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Xu Y, Zhang D, Xie F, Li X, Schroyen M, Chen L, Hou C. Changes in water holding capacity of chilled fresh pork in controlled freezing-point storage assisted by different modes of electrostatic field action. Meat Sci 2023; 204:109269. [PMID: 37394351 DOI: 10.1016/j.meatsci.2023.109269] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 06/22/2023] [Accepted: 06/26/2023] [Indexed: 07/04/2023]
Abstract
Electrostatic field-assisted low-temperature preservation is considered a novel technology, which provides an effective means of extending the shelf-life of meat. This study aimed to investigate the effects of different output time modes of a high voltage electrostatic field (HVEF) on the water holding capacity (WHC) of chilled fresh pork during controlled freezing-point storage. Under a direct current HVEF generator, chilled fresh pork samples were treated by the single, interval, or continuous HVEF treatment, with a control check group receiving no HVEF treatment. It was determined that the WHC of the continuous HVEF treatment higher than the control check group. This difference was proven by analyzing the moisture content, storage loss, centrifugal loss, cooking loss, and nuclear magnetic resonance imaging. Furthermore, the mechanism behind HVEF-assisted controlled freezing-point storage reduced the moisture loss was conducted by examining the changes in the hydration characteristics of myofibrillar protein. The study revealed that myofibrillar proteins exhibit high solubility and low surface hydrophobicity under continuous HVEF. Additionally, continuous HVEF has been demonstrated to effectively maintain the higher WHC and lower hardness of myofibrillar protein gel by inhibiting the water molecule migration. The demonstration of these results showcases the effectiveness of electrostatic fields for the future physical preservation of meat.
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Affiliation(s)
- Yuqian Xu
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China; Precision Livestock and Nutrition Unit, Gembloux Agro-Bio Tech, University of Liège, Passage de Déportés 2, Gembloux, Belgium.
| | - Dequan Zhang
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Feifei Xie
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Xin Li
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Martine Schroyen
- Precision Livestock and Nutrition Unit, Gembloux Agro-Bio Tech, University of Liège, Passage de Déportés 2, Gembloux, Belgium
| | - Li Chen
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China
| | - Chengli Hou
- Institute of Food Science and Technology, Chinese Academy of Agricultural Sciences, Key Laboratory of Agro-Products Processing, Ministry of Agriculture and Rural Affairs, Beijing 100193, PR China.
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Kempfer-Robertson EM, Avdic I, Haase MN, Pike TD, Thompson LM. Protonation state control of electric field induced molecular switching mechanisms. Phys Chem Chem Phys 2023; 25:5251-5261. [PMID: 36723228 DOI: 10.1039/d2cp04494c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Scanning tunneling microscopy tip-induced deprotonation has been demonstrated experimentally and can be used as an additional control mechanism in electric-field induced molecular switching. The goal of the current work is to establish whether (de)protonation can be used to inhibit or enhance the electric field controlled thermal and photoisomerization processes. Dihydroxyazobenzene is used as a model system, where protonation/deprotonation of the free hydroxyl moiety changes the azo bond order, and so modifies the rate of electric field induced isomerization. Through the combined action of deprotonation and applied field, it was found that the cis-to-trans thermal isomerization barrier could be completely removed, changing the isomerization half-life from the order of several months. In addition, due to the presence of multiple isomerization mechanisms, electric fields could modify the isomerization kinetics by increasing the number of energetically viable isomerization pathways, rather than reducing the activation barrier of the lowest energy pathway. Excited state calculations indicated that the protonation state and electric field could be used together to control the presence of electronic degeneracies along the rotation pathway between S0/S1, and along all three pathways between S1/S2. This work provides insight into the mechanisms that enable the use of protonation state, light, and electric fields in concert to control molecular switches.
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Affiliation(s)
| | - Irma Avdic
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, USA.
| | - Meagan N Haase
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, USA.
| | - Thomas Dane Pike
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, USA.
| | - Lee M Thompson
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40208, USA.
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Robertson PA, Bishop HM, Orr-Ewing AJ. Tuning the Excited-State Dynamics of Acetophenone Using Metal Ions in Solution. J Phys Chem Lett 2021; 12:5473-5478. [PMID: 34085833 DOI: 10.1021/acs.jpclett.1c01466] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The effects of dissolved metal salts on the excited-state dynamics of acetophenone in solution have been explored by using ultrafast transient absorption spectroscopy at two UV excitation wavelengths. In the absence of metal ions, the S1(nπ*) transition of acetophenone is excited at 320 nm, with intersystem crossing (ISC) occurring with a time constant τISC = 5.95 ± 0.47 ps in acetonitrile solution. Excitation at 280 nm accesses the S2(ππ*) state, which internally converts (<0.2 ps) to S1 before undergoing ISC with τISC = 4.36 ± 0.14 ps. Coordination to Mg2+ ions makes the S2 state accessible to excitation at 320 nm, with the rate of S2 → S1 internal conversion reducing 3-fold but the ISC rate increasing. These changes to the excited-state energies and dynamics of this model photosensitizer indicate that dissolved metal salts could modify the photochemistry of synthetically useful homogeneous photocatalytic systems.
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Affiliation(s)
- Patrick A Robertson
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Hannah M Bishop
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
| | - Andrew J Orr-Ewing
- School of Chemistry, University of Bristol, Cantock's Close, Bristol BS8 1TS, United Kingdom
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Kempfer-Robertson EM, Thompson LM. Effect of Oriented External Electric Fields on the Photo and Thermal Isomerization of Azobenzene. J Phys Chem A 2020; 124:3520-3529. [PMID: 32286821 DOI: 10.1021/acs.jpca.0c00492] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Azobenzene is a prototype molecule with potential applications in molecular switches, solar thermal batteries, sensors, photoresponsive membranes, molecular electronics, data storage, and nonlinear optics. Photo and thermal isomerization pathways exhibit different charge-transfer character and dipole moments, implying that the use of electric fields can be used to modulate the reactivity of azobenzene. This article examines the differential effect of orientated electric fields on the rotation and inversion thermal and photoisomerization pathways of azobenzene to explore the feasibility of using electric fields in the design of azobenzene-based molecular devices. Our findings demonstrate that the application of orientated electric fields modifies the accessibility of the S0/S1 seam of electronic degeneracy, as well as changes the energetically favored relaxation pathway in the branching space to yield different photoproducts. In addition, we observed strong-field dipole-inversion effects that cause a topographical change in the response of the potential energy surface to the applied field and can result in geometric minima that do not exist under field-free conditions. On the S0 surface, transition barriers can be modified on the order of ±10 kcal mol-1, enabling control of thermal isomerization rates.
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Affiliation(s)
| | - Lee M Thompson
- Department of Chemistry, University of Louisville, Louisville, Kentucky 40205, United States
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Mustalahti S, Morozov D, Luk HL, Pallerla RR, Myllyperkiö P, Pettersson M, Pihko PM, Groenhof G. Photoactive Yellow Protein Chromophore Photoisomerizes around a Single Bond if the Double Bond Is Locked. J Phys Chem Lett 2020; 11:2177-2181. [PMID: 32109070 PMCID: PMC7145348 DOI: 10.1021/acs.jpclett.0c00060] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/28/2020] [Indexed: 06/10/2023]
Abstract
Photoactivation in the Photoactive Yellow Protein, a bacterial blue-light photoreceptor, proceeds via photoisomerization of the double C═C bond in the covalently attached chromophore. Quantum chemistry calculations, however, have suggested that in addition to double-bond photoisomerization, the isolated chromophore and many of its analogues can isomerize around a single C-C bond as well. Whereas double-bond photoisomerization has been observed with X-ray crystallography, experimental evidence of single-bond photoisomerization is currently lacking. Therefore, we have synthesized a chromophore analogue, in which the formal double bond is covalently locked in a cyclopentenone ring, and carried out transient absorption spectroscopy experiments in combination with nonadiabatic molecular dynamics simulations to reveal that the locked chromophore isomerizes around the single bond upon photoactivation. Our work thus provides experimental evidence of single-bond photoisomerization in a photoactive yellow protein chromophore analogue and suggests that photoisomerization is not restricted to the double bonds in conjugated systems. This insight may be useful for designing light-driven molecular switches or motors.
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Li Y, Li Y, Su Q, Wang B, Guo N, Liu F. Tuning of energetics and reaction mechanism of water-assisted intramolecular proton transfer of 7-azaindole by external electric field applied in various directions: a TD-DFT study. Theor Chem Acc 2017. [DOI: 10.1007/s00214-017-2052-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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McConnell S, McKenzie RH, Olsen S. Valence-bond non-equilibrium solvation model for a twisting monomethine cyanine. J Chem Phys 2015; 142:084502. [PMID: 25725740 DOI: 10.1063/1.4907758] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
We propose and analyze a two-state valence-bond model of non-equilibrium solvation effects on the excited-state twisting reaction of monomethine cyanines. Suppression of this reaction is thought responsible for environment-dependent fluorescence yield enhancement in these dyes. Fluorescence is quenched because twisting is accompanied via the formation of dark twisted intramolecular charge-transfer (TICT) states. For monomethine cyanines, where the ground state is a superposition of structures with different bond and charge localizations, there are two possible twisting pathways with different charge localizations in the excited state. For parameters corresponding to symmetric monomethines, the model predicts two low-energy twisting channels on the excited-state surface, which leads to a manifold of TICT states. For typical monomethines, twisting on the excited state surface will occur with a small barrier or no barrier. Changes in the solvation configuration can differentially stabilize TICT states in channels corresponding to different bonds, and that the position of a conical intersection between adiabatic states moves in response to solvation to stabilize either one channel or the other. There is a conical intersection seam that grows along the bottom of the excited-state potential with increasing solvent polarity. For monomethine cyanines with modest-sized terminal groups in moderately polar solution, the bottom of the excited-state potential surface is completely spanned by a conical intersection seam.
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Affiliation(s)
- Sean McConnell
- School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia
| | - Ross H McKenzie
- School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia
| | - Seth Olsen
- School of Mathematics and Physics, The University of Queensland, Brisbane 4072, Australia
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Gromov EV. Unveiling the mechanism of photoinduced isomerization of the photoactive yellow protein (PYP) chromophore. J Chem Phys 2014; 141:224308. [DOI: 10.1063/1.4903174] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Affiliation(s)
- Evgeniy V. Gromov
- Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Heidelberg, Germany
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