Faculty Publications
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Item Enhancing gallic acid content in green tea extract by using novel cell-associated tannase of Bacillus massiliensis(2013) Palabhanvi, B.; Belur, P.D.Gallic acid content in green tea extract was enhanced by using a novel cell-associated tannase of Bacillus massiliensis. Biomass that contains tannase was used for this study. The activity of the cell-associated tannase was stable during 1 week of storage in the refrigerator. Response surface methodology was applied based on central composite design to determine the effects of three independent variables (pH, temperature and incubation time) and their mutual interactions. A total of 16 experiments were conducted; and a statistical model was developed, which predicted 475.74mg/L gallic acid production at pH6.2, 36C and incubation period of 16.71h. The subsequent verification experiments confirmed the validity of the model. Under optimal conditions, 84.7% of the total hydrolyzable tannins were converted to gallic acid and glucose. This naturally immobilized tannase was stable enough to be used for up to 12 runs. Practical Applications: The current study shows that naturally immobilized tannase of Bacillus massiliensis can be used instead of artificially immobilized tannase. Such naturally immobilized tannase has many advantages as it avoids expensive and laborious isolation, purification and immobilization. Ease of separation of cell-associated enzyme from the reaction mixture and absence of any detectable extracellular tannase activity after enzymatic treatment are some of the encouraging facts. Stability during storage up to 7 days, 85% tannic acid hydrolyzing efficiency, activity at pH3.5-8.0 and operational stability for 12 runs are some of the interesting features of this naturally immobilized enzyme. However, its application for tea treatment will be limited until Bacillus massiliensis gets "Generally Recognized As Safe" status. It can be employed, however, for production of gallic acid from agro residues and production of propyl gallate. © 2012 Wiley Periodicals, Inc.Item Lipase mediated synthesis of rutin fatty ester: Study of its process parameters and solvent polarity(Elsevier Ltd, 2017) Chandrasekar, C.; Belur, P.D.; Iyyaswami, R.Lipophilization of antioxidants is recognized as an effective strategy to enhance solubility and thus effectiveness in lipid based food. In this study, an effort was made to optimize rutin fatty ester synthesis in two different solvent systems to understand the influence of reaction system hydrophobicity on the optimum conditions using immobilised Candida antartica lipase. Under unoptimized conditions, 52.14% and 13.02% conversion was achieved in acetone and tert-butanol solvent systems, respectively. Among all the process parameters, water activity of the system was found to show highest influence on the conversion in each reaction system. In the presence of molecular sieves, the ester production increased to 62.9% in tert-butanol system, unlike acetone system. Under optimal conditions, conversion increased to 60.74% and 65.73% in acetone and tert-butanol system, respectively. This study shows, maintaining optimal water activity is crucial in reaction systems having polar solvents compared to more non-polar solvents. © 2017 Elsevier LtdItem Selective encapsulation of quercetin from dry onion peel crude extract in reassembled casein particles(Institution of Chemical Engineers, 2019) Ghatak, D.; Iyyaswami, R.Quercetin, a lipophilic dietary flavonoid, used as a therapeutic agent and a food component was encapsulated with casein particles to improve its water solubility as well as bioavailability in the food and pharmaceutical formulations. The nano-structured casein particles were reassembled with pure quercetin from the synthetic solution and the encapsulation yield was assessed by studying the effect of pH and the concentration of casein and additives like salts and Cetyl trimethylammonium bromide (CTAB). A maximum encapsulation yield of 97% was obtained for the reassembled casein particles formed with the addition of 0.5% (w/v) sodium caseinate, 0.1 M of calcium chloride, 0.5 M of di potassium hydrogen phosphate, 0.1 mM CTAB and 1 M of sodium citrate at a pH of 7. The identified process condition was further used to encapsulate the quercetin from the aqueous crude extract of dried onion peels. The microwave-assisted extraction was able to produce the crude extract with maximum quercetin content of 39.37 ?M per ml of the extract. Further the response surface methodology (RSM) was used to optimize the significant encapsulation variables for the maximum encapsulation yield of quercetin from aqueous crude extract. A maximum encapsulation yield of 96% was achieved at the pH 7.09 by using 2.1% (w/v) of sodium caseinate. © 2019 Institution of Chemical EngineersItem Exploring the potential role of quercetin in corrosion inhibition of aluminium alloy 6063 in hydrochloric acid solution by experimental and theoretical studies(Taylor and Francis Ltd., 2022) Kumari, D.; Venugopal, P.P.; Reena Kumari, P.D.; Chakraborty, D.Quercetin was evaluated as corrosion inhibitor for AA6063 in 0.5 M HCl solution by employing weight-loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Analysis (EDX), Atomic Force Microscopy (AFM), X-Ray photoelectron spectroscopy (XPS) techniques allied to quantum chemical studies. Electrochemical results substantiate that the inhibition efficacy of quercetin increases proportionally with the concentration of the inhibitor. The effect of temperature on the corrosion behavior of the alloy was studied in the range of 30–60 °C. Potentiodynamic polarization study confirms the mixed type of inhibition by quercetin with preferential control of the cathodic reaction. The adsorption of quercetin on alloy surface was explained through the Langmuir adsorption isotherm model. ΔG°ads values and its variation with the temperature ensured spontaneous adsorption through chemisorption and the process was endothermic. Further, quantum chemical parameters calculated from Density Functional Theory (DFT) method for quercetin, proved a perfect correlation between structure and corrosion inhibition efficiency. © 2021 Informa UK Limited, trading as Taylor & Francis Group.Item Comparison of efficacy of various natural and synthetic antioxidants in stabilizing the fish oil(John Wiley and Sons Inc, 2022) Mishra, S.K.; Belur, P.D.; Iyyaswami, R.Use of antioxidants (natural and synthetic) can retard oxidative degradation of fish oil having n-3 PUFA. The performance of each antioxidant is found to be affected by the composition of the oil, presence of impurities and storage condition. Hence an attempt was made to find the efficacy of catechin, resveratrol, β-carotene, caffeic acid, sinapic acid, ellagic acid, ferulic acid, vanillic acid, quercetin, rutin, TBHQ, BHA, and BHT at a concentration of 0.9 mM in the bulk fish oil, stored for 50 days exposed to air at 25°C under darkness. The extent of primary and secondary oxidation of the stored oil was determined every 5 days and were compared. The efficacy of TBHQ followed by BHA and BHT was found to be highest among all the antioxidants studied. Among the natural antioxidants, resveratrol and catechin were found to exhibit superior efficacy, whereas β-carotene was found to exhibit proxidant behavior. Novelty impact statement: This is the first comprehensive study carried out to find the most effective antioxidant involving ten natural and three synthetic antioxidants in n-3 PUFA containing fish oil. TBHQ exhibited superior efficacy among all the antioxidants tested and at a concentration of 0.9 mM, the change in TOTOX value by the end of 40 days of storage was about 80%. None of the other antioxidants studied here, exhibited such superior stability. Among the natural antioxidants, resveratrol and catechin were found to be superior. © 2022 Wiley Periodicals LLC.Item Development of stable and functional encapsulated chrysin using casein–polysaccharide complexes for food applications(John Wiley and Sons Inc, 2023) Parappa, K.; Krishnapura, P.R.; Iyyaswami, R.; Belur, P.D.Chrysin is a hydrophobic flavonoid with multiple health benefits. The various applications of chrysin are challenged by its poor solubility, instability and loss of bioactivity. Casein–chrysin complex and casein–polysaccharide–chrysin complexes have developed to overcome these limitations. Very high encapsulation efficiency of 98.23 ± 0.22% was achieved with casein–inulin–chrysin complex. The chrysin was able to form a stable casein–polysaccharide–chrysin complex suspension with a hydrodynamic diameter of 382.3 nm, zeta potential value of −12.3 mV and a Polydispersity Index (PDI) of 27.7. The antioxidant activity of chrysin increased about threefold after encapsulation. The release of chrysin from its encapsulated complexes to different buffers in the pH range of 3 to 10 was studied at 1:10 ratio. At the end of 48 h, only 6%–8% of chrysin was released in the pH range 3–4, 33%–58% at pH 5–9 and 62% at pH 10. The chrysin encapsulated in casein–inulin–chrysin complex was able to overcome the rapid release of chrysin from the casein–chrysin complex. The results indicate the successful development of a stable encapsulated chrysin complex which can overcome the various limitations of chrysin in its potential applications. © 2023 Institute of Food, Science and Technology (IFSTTF).Item Extraction of chrysin from propolis and its selective encapsulation in synthetic/natural surfactant-based micelles(Taylor and Francis Ltd., 2024) Sivanesan, M.; Krishnapura, P.R.; Iyyaswami, R.; Parappa, K.; Belur, P.D.The encapsulation characteristics of chrysin (important flavonoid with potential food, pharmaceutical, and biomedical applications) was studied with nonionic surfactants Triton X-114 (TX) and Quillaja Saponin (QS), individually. The factors influencing the encapsulation efficiency (EE) of standard chrysin that is surfactant concentration, pH, NaCl concentration, and chrysin concentration were analyzed. The maximum EE of standard chrysin was found to be 98.23 ± 1.63% with TX micelles and 83 ± 2.31% with QS micelles under the following conditions: 0.02 mg/mL standard chrysin, 5% NaCl, pH 7, and 4% w/w TX 6% w/w QS. Selective extraction of chrysin from propolis was tried using three extraction techniques namely Maceration, Microwave-assisted Extraction (MAE), and Maceration with Microwave-assisted Extraction (MMAE). MAE, which gave a chrysin yield of 3 mg/g, was deemed the most suitable method for chrysin extraction from propolis. This MAE crude extract was subjected to encapsulation under the conditions previously optimized for standard chrysin. Specific encapsulation of chrysin from the propolis crude extract was achieved, with an EE of 92 ± 0.86% with TX and 84.97 ± 1.34% with QS. The encapsulated chrysin was characterized using particle size analysis and antioxidant activity. TX system was found to be the most suitable for the encapsulation, as it was able to selectively encapsulate chrysin from propolis, despite the presence of other interfering flavonoids in the crude extract. The microwave-assisted extraction combined with surfactant-based micellar encapsulation can be said to be an effective process for the extraction and encapsulation of chrysin from propolis. © 2023 Taylor & Francis Group, LLC.