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Tsapou EA, Drosou F, Koussissi E, Dimopoulou M, Dourtoglou T, Dourtoglou V. Addition of yogurt to wort for the production of spirits: Evaluation of the spirit aroma over a two-year period. J Food Sci 2020; 85:2069-2079. [PMID: 32602125 DOI: 10.1111/1750-3841.15309] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 05/11/2020] [Accepted: 05/12/2020] [Indexed: 11/28/2022]
Abstract
Triggered by the development of lactic acid bacteria (LAB) during the production of Scotch whisky, this study examined the influence of yeast and LAB inoculation on whisky flavor. Four new spirits were produced using the same process. LAB were added as a form of a Greek yogurt's live culture. In each category (barley and rye), one sample was fermented with Greek yogurt while the other was fermented without it. The spirits were matured and analyzed at five different points. Results from gas chromatography-mass spectrometry (GC-MS) analysis showed basic volatile compounds, along with some important extra compounds with yogurt culture. The most obvious differences were observed in the concentration of butanoic acid, a characteristic acid in spirits undergoing lactic acid fermentation: to identify esters such as ethyl butanoate, ethyl isobutanoate, isoamyl butanoate, and 2-phenylethyl butanoate, they are not typical compounds in whisky.
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Affiliation(s)
- Evangelia A Tsapou
- Department of Wine, Vine, and Beverage Sciences, School of Food Science, University of West Attica, Athens, Greece
| | - Fotini Drosou
- Department of Wine, Vine, and Beverage Sciences, School of Food Science, University of West Attica, Athens, Greece
| | - Elisabeth Koussissi
- Department of Wine, Vine, and Beverage Sciences, School of Food Science, University of West Attica, Athens, Greece
| | - Maria Dimopoulou
- Department of Wine, Vine, and Beverage Sciences, School of Food Science, University of West Attica, Athens, Greece
| | - Thalia Dourtoglou
- Department of Wine, Vine, and Beverage Sciences, School of Food Science, University of West Attica, Athens, Greece
| | - Vassilis Dourtoglou
- Department of Wine, Vine, and Beverage Sciences, School of Food Science, University of West Attica, Athens, Greece
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2
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Abdullah A, Abd Gani SS, Yun Hin TY, Haiyee ZA, Zaidan UH, Kassim MA, Effendi Halmi MI. Lipase-catalyzed synthesis of red pitaya ( Hylocereus polyrhizus) seed oil esters for cosmeceutical applications: process optimization using response surface methodology. RSC Adv 2019; 9:5599-5609. [PMID: 35515910 PMCID: PMC9060793 DOI: 10.1039/c8ra09418g] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 01/14/2019] [Indexed: 11/21/2022] Open
Abstract
Esters were synthesized via the alcoholysis of red pitaya seed oil with oleyl alcohol catalyzed by immobilized lipase, Lipozyme RM IM. The effects of synthesis parameters, including temperature, time, substrate molar ratio and enzyme loading, on the yield and productivity of esters were assessed using a central composite response surface design. The optimum yield and productivity were predicted to be about 80.00% and 0.58 mmol h-1, respectively, at a synthesis temperature of 50.5 °C, time of 4 h, substrate molar ratio of 3.4 : 1 and with 0.17 g of enzyme. Esters were synthesized under the optimum synthesis conditions; it was found that the average yield and productivity were 82.48 ± 4.57% and 0.62 ± 0.04 mmol h-1, respectively, revealing good correspondence with the predicted values. The main esters were oleyl linoleate, oleyl oleate, oleyl palmitate and oleyl stearate. The synthesized esters exhibited no irritancy effects and their physicochemical properties showed their suitability for use as cosmeceutical ingredients.
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Affiliation(s)
- Asiah Abdullah
- Department of Chemistry, Faculty of Science, Universiti Putra Malaysia43400 UPM SerdangSelangorMalaysia,Faculty of Applied Sciences, Universiti Teknologi MARA72500 Kuala PilahNegeri SembilanMalaysia
| | - Siti Salwa Abd Gani
- Department of Agriculture Technology, Faculty of Agriculture, Universiti Putra Malaysia43400 UPM SerdangSelangorMalaysia+60 389474945,Halal Products Research Institute, Universiti Putra Malaysia, Putra Infoport43400 UPM SerdangSelangorMalaysia
| | - Taufiq Yap Yun Hin
- Department of Chemistry, Faculty of Science, Universiti Putra Malaysia43400 UPM SerdangSelangorMalaysia
| | | | - Uswatun Hasanah Zaidan
- Halal Products Research Institute, Universiti Putra Malaysia, Putra Infoport43400 UPM SerdangSelangorMalaysia,Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia43400 UPM SerdangSelangorMalaysia
| | - Mohd Azlan Kassim
- Chemistry Department, Faculty of Science, University of Malaya50603 Kuala LumpurMalaysia,Research Centre for Carbon Dioxide and Utilisation, School of Science and Technology, Universiti Putra MalaysiaNo. 5, Jalan UniversitiBandar Sunway47500 SelangorMalaysia
| | - Mohd Izuan Effendi Halmi
- Department of Land Management, Faculty of Agriculture, Universiti Putra Malaysia43400 UPM SerdangSelangorMalaysia
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3
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Efficient biotechnological synthesis of flavor esters using a low-cost biocatalyst with immobilized Rhizomucor miehei lipase. Mol Biol Rep 2018; 46:597-608. [DOI: 10.1007/s11033-018-4514-z] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 11/21/2018] [Indexed: 12/23/2022]
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4
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Supercritical CO2 technology applied to the production of flavor ester compounds through lipase-catalyzed reaction: A review. J CO2 UTIL 2018. [DOI: 10.1016/j.jcou.2017.11.011] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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5
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Mei J, Feng F, Guo Q, Li Y, Wu Y. Evaluation of freeze-dried Tibetan kefir co-culture as a starter for production of Bod ljong cheese. Food Sci Biotechnol 2015. [DOI: 10.1007/s10068-015-0130-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Enzymatic synthesis of isoamyl butyrate catalyzed by immobilized lipase on poly-methacrylate particles: optimization, reusability and mass transfer studies. Bioprocess Biosyst Eng 2015; 38:1601-13. [PMID: 25935327 DOI: 10.1007/s00449-015-1402-y] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 04/14/2015] [Indexed: 02/05/2023]
Abstract
Isoamyl butyrate (banana flavor) was synthesized by esterification reaction of isoamyl alcohol and butyric acid in heptane medium. Immobilized Thermomyces lanuginosus lipase (TLL) prepared via physical adsorption on mesoporous poly-methacrylate particles (PMA) was used as biocatalyst. The factors that affect the esterification reaction were optimized by response surface methodology (RSM). Under optimal experimental conditions, maximum ester conversion percentage of 96.1 and 73.6% was reached after 50 and 90 min, respectively, for esterification reaction performed at equimolar ratio alcohol:acid at 500 and 2000 mM of each substrate. Under these experimental conditions, the esterification reaction was not controlled by external and intra-particle mass transfer effects. The product (isoamyl butyrate) was confirmed by proton nuclear magnetic resonance ((1)H NMR) spectroscopy. Reusability tests showed that the biocatalyst retained around 96 and 31% of its initial activity after eight successive esterification cycles performed at 500 and 2000 mM, respectively. The application of the biocatalyst prepared showed to be a promising strategy to catalyze flavor ester synthesis in a non-aqueous medium.
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8
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Dhake KP, Thakare DD, Bhanage BM. Lipase: A potential biocatalyst for the synthesis of valuable flavour and fragrance ester compounds. FLAVOUR FRAG J 2013. [DOI: 10.1002/ffj.3140] [Citation(s) in RCA: 117] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Kishor P. Dhake
- Department of Chemistry; Institute of Chemical Technology; Matunga; Mumbai; 400 019; India
| | - Dinesh D. Thakare
- Department of Chemistry; Institute of Chemical Technology; Matunga; Mumbai; 400 019; India
| | - Bhalchandra M. Bhanage
- Department of Chemistry; Institute of Chemical Technology; Matunga; Mumbai; 400 019; India
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Jin Z, Ntwali J, Han SY, Zheng SP, Lin Y. Production of flavor esters catalyzed by CALB-displaying Pichia pastoris whole-cells in a batch reactor. J Biotechnol 2012; 159:108-14. [DOI: 10.1016/j.jbiotec.2012.02.013] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 01/03/2012] [Accepted: 02/24/2012] [Indexed: 10/28/2022]
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10
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Damnjanović JJ, Žuža MG, Savanović JK, Bezbradica DI, Mijin DŽ, Bošković-Vragolović N, Knežević-Jugović ZD. Covalently immobilized lipase catalyzing high-yielding optimized geranyl butyrate synthesis in a batch and fluidized bed reactor. ACTA ACUST UNITED AC 2012. [DOI: 10.1016/j.molcatb.2011.11.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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11
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GüvenÇ A, Kapucu N, Bayraktar E, MehmetoĞLU Ü. Optimization of the enzymatic production of isoamyl acetate with novozym 435 from candida antarctica. CHEM ENG COMMUN 2010. [DOI: 10.1080/00986440302124] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Afife GüvenÇ
- a Faculty of Engineering, Department of Chemical Engineering , Ankara University , Ankara, Turkey
| | - Nurcan Kapucu
- a Faculty of Engineering, Department of Chemical Engineering , Ankara University , Ankara, Turkey
| | - Emine Bayraktar
- a Faculty of Engineering, Department of Chemical Engineering , Ankara University , Ankara, Turkey
| | - Ülkü MehmetoĞLU
- a Faculty of Engineering, Department of Chemical Engineering , Ankara University , Ankara, Turkey
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Kapucu N, Güvenç F, MehmetoĞLU Ü, Çalimli A, Kapucu H. Lipase catalyzed synthesis of oleyl oleate: Optimization by response surface methodology. CHEM ENG COMMUN 2010. [DOI: 10.1080/00986440302107] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Nurcan Kapucu
- a Faculty of Engineering, Chemical Engineering Department , Ankara University , Tandogˇan, Ankara, Turkey
| | - Fife Güvenç
- a Faculty of Engineering, Chemical Engineering Department , Ankara University , Tandogˇan, Ankara, Turkey
| | - Ülkü MehmetoĞLU
- a Faculty of Engineering, Chemical Engineering Department , Ankara University , Tandogˇan, Ankara, Turkey
| | - Ayla Çalimli
- a Faculty of Engineering, Chemical Engineering Department , Ankara University , Tandogˇan, Ankara, Turkey
| | - Hamdi Kapucu
- b Pak Gida Üretim ve Pazarlama , Izmit, Kocaeli, Turkey
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Rodrigues RC, Fernandez-Lafuente R. Lipase from Rhizomucor miehei as an industrial biocatalyst in chemical process. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.molcatb.2010.02.003] [Citation(s) in RCA: 171] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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14
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Synthesis of 4-nitrophenyl acetate using molecular sieve-immobilized lipase from Bacillus coagulans. J Ind Microbiol Biotechnol 2008; 36:401-7. [DOI: 10.1007/s10295-008-0510-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Accepted: 12/03/2008] [Indexed: 10/21/2022]
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15
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Güvenç A, Kapucu N, Kapucu H, Aydoğan Ö, Mehmetoğlu Ü. Enzymatic esterification of isoamyl alcohol obtained from fusel oil: Optimization by response surface methodolgy. Enzyme Microb Technol 2007. [DOI: 10.1016/j.enzmictec.2006.06.010] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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16
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17
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Rodriguez-Nogales JM, Roura E, Contreras E. Biosynthesis of ethyl butyrate using immobilized lipase: a statistical approach. Process Biochem 2005. [DOI: 10.1016/j.procbio.2003.11.049] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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18
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Manohar B, Divakar S. Applications of surface plots and statistical designs to selected lipase catalysed esterification reactions. Process Biochem 2004. [DOI: 10.1016/s0032-9592(03)00192-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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19
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Yu ZR, Chang SW, Wang HY, Shieh CJ. Study on synthesis parameters of lipase-catalyzed hexyl acetate in supercritical CO2
by response surface methodology. J AM OIL CHEM SOC 2003. [DOI: 10.1007/s11746-003-0666-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Zer-Ran Yu
- ; Department of Food Science; National Chiayi University; 300 Chia-yi Taiwan
| | - Shu-Wei Chang
- ; Institute of Bioscience and Biotechnology; National Taiwan Ocean University; 202 Keelung Taiwan
| | - Hao-Yu Wang
- Department of Bioindustry Technology; Dayeh University; 112 Shan-Jiau Rd., Da-Tsuen 515 Chang-Hua Taiwan
| | - Chwen-Jen Shieh
- Department of Bioindustry Technology; Dayeh University; 112 Shan-Jiau Rd., Da-Tsuen 515 Chang-Hua Taiwan
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Hari Krishna S, Karanth NG. LIPASES AND LIPASE-CATALYZED ESTERIFICATION REACTIONS IN NONAQUEOUS MEDIA. CATALYSIS REVIEWS-SCIENCE AND ENGINEERING 2002. [DOI: 10.1081/cr-120015481] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Abstract
The conventional notion that enzymes are only active in aqueous media has long been discarded, thanks to the numerous studies documenting enzyme activities in nonaqueous media, including pure organic solvents and supercritical fluids. Enzymatic reactions in nonaqueous solvents offer new possibilities for producing useful chemicals (emulsifiers, surfactants, wax esters, chiral drug molecules, biopolymers, peptides and proteins, modified fats and oils, structured lipids and flavor esters). The use of enzymes in both macro- and microaqueous systems has been investigated especially intensively in the last two decades. Although enzymes exhibit considerable activity in nonaqueous media, the activity is low compared to that in water. This observation has led to numerous studies to modify enzymes for specific purposes by various means including protein engineering. This review covers the historical developments, major technological advances and recent trends of enzyme catalysis in nonconventional media. A brief description of different classes of enzymes and their use in industry is provided with representative examples. Recent trends including use of novel solvent systems, role of water activity, stability issues, medium and biocatalyst engineering aspects have been discussed with examples. Special attention is given to protein engineering and directed evolution.
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Affiliation(s)
- Sajja Hari Krishna
- AK-Technische Chemie und Biotechnologie, Institut für Chemie und Biochemie, Universität Greifswald, Soldmannstrasse 16, D-17487 Greifswald, Germany.
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22
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Isolation of a Pseudomonas lipase produced in pure hydrocarbon substrate and its application in the synthesis of isoamyl acetate using membrane-immobilised lipase. Enzyme Microb Technol 2002. [DOI: 10.1016/s0141-0229(02)00191-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Altreuter DH, Dordick JS, Clark DS. Optimization of ion-paired lipase for non-aqueous media: acylation of doxorubicin based on surface models of fatty acid esterification. Enzyme Microb Technol 2002. [DOI: 10.1016/s0141-0229(02)00092-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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24
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Srivastava S, Modak J, Madras G. Enzymatic Synthesis of Flavors in Supercritical Carbon Dioxide. Ind Eng Chem Res 2002. [DOI: 10.1021/ie010651j] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Shireesh Srivastava
- Department of Chemical Engineering, Indian Institute of Science, Bangalore 560 012, India
| | - Jayant Modak
- Department of Chemical Engineering, Indian Institute of Science, Bangalore 560 012, India
| | - Giridhar Madras
- Department of Chemical Engineering, Indian Institute of Science, Bangalore 560 012, India
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Krishna SH, Srinivas ND, Raghavarao KSMS, Karanth NG. Reverse micellar extraction for downstream processing of proteins/enzymes. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2002; 75:119-83. [PMID: 11787493 DOI: 10.1007/3-540-44604-4_5] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/19/2023]
Abstract
New developments in the area of downstream processing are, hopefully, to fulfill the promises of modern biotechnology. The traditional separation processes such as chromatography or electrophoresis can become prohibitively expensive unless the product is of high value. Hence, there is a need to develop efficient and cost-effective downstream processing methods. Reverse micellar extraction is one such potential and a promising liquid-liquid extraction technique, which has received immense attention for isolation and purification of proteins/enzymes in the recent times. This technique is easy to scale-up and offers continuous operation. This review, besides briefly considering important physico-chemical and biological aspects, highlights the engineering aspects including mass transfer, mathematical modeling, and technology development. It also discusses recent developments in reverse micellar extraction such as affinity based separations, enzymatic reactions in reverse micelles coupled with membrane processes, reverse micellar extraction in hollow fibers, etc. Special emphasis has been given to some recent applications of this technique.
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Affiliation(s)
- S Hari Krishna
- Department of Fermentation Technology & Bioengineering, Central Food Technological Research Institute, Mysore, India.
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27
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Kiran K, Manohar B, Divakar S. A central composite rotatable design analysis of lipase catalyzed synthesis of lauroyl lactic acid at bench-scale level. Enzyme Microb Technol 2001. [DOI: 10.1016/s0141-0229(01)00356-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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28
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Hari Krishna S, Karanth NG. Lipase-catalyzed synthesis of isoamyl butyrate. A kinetic study. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1547:262-7. [PMID: 11410282 DOI: 10.1016/s0167-4838(01)00194-7] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Kinetics of lipase-catalyzed esterification of butyric acid and isoamyl alcohol have been investigated. The reaction rate could be described in terms of the Michaelis-Menten equation with a Ping-Pong Bi-Bi mechanism and competitive inhibition by both the substrates. No evidence of any significant diffusional limitations was detected that could affect the kinetics. The values of the apparent kinetic parameters were computed as: V(max)=11.72 micromol/min/mg; K(M, Acid)=0.00303 M; K(M, Alcohol)=0.00306 M; K(i, Acid)=1.05 M; and K(i, Alcohol)=6.55 M. This study indicates a competitive enzyme inhibition by butyric acid during lipase-catalyzed esterification reaction. Butyric acid, being a short-chain polar acid, concentrates in the microaqueous layer and causes a pH drop in the enzyme microenvironment leading to enzyme inactivation. Butyric acid binds to acyl-enzyme complex unproductively to yield a dead-end intermediate that can no longer give rise to an ester. High concentration of butyric acid gave rise to inactivation of the biocatalyst in addition to dead-end inhibition.
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Affiliation(s)
- S Hari Krishna
- Fermentation Technology and Bioengineering Department, Central Food Technological Research Institute, 570 013, Mysore, India
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Hari Krishna S, Divakar S, Prapulla SG, Karanth NG. Enzymatic synthesis of isoamyl acetate using immobilized lipase from Rhizomucor miehei. J Biotechnol 2001; 87:193-201. [PMID: 11334663 DOI: 10.1016/s0168-1656(00)00432-6] [Citation(s) in RCA: 170] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The effects of important reaction parameters for enhancing isoamyl acetate formation through lipase-catalyzed esterification of isoamyl alcohol were investigated in this study. Increase in substrate (acid) concentration led to decrease in conversions. A critical enzyme concentration of 3 g l(-1) was detected for a substrate concentration of 0.06 M (each of alcohol and acid). Solvents with partition coefficient higher than 1000 (log P>3.0) supported enzyme activity to give high conversions. Acetic acid at higher concentrations could not be esterified easily probably owing to its role in lowering the microaqueous pH of the enzyme. Extraneous water/buffer addition decreased the isoamyl acetate yields slightly ( approximately 10%) at 0.005-0.01% v/v of the reaction mixture and drastically (>40%) at above 0.01% v/v. Buffer saturation of the organic solvent employed improved esterification (upto two-fold), particularly at moderately higher substrate concentrations (>0.18 M). Employing acetic anhydride instead of acetic acid resulted in a two-fold increase in the yields (at 0.25 M substrate). Use of excess nucleophile (alcohol) concentration by increasing the alcohol/acid molar ratio resulted in higher conversions in shorter duration (upto eight-fold even at 1.5 M acetic acid). Yields above 80% were achieved with substrate concentrations as high as 1.5 M and more than 150 g l(-1) isoamyl acetate concentrations were obtained employing a relatively low enzyme concentration of 10 g l(-1). The operational stability of lipase was also observed to be reasonably high enabling ten reuses of the biocatalyst.
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Affiliation(s)
- S Hari Krishna
- Fermentation Technology and Bioengineering Department, Central Food Technological Research Institute, Mysore 570 013, India
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