Removal Of Tannins Research Articles

Kinetic Studies of Aspergillus ficuum Tannase Enzyme and its Application in Detannification of Grape Juice

This investigation was carried out to study the characterization and kinetics of the partially purified Aspergillus ficuum tannase enzyme for commercial scale application in the clarification and detannification of juices like grape. pH, temperature and optimum substrate concentration were determined for the tannase enzyme activity from Aspergillus ficuum. Also, the Crude and partial purified enzyme were tested for detannification grape juice quality characteristics. Results evidenced that it was found that the optimum partial purified tannase parameters were: temperature 50 oC, PH 5.5 and substrate concentration 1.6% as a tannic acidwith 6.155 specific activities of partial purified tannase enzyme with 225.46% relative activity higher than its control. The tannase enzyme showed a higher temperature and lower pH optima than the soluble enzyme and showed 81.61% and 66.36 % tannin removal from grape juice by crude enzyme and partial purified enzyme treatment, respectively at 37 oC, which has not been reported earlier. Also, maximum velocity of reaction (Vmax) and Michaeli’s constant (Km) values were 0.72 and 1.45 for partially purified tannase enzyme activity, respectively. Overall the quality of grape juice was better in partial pure tannase treated juice compared with untreated and crude enzyme treated juice. The present study exposed thatthis enzyme could demonstrate a valuable tool for a number of biotechnological applications. Also, the application of this enzyme on juice clarification also states that it can be employed in fruit juice processing for removal of tannin efficiently.

Disposable electrochemical microfluidic device for ultrasensitive detection of egg allergen in wine samples

Food allergies have been increasing all over the world. Egg is an important component in the food industries and the second most common cause of food allergy, shortly after milk. In the wine industry, egg white is applied as a fining agent for tannin removal. In this study, a sandwich-based immunoassay for ultrasensitive detection of ovalbumin (OVA) in wine samples was developed. The assay involves the use of magnetic beads (MBs) decorated with a polyclonal anti-OVA antibody (Ab2) and horseradish peroxidase (HRP), used as label for the quantification in a disposable electrochemical microfluidic device (DEμD) here developed. The Ab2-MB-HRP prepared was applied to capture, separate, and pre-concentrate OVA from wine samples. In the DEμD, OVA was immune-magnetically captured (OVA-Ab2-MB-HRP), producing a sandwich structure (GO-Ab1-OVA-Ab2-MB-HRP) on the electrode's surface. This arrangement results in an ultrasensitive device, achieving the ultralow limit of detection of 0.2 fg mL−1 OVA. Five samples of wines were analyzed by using the immuno-magneto-assay which presents excellent accuracy compared with enzyme-linked immunosorbent assay (ELISA).

Inhibitory Activity of β-lactamases by Hydro-Ethanolic Extracts of Harungana madagascariensis, a Plant of the Ivorian Pharmacopoeia

Infection due to multi-resistant bacteria is a public health concern. Unfortunately, the prospect of developing new antibiotics seem not to be on the horizon. Faced with this impasse, medicinal plants could be an alternative for the development of new molecules. The aim of this study was to determine the inhibitory effect of H. madagascariensis extracts on β-lactamases. Extraction of bioactive compounds from trunk barks and leaves of the plant was done in an ethanol-water mixture (70:30). Anti-β-lactamase activity was evaluated by spectrophotometry after the removal of tannins and a phytochemical screening was used to identify the groups of compounds. Concentrations inhibiting 50% of enzyme activity were 0.005±0.001 mg/mL (CTX-M-15), 0.01±0.001 mg/mL (P99) and 0.027±0.009 mg/mL (NDM-1) for bark extracts and 0.704 mg/mL for leaves extracts. Phytochemical screening revealed the presence of flavonoids in bark extracts. The ethanolic extracts of the trunk bark exert a good inhibitory activity on CTX-M-15, P99 and NDM-1 β-lactamases and this activity could be attributed to the presence of the flavonoids. Further studies by bio-guided fractionation of the ethanolic extracts of the bark could yield fractions with high inhibitory potential of β-lactamases.

Formation of Photocatalytically Active Titania on Mesoporous Silica with Silver Nanoparticles Synthesized Using Tannin as a Template and a Reductant

Monolithic, optically transparent silica was synthesized for the first time by a green-chemistry method using tannin as a template. Silver nanoparticles were produced in silica mesopores by the reduction by the remaining tannin. After the removal of tannin, silica was coated with titania, which was transformed into anatase by annealing at 500°C. The obtained nanocomposite demonstrated high photocatalytic activity, which was enhanced by the combination of titania and nanosized silver.

Synthesis, Characterization, Adsorption Isotherm, and Kinetic Study of Oil Palm Trunk-Derived Activated Carbon for Tannin Removal from Aqueous Solution.

Oil palm trunk (OPT) represents one of the five main oil palm biomass wastes with high carbon content that can be economically converted to a large surface area, porous activated carbon (AC) adsorbent to treat palm oil mill effluent wastewater in Indonesia and Malaysia. In the first portion of this work, the design of the experiment was used to determine the optimum set of synthesis parameters required to maximize the iodine number of AC [i.e., Brunauer–Emmett–Teller (BET) specific surface area indicator] prepared from OPT via chemical activation route using H3PO4. The iodine numbers of AC and AC yield were probed as the impregnation ratio, the activation time, and the activation temperature were varied in the range of 0.28–3.47, 5.68–69.32 min, and 379–521 °C, respectively. An impregnation ratio of 2.29, an activation time of 6 min, and an activation temperature of 450 °C were identified as the optimum set of synthesis parameters. In the second portion of the work, the AC synthesized using the optimum parameters were then characterized and tested as an adsorbent for tannin. N2 sorption results revealed that the AC exhibits type IV isotherm, that is, contains micropores and mesopores and displays a relatively high BET specific surface area of 1657 m2 g–1. Adsorption equilibria isotherms for tannin adsorption onto the AC were collected at three different pH of 2, 4, and 6 and were nonlinearly fitted using Langmuir and Freundlich isotherm models, where the Langmuir isotherm gave better fitting than Freundlich. The higher adsorption capacity at lower pH can be explained in terms of the absence of electrostatic repulsion interaction between the AC surface and the tannic acid species as suggested by the point of zero charges (pHpzc) of 4.8 and an increasing ionization of tannic acid with pH rise between 4 and 7. Adsorption kinetics data were also obtained at four different pH of 2, 4, 6, and 8 where the nonlinear pseudo-first-order model best fitted the kinetic at pH of 2 and the nonlinear pseudo-second-order model represented the kinetic best at the remaining higher pH, which suggests that tannin adsorption onto AC occurred by physisorption at pH of 2 and by chemisorption at pH of 4, 6, and 8.

Effect of thermal and non-thermal processing on astringency reduction and nutrient retention in cashew apple fruit and its juice.

The present study is aimed at evaluating the effect of different processing techniques on astringency reduction, nutrient retention, and sensory attributes in cashew apple fruit and its juice. Astringency attribute was measured by tannin content, while nutrition profile by ascorbic acid, total sugars, and antioxidant activity. Hot water, steaming, and microwave were selected as the source of heat application for treating whole fruit, where the process variables were the temperature and exposure time. The non-thermal technique selected to treat juice was by using bio coagulants, i.e., dried okra pod and drumstick seed powder, where the independent parameters were concentration and settling time. The processes were optimized using a multivariate approach coupled with full factorial design. The obtained results indicated that samples, with 42.6% tannin removal, were rated as being the least astringent. The use of dried okra pod powder under optimal conditions (0.3% concentration, 0.5h settling time) was found to be the best in reducing astringency while retaining the nutrient and desirable sensory attributes. Maximum tannin removal (48.9 ± 1.6%) with minimum loss of ascorbic acid (8.1 ± 0.9%), total sugar (4.8 ± 0.5%) and antioxidant activity (11.1 ± 1.0) with high sensory score (92.7 ± 1.6%) was achieved with composite desirability of 0.85.

Studies on the effect of pre-treatment of vegetable tanning process wastewater prior to biological treatment

Abstract Vegetable tanning process is carried out by the tanning industry for making of thick leathers used in shoes, suitcases and wallets. The vegetable tanning process wastewater (VTW) contains tannins which are polyphenolic and recalcitrant. The present study was focused on Fenton’s oxidation (FO), ozonation (OZ) and Fenton’s oxidation followed by ozonation (FO + OZ) processes as pre-treatment for VTW. The optimized H2O2/COD ratio for FO was found to be 1.25 and the ozonation contact time was optimized as 30 min. The maximum removal of tannins observed for each pre-treatment was found to be 49.5 %, 27 % and 74.6 % for FO, OZ and FO + OZ, respectively. Fourier Transform – Infra Red (FT-IR) Spectroscopy and Electro Spray Ionization – Mass spectroscopy (ESI-MS) analysis were performed to confirm the breakdown of tannins after each pre-treatment. After pre-treatment, the samples were subjected to aerobic treatment and the process efficiency was evaluated in terms of Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD5) removal. The effect of pre-treatment prior to biological treatment was assessed with the help of Monod kinetics. The kinetic parameters and the cost estimates for each pre-treatment were explained in detail in the manuscript.

Removal of chlorophyll and tannins from Anthocleista schweinfurthii Gilg leaves by electrocoagulation using iron electrodes: optimization using response surface methodology

AbstractBACKGROUNDAn electrocoagulation process using iron electrodes was applied for chlorophyll and tannins removal from ethanol extract of aerial parts of Anthocleista schweinfurthii Gilg. A second‐order regression using Central Composite Design (CCD) was used to investigate the main effects of four independent variables, namely supporting electrolyte concentration (in g L−1), ethanol percentage (%), current intensity (in amps) and electrolysis time (in minutes) and their interactions. The chlorophyll removal (CR), total tannins content (TTC) and total phenols content (TPC) were analyzed using response surface methodology (RSM) and CCD. Crude and optimized extracts were characterized by UV‐visible spectrometry and Fourier‐transform infrared spectroscopy.RESULTSThe RSM model obtained from the present study (R2 > 0.95) showed a good fit which suggests a good correlation between the predicted values and experimental results of CR and tannins removal. Under optimized conditions (supporting electrolyte concentration 2.4 g L−1; ethanol percentage 67%; current intensity 0.4 A and electrolysis time 75 min), CR of 98.23% and TTC of 58.83% were achieved while remaining 91.21% of TPC.CONCLUSIONEthanol percentage, current intensity and electrolysis time influences positively CR, TTC and TPC. According to the results, electrocoagulation is an appropriate technique indicated for extracting secondary metabolites while reducing the risks associated with the use of organic solvents. © 2020 Society of Chemical Industry

Taste Correction and Safety Evaluation of Rhodiola Extraction

Objective To explore tannins removal of Rhodiola extraction and evaluate its safety. Method: Content of Tannins was treated with cheese, tannins removal was used by chitosan embedding, safety evaluation was tested by acute toxicity. The pharmacodynamics were detected by in vivo and in vitro antioxidant methods. Results: 20g/L Rhodiola extraction added 1g chitosan under 50°C embedding 2h, tannis was removed effectively and taste improved greatly. The results of acute toxicity tests in mice showed that the daily dose of 29.73 g was safe on the basis of 70kg adult weight. Antioxidant activity in vitro was evaluated by DPPH, super-oxide anion and hydroxyl radical scavenging assays showed at concentration of 0.1% indicated better results, while results in vivo showed at concentration of 1.2% decreased p53, p21 gene expression. Conclusion: A reasonable process for removing tannins from were determined Rhodiola extraction and taste of Rhodiola extraction is safe under the removal extraction technique. Results of antioxidant proved that Rhodiola extraction is effective.

Extract of Mangifera indica L. leaves may reduce biofilms of Staphylococcus spp. in stainless steel and teatcup rubbers.

Human ingestion of antimicrobial residues in dairy products is a problem of public health. In this study we evaluated antibacterial effectiveness of aqueous and ethanolic leaf extracts of Mangifera indica L. as a natural alternative for reduction of Staphylococcus spp. biofilms. Eight Staphylococcus spp. strains from cows with mastitis and the Staphylococcus aureus strain (ATCC 25923) were evaluated. High performance liquid chromatography indicated the presence of phenolic compounds in the aqueous extract. Agilent Technologies gas chromatography revealed the presence of phenolic compounds, carbohydrates, and gallic acid in ethanolic extract. The tannin contents were 2.27 ± 0.01 and 2.67 ± 0.01% for ethanolic extract and aqueous extract, respectively. Extracts were evaluated in agar diffusion test and the size of inhibition zones were compared. The ethanolic extract was the most effective, showing minimum inhibitory concentrations and minimum bactericidal concentrations between 1.8-7.5 and 15.1-45.3 mg/ml, respectively. After tannin removal, the extracts were less effective, indicating these secondary metabolites as one of the main antibacterial compounds. The ethanolic extract at 45.3 mg/ml reduced mature biofilms in teat rubber (average: 3.91 log reduction) and stainless steel (average: 3.87 log reduction) after 5 min of contact. The extracts of M. indica leaves represent natural alternatives against Staphylococcus spp. strains and the ethanolic extract shows potential as a natural sanitizer.

Effect of domestic processing and microwave heating on phenolic compounds and tannins in some oil seeds

Oilseeds contain different constituents with antioxidant activity especially phenolic compounds and tannins, this study was conducted to evaluate the possible effects of some domestic processes such as dehulling, soaking, ordinary and pressure cooking, germination, fermentation and microwave heating on the contents of phenolic compounds and tannins in some oilseeds. The data revealed that oil seeds could be considered as a rich source of oils and proteins. Phenolic compounds contents of raw oil seeds were; 978.4, 968.0, 862.75, 915.0 and 1063.4 mg/100 g, while, tannin contents were; 510.0, 490.0, 457.0, 457.0 and 440.0 mg/100 g on dry weight basis in peanut, sesame, soybean, safflower and sunflower, respectively. All processing treatments reduced the phenolic compounds except dehulling of sunflower seeds which was increased by 9.6%. Dehulling of oil seeds reduced tannin content by 9-26.5%, while during cooking processes, tannin leaching out in cooking water resulted in a reduction in its content by 4.5-19.6% for ordinary cooking and 5.2-20.2% for pressure cooking. Germination and fermentation processes decreased tannin by 12.5-34.7 and 13.6-49.0%, respectively. Microwave heating treatment had an effect in removal of tannins from seeds than other cooking methods. The reduction ranged between 8.8-24.4% of its initial content in raw oil seeds. The study concluded that all processing treatments used in the study had an effect on the oilseeds content from both phenolic compounds and tannins.

The role of cosubstrate and mixing on fungal biofilm efficiency in the removal of tannins

ABSTRACT Tannins are polyphenolic compounds produced by plants and they are used in industrial vegetable tanning of leather. Tannins represent one of the low biodegradability substances in tannery wastewaters with high recalcitrant soluble chemical oxygen demand, furthermore high concentration of tannins can inhibit biological treatment. In the present study, four novel rotating submerged packed bed reactors were inoculated with a selected fungal strain to reach a biological degradation of tannins in non-sterile conditions. The selected fungal strain, Aspergillus tubingensis MUT 990, was immobilised in polyurethane foam cubes carriers and inserted inside a submerged rotating cage reactors. The reactors were feed with a solution composed of four tannins: Quebracho (Schinopsis spp.), Wattle (Mimosa spp.), Chestnut (Castanea spp.) and Tara (Caesalpinia spp.). Four reactors with a volume of 4 L each were used, the co-substrate was pure malt extract, the hydraulic retention time was 24 h and the pH setpoint was 5.5. The reactors configuration was chosen to allow the study of the effect of rotation and the co-substrate addition on tannins removal. The experiment lasted two months and it was achieved 80% of chemical oxygen demand and up to 90% dissolved organic carbon removal, furthermore it was detected an important tannase activity.

The Antidiabetic Effectivity of Indonesian Plants Extracts via DPP-IV Inhibitory Mechanism

: Background: Nature provides a rich source of antidiabetic medicines. More than 1.200 plants have been reported to have anti-diabetic activities and more than half of the drugs on the market come from natural products. Therefore, research for developing new antidiabetic drugs from natural sources is necessary to properly evaluate various mechanism of action, efficacy and safety at toxicological, physiological, pharmacological and molecular levels before these drugs applied in treatment of diabetes. This study aims to examine and determine the highest activity of 10 ethanol extracts from Indonesian plants selected for in vitro inhibitory activity of dipeptidyl peptidase – IV (DPP-IV). Materials and Methods: This research studied DPP-IV inhibitory mechanism from 10 plant extract, namely Caesalpinia sappan, Cinchona officinalis, Elephantopus scaber, Foeniculum vulgare, Morus nigra, Muntingia calabura, Phyllanthus niruri, Psidium guajava, Rheum palmatum and Vernonia amygdalina using the spectrophotometric method and Sitagliptin as a positive control. The effectiveness of inhibition was assessed by percent inhibition. Tannin removal test was performed to exclude false-positive results. Results: The ethanolic extract of Caesalpinia sappan exhibited DPP-IV inhibitory activity greater than 80%, which was not markedly different from that of Sitagliptin at 85%. Brazilin, an active compound from Caesalpinia sappan gave the inhibition at greater than 78%. Tannin removal test for Caesalpinia sappan gave the inhibition at 74.16%. The High Performance Liquid Chromatography (HPLC) analysis result displayed that brazilin content on Caesalpinia sappan extract was 91.94%. Conclusion: Based on these results, Caesalpinia sappan ethanol extract has a potential effect as a better antidiabetic agent than other extracts used in this study.Key words: Antidiabetic, DPP-IV, Caesalpinia sappan, Inhibitory activity.

Anthelmintic activity of Annona crassiflora leaves against Haemonchus contortus: part 1: in vitro inhibition of the hatchability and larval development

We evaluated the activity of Annona crassiflora leaves against Haemonchus contortus resistant to albendazol. Aqueous (AE), ethanolic (EE) and ethyl acetate (EAE) extracts were produced and the predominant presence of flavonoids was observed in HPLC-DAD chromatograms. Initially we evaluated the larval development inhibition (LDI) of dry A. crassiflora leaf powder or its AE directly in fecal quantitative cultures. The efficacies of the extracts, with or without tannins, on egg hatching inhibition (EHI) were investigated reveling that the EE was the most effective (LC90 = 8.96 mg/mL). However, after tannin removal, AE showed the highest activity (LC90 = 4.27 mg/mL). In the LDI test, the LC90 of AE was < 6.25 mg/g of fecal culture and to leaf powder of leaves was 69.14 mg/g. High efficacies of AE and EE for EHI were detected and the tannins were not the main active metabolites. The anthelmintic potential of this plant could be attributed to association between flavonoids and other metabolites.

Pilot study of magnetic nanoparticles via SuperPro simulation using catalytic hydrothermal carbonization process

Nanoparticles can be utilised in many field applications such as environmental analysis, water and wastewater treatment and medical treatment due to its unique physical and biomedical properties. Magnetic nanoparticles are excellent absorbent to treat large volumes of water or wastewater. Magnetic nanoparticles not just only have the same properties as nanoparticles, yet it has magnetic characteristic. Iron oxides magnetic nanoparticles react with different functional groups and ligands, which can achieve specific contaminants removal. Despite of that, magnetic nanoparticles are still not commercially available for water and wastewater treatment. Thus, this pilot study was conducted based on the most economical and feasible approach to produce magnetite (Fe3O4) nanoparticles. Magnetite (Fe3O4) nanoparticles are synthesized via Hydrothermal Carbonization (HTC) process using sugarcane bagasse as carbon precursor followed by 400 ℃ heat treatment for tannin removal but still retain its good magnetic property. This pilot study was carried out based on a production capacity of 5000 tonnes per annum magnetite (Fe3O4) nanoparticles with the least of 95% purity. Financial analysis for this pilot study was conducted. Total annualized cost for base case was rated to be USD $ 129,294,635 per annum. Total revenue for base case was estimated to be USD $4,452,949,096 with a payback period of 1.3 years. Net profit is USD $41,134,543 per annum with returned on investment (ROI) of 75% for base case. Thus, a plant scale-up is feasible for this pilot study.

Differential inhibition of digestive proteases by tannin in two size groups of rohu (Labeo rohita,Hamilton): A biochemical and zymography study

This study was intended to evaluate tannin mediated inhibition of digestive proteases in two different size groups (fingerlings, F, 4.5 ± 0.7 cm; advanced fingerlings, AF, 18.2 ± 1.6 cm) of rohu, Labeo rohita. Graded levels (50, 100, 150 and 200 nM) of tannin (Gallotannin, 99% purity) were added to the enzyme extracts (30°C, 1 hr) prior to determination of enzyme activities. Changes in the activity of trypsin, chymotrypsin and total protease in relation to the control sets were determined through biochemical assay of enzymes and SDS-PAGE zymography. The study revealed that tannin significantly inhibited trypsin, chymotrypsin and total protease activities in a dose dependent manner as evident from the regression equations. The degree of the inhibition appeared to be significantly higher for the F in contrast to the AF (F5,66 = 282.311; p < 0.0001). Trypsin activities were reduced by 8.04 ± 0.19% to 52.68 ± 0.72% and 5.61 ± 0.22% to 39.46 ± 0.19% in F and AF, respectively. The reduction in Chymotrypsin activities ranged between 16.11 ± 0.03% to 38.02 ± 0.27% in F and 6.31 ± 0.07% to 22.80 ± 0.32% in AF. Total protease activities were reduced by 10.9 ± 0.07% to 49.60 ± 0.32% in L. rohitaF, whereas, it ranged between 5.19 ± 0.06% to 32.60 ± 0.13% in AF. On a comparative scale, the difference in tannin induced inhibition in F and AF were more prominent for trypsin and chymotrypsin than total protease. Further, nine protease activity bands (15.9–69 kD) with different electromobility were noticed in both the size groups. Subsequent densitometry analysis revealed that the average densities of the protease activity bands were gradually decreased with increasing level of tannin exposure (50–200 nM). The study might indicate adaptive tolerance to tannin in larger size groups and emphasizes the need for removal of tannin in the plant feedstuffs, especially for feeding the fingerlings of L. rohita.

Removal of Quebracho and Tara tannins in fungal bioreactors: Performance and biofilm stability analysis

Tannins are polyphenolic compounds produced by plants that are used in the vegetable tanning of leather at industrial scale. Quebracho tannin and Tara tannin are intensively used by the tanning industry and are two of the most recalcitrant compounds that can be found in tannery wastewaters. In this study two reactors fed with Quebracho tannin and Tara tannin, respectively, were inoculated with polyurethane foam cubes colonized with a fungal strain biofilm of Aspergillus tubingensis MUT 990. A stable biofilm was maintained in the reactor fed with Quebracho tannin during 180 days of operation. Instead, biofilm got detached from the foam cubes during the start-up of the reactor fed with Tara tannin and a bacterial-based suspended culture was developed and preserved along the operational period (226 days). Soluble chemical oxygen demand removals up to 53% and 90% and maximum elimination capacities of 9.1 g sCOD m−3 h−1 and 37.9 g sCOD m−3 h−1 of Quebracho and Tara tannins, respectively, were achieved in the reactors without the addition of co-substrates. Next generation sequencing analysis for bacteria and fungi showed that a fungal consortium was developed in the reactor fed with Quebracho tannin while fungi were outcompeted by bacteria in the reactor fed with Tara tannin. Furthermore, Quebracho and Tara tannins were successfully co-treated in a single reactor where both fungi and bacteria were preserved.

A new method for simultaneous removal of heavy metals and harmful organics from rape seed meal from metal-contaminated farmland

Abstract Phytoremediation is a promising, cost-effective technique for remediating soil contaminated by heavy metals. When using this approach, however, much contaminated plant material will necessarily be generated that cannot be properly treated after the phytoextraction process. This remains an unsolved problem and thus a major hurdle for the commercial implementation of phytoremediation. This study’s main objective was to remove several heavy metals and harmful organics from rape seed meal via hydrochloric with 70% alcohol extraction under different experimentally controlled conditions, namely the extraction concentrations, the reaction time and temperature, and the extraction steps. Our results showed the following: (1) Removal of heavy metals was increased by raising the temperature, or extractant concentrations, or successive extraction steps. The highest extraction efficiency was attained with 1% hydrochloric acid at 25 °C for 12 h after three successive extractions; under this condition, the removal of Pb, Zn, Cu, and Cd, respectively, reached 89.1%, 93.9%, 92.3%, and 99.3%. (2) After three successive extractions using 0.5% hydrochloric acid, at 25 °C for 12 h, the concentrations of Cd and Pb in rape seed meal were 0.028 and 2.75 mg kg−1, respectively, which met the current Chinese feed safety standards. Thus, 0.5% hydrochloric acid for the extraction of heavy metals in rape seed meal is economically appropriate. (3) Extraction using hydrochloric acid left little harmful organics rape seed meal, but it little lowered the concentrations of six nutrient elements. The removal of phytic acid, tannins, and glucosinolates, respectively, reached 99.2%, 50.0%, and 85.6%. Importantly, crude protein content as a nutrient was reduced by just 1.4%. In general, hydrochloric extraction is a very thorough cost-benefit method for removing heavy metals from rape seed meal.

Evaluation and kinetic study on enzyme supplementation to biological treatment of vegetable tanning process wastewater

Vegetable tannins bind to the collagen of raw hides/skins and transform them into leather. The polyphenolic nature of tannin makes it inhibitory to the microorganisms and hinders the biodegradation process. Studies were carried out by external supplementation of tannase enzyme to enhance the biodegradability of tannins present in vegetable tanning process wastewater (VTW). Aerobic treatment studies were carried out for (1) VTW alone and (2) by external supplementation of tannase enzyme to VTW. The performance of the treatment process was assessed for biochemical oxygen demand (BOD5), chemical oxygen demand (COD) and tannin removal efficiencies, separately. The results indicated that the removal efficiencies of COD, BOD5 and tannin were 27%, 39% and 34.1%, respectively, for VTW alone and 51.4%, 63% and 57%, in case of tannase enzyme-supplemented VTW, for the same residence time of 24 h. Pyrogallol, which is a breakdown product of tannic acid, was found to be 324 mg/L in enzyme-supplemented reactor and 97 mg/L in reactor without tannase enzyme supplementation. Based on the experimental studies, biodegradation kinetic coefficients were derived. In the aerobic treatment process for the tannase enzyme-supplemented VTW, the values derived for maximum specific growth rate (µm), yield coefficient (Y), decay coefficient (Kd), Monod half-saturation constant (Ks) and substrate inhibition constant (Ki) were 0.068 h−1, 0.436, 0.015 h−1, 345 mg/L and 46 mg/L, respectively. The role of tannase enzyme supplementation in enhanced removal of tannin content during the aerobic treatment process was confirmed by FTIR and GC–MS analysis.

Effect of lactic acid bacteria fermentation on tannins removal in Xuan Mugua fruits

The present study was conducted for developing a new method to reduce the tannins content of Xuan Mugua fruits. Lactic acid bacteria fermentation-like incubation was explored as an efficient method to reduce the astringency of Mugua fruits by reducing tannins content. To ensure the efficient removal of tannins, the fermentation conditions were optimized such as temperature, time, and ratio of bacteria to Mugua. Bacteria were able to reduce 78% of the tannins content in Mugua under the optimized conditions as assessed by the methylcellulose perceptible tannins assay. Meanwhile, the active components including polysaccharides, triterpenes, and antioxidants of Mugua with bacterial incubation were also explored, which showed the significant decrease compared to non-fermented Mugua. However, the trend for flavor components was different. This research provides a natural method to solve the astringency problem of these fruits and it will extend their application in food industry.