradation mechanism through a free radical quenching experiment and EPR analysis, as well as the exploration of TCH intermediate products and reaction paths through the LC-MS method, all confirmed that the Fe3O4@T-BC prepared by this method is expected to become a cost-effective and environmentally friendly heterogeneous catalyst for activating persulfate degradation of tetracycline antibiotics.

Using spent tea residue to elimination of chromium in aqueous liquid

In this work, spent red and black tea form leaves were assessed for their ability to doff expel chromium ion from aqueous solutions at various values of PH. Classification adsorption experiments indebted at choice temperature and showed cruise the adsorption of Cr ion decrease more the increase of temperature. In successive lyrics, the adsorption fight is exothermic and the enthalpy is fatal, at long last the unconventional ways and the entropy are positive. The matter copied at equal stat was compared with Langmuir, Freundlich models, and the inference efficiencies for Cr ion higher than 99% and can easily be achieved. It was hinge saunter the brilliant hatch is reform than hyacinthine cause in adsorption of chromium ion.

Phosphoric acid-treated Spent Tea Residue Biochar for Wastewater Decoloring: Batch Adsorption Study and Process Intensification using Multivariate Data-based Optimization

This work investigates the production of biochars from phosphoric acid-treated spent-tea residue (STR) by pyrolysis at different temperatures. The biochar morphology and chemistry were characterized via SEM, FT-IR, XRD and BET analyses. Results showed that an increase in the pyrolysis temperature could enhance the porous-structure and increase the surface area, whereas it might deteriorate the surface-functional groups to some extent. The produced biochar samples were employed for the adsorption of methylene blue (MB) from water. The batch adsorption process was investigated via a data-based multivariate optimization approach, Pareto sensitivity analysis and response surface methodology (RSM) for the intensification of the process. The STR biochar produced at the pyrolysis temperature of 400 °C offered the maximum MB removal of 99.26% at the optimal operating conditions of pH = 9.65, initial dye concentration = 81.24 mg/L, adsorbent dosage = 0.26 g and contact time = 97.92 min. Pareto sensitivity analysis revealed that the MB adsorption on STR-derived biochar is strongly influenced by pH and contact time. The isothermal and kinetic studies indicated that the adsorption of MB on STR biochar is well described by the Langmuir isotherm and pseudo-second order model, respectively. The adsorption capacity of the optimal biochar was obtained to be 91.13 mg/g.

Reverse microemulsion prepared by AOT/CTAB/SDS/Tween80 for extraction of tea residues protein

The work attempted to study a new method for tea residue protein extraction. In this study, three kinds of microemulsion systems were constructed and their phase behaviors were investigated and compared. The conductivity, viscosity, surface tension and particle size were used to characterize the reverse microemulsion. Then, three kinds of microemulsion systems were used to extract tea residues protein. Based on the results of tea residues protein extraction yield with orthogonal optimization, CTAB-Tween80 microemulsion was more robust to extract protein, and the tea residues protein extraction yield could reach 42.1%. This study indicated that the CTAB-Tween80 reverse microemulsion has the potential ability to extract the tea residue protein.

Utilization of tea residue for coloration of wool/acrylic blended yarn

Natural dyeing has regained its popularity in order to keep the environment clean and safe by reducing the use of harmful chemicals in the dyeing process. Consequently, different natural dyestuff has been used in textile coloration: marigold, henna, onion skin, roots, and tree bark. Among these dyestuffs, tea has been used for the coloration of textiles. Around the world, including Bangladesh, a lot of tea is consumed on a daily basis. After consumption, the tea residue is disposed of in open spaces, which is considered a source of environmental pollution. Due to the adverse effect on the environment, this experiment used tea residue to dye wool/acrylic blended yarn to make the dyeing process more eco-friendly. Four different mordanting agents were used to determine the one most suitable for dyeing wool/acrylic blended yarn using tea residue. To evaluate the performance of the dyed yarn, the color-coordinate value and different colorfastness properties were measured.

Effects of fermentation on the structural characteristics and in vitro binding capacity of soluble dietary fiber from tea residues

The effects of Trichoderma viride fermentation treatment on the structural characteristics and in vitro binding capacity of three heavy metal ions (Pb, Cd, Cu) of soluble dietary fiber (SDF) from tea residues were investigated. Compared with the yield of SDF from untreated tea residues (U-SDF), that of fermented tea residues (F-SDF) significantly increased from 4.3% to 31.56% under the optimal conditions by using response surface methodology. The F-SDF exhibited higher uronic acid content (34.82% vs 17.81%), crystallinity (23.11% vs 17.36%) and thermal stability than U-SDF. Moreover, the specific surface area of F-SDF increased after fermentation by SEM analysis. Difference appeared in the monosaccharide composition ratio of F-SDF (0.06:0.77:1.00:2.41:0.63:0.86:1.80) and U-SDF (0.02:0.81:1.00:0.34:0.13:1.39). Furthermore, the binding capacity of SDF for Pb, Cd, and Cu at pH 7.0 were more than 2.4 times than that at pH 2.0. The binding capacity of F-SDF for Pb (664.5 vs 590.7 μmol/g), Cd (405.6 vs 349.6 μmol/g), and Cu (368.5 vs 307.9 μmol/g) were significantly increased than U-SDF. The overall results indicated that F-SDF could be used as a potential food additive to protect the body from the hazard of food-derived heavy metals.

Laccase production by Trametes versicolor in solid-state fermentation using tea residues as substrate and its application in dye decolorization

An efficient valorization of tea residues into value-added product was developed by Trametes versicolor in solid-state fermentation (SSF). The laccase production of 25.7 U/g dry substrate was obtained by optimizing culture medium and condition, resulting in a 4.0-fold increase compared to that of 6.4 U/g dry substrate under unoptimized condition. During the 7-day cultivation under SSF, 44.7%, 12.2% and 9.8% degradation occurred for lignin, hemicellulose and cellulose in tea residues, respectively. Laccase production reached 31.2 U/g dry substrate by the scaling-up culture in shallow tray system. The dry fermented tea residues were directly used as crude enzyme in the decolorization of malachite green. It possessed a decolorization rate of more than 95% within 120 min and remained 81.3% of decolorization capacity after 6 cycles. The present study provided a useful strategy for low-cost laccase production by SSF and it exhibited great potential for the application in dye decolorization.

Effects of Fermented Herbal Tea Residues on the Intestinal Microbiota Characteristics of Holstein Heifers Under Heat Stress

Herbal tea residue (HTR) is a reusable resource with high nutritional value and bioactive substances content, which can be used as a feed additive. In the present study, HTRs were fermented by lactic acid bacteria, and then fed to a total of 90 Holstein heifers, termed as CN, LC, and HC groups. The supplementation improved physiological indices of respiratory frequency and rectal temperature, increased the concentrations of immunoglobulins and antioxidant capacity-related parameters, and reduced the concentrations of heat stress-related parameters and serum hormones. The heifers’ body height increased considerably, while their energy metabolism rates were stimulated in response to fermented HTRs. We also studied the fecal microbial community composition of 8 Holstein heifers in each group, and employed correlation analysis with tested parameters. We found that the bacteria were closely related to characteristics including the energy utilization rate, growth performance, serum biochemical indexes, and fecal SCFA levels of the heifers. Based on our findings, the 5% fermented HTRs replaced corn silage might be advantageous for the heifers’ characteristics under heat stress.

Use of wastes from the tea and coffee industries for the production of cellulases using fungi isolated from the Western Ghats of India

In this study, coffee pulp (Coffea arabica) and green tea (Camellia sinensis) residues were characterized for use as a substrate of solid-state fermentation for cellulases production. The invasion rate was evaluated, as well as cellulases production by strains of Aspergillus niger and Trichoderma asperellum from the western Ghats of India, on coffee pulp, green tea, and a mixture of both substrates (50:50). T. asperellum (AFP) strain was found to have the highest growth rate (0.409 ± 0.021 mm/h) using a mixture of both substrates. The production of cellulases by T. asperellum was unsatisfactory due to the presence of polyphenols in the supports to which A. nigger cellulases are more resistant. The production of cellulases by A. nigger was linked to the pH of the supports, favouring the use of T and TC. It was found that the extracts produced by A. niger (28A strain using a mixture substrate, 28A, and 20A strains using only green tea as a substrate) presented the highest cellulase activities when evaluated using a plate technique producing degradation halos of 2.3 ± 0.1 cm of diameter. Aspergillus 28A strain did not require mineral enrichment media for cellulase production using green tea residues as support of solid-state fermentation.