Protein Oxidation in Foods: Mechanisms, Consequences and Antioxidant Solutions

A special issue of Foods (ISSN 2304-8158). This special issue belongs to the section "Food Quality and Safety".

Deadline for manuscript submissions: closed (31 May 2021) | Viewed by 41495

Special Issue Editors

IPROCAR Research Institute, University of Extremadura, Avda Universidad s/n 10003, Caceres, Spain
Interests: protein oxidation; lipid oxidation; maillard Reaction; muscle foods; phytochemicals; natural antioxidants; food biochemistry; nutrition
Department of Animal and Food Sciences, University of Kentucky, Lexington, KY, 40546, USA
Interests: muscle foods; oxidation; protein conformation; protein fucntionality; antioxidants

Special Issue Information

Dear Colleagues,

The oxidation of food proteins has become a topic of increasing interest given the impact of protein oxidation on protein conformation and functionality as well as food quality. In recent years, numerous papers have contributed to our understanding of the connection between lipid and protein oxidation in food emulsions as well as muscle and dairy foods. Proteins are highly susceptible to the oxidative damage caused by reactive oxygen species as well as reactive carbonyls from lipid oxidation. These changes affect the ability of proteins to form emulsions, gels, and bind water, with these properties being essential in the production of muscle foods. In addition to the routine dinitrophenylhydrazine (DNPH) method, the application of other advanced methodologies such as electron spin resonance (ESR), fluorescence microscopy, chromatographic techniques, and redox proteomics has enabled the further comprehension of protein oxidation fundamentals. It is known that protein oxidation has a straightforward impact on the texture properties of muscle foods. Recent studies have also reported the impact of dietary protein oxidation on the final consumer in terms of loss of nutritional value, dysbiosis, and potential toxic effects on gut health and the physiology of internal organs. These relevant negative effects make it necessary to apply strategies to minimize the occurrence of protein oxidation in food systems. While numerous antioxidant solutions have been tested to inhibit protein oxidation in muscle foods, the molecular interaction between phytochemicals and food proteins as well as their mode of action require further investigation.

This Special Issue of Foods, entitled “Protein Oxidation in Foods: Mechanisms, Consequences and Antioxidant Solutions” invites works (research or reviews) on the current state of knowledge of the subject. This includes a broad field of topics, from molecular fundamentals and mechanisms to applicative studies aiming to understand the negative impact of food protein oxidation and suggesting means of alleviating this issue. These novel papers will surely attract the attention of food scientists worldwide and will inspire future challenges in this field.

Dr. Mario Estévez
Prof. Dr. Youling Xiong
Guest Editors

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Keywords

  • Protein oxidation
  • Carbonyls
  • Antioxidants
  • Protein functionality
  • Food quality
  • Food safety

Published Papers (13 papers)

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Editorial

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5 pages, 218 KiB  
Editorial
Protein Oxidation in Foods: Mechanisms, Consequences, and Antioxidant Solutions
by Mario Estévez and Youling L. Xiong
Foods 2021, 10(10), 2346; https://doi.org/10.3390/foods10102346 - 01 Oct 2021
Cited by 13 | Viewed by 2233
Abstract
Protein oxidation in foods remains a topic of the utmost scientific interest [...] Full article

Research

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13 pages, 2001 KiB  
Article
Physicochemical and Microstructural Characterization of Whey Protein Films Formed with Oxidized Ferulic/Tannic Acids
by Yaosong Wang and Youling L. Xiong
Foods 2021, 10(7), 1599; https://doi.org/10.3390/foods10071599 - 09 Jul 2021
Cited by 16 | Viewed by 5196
Abstract
Protein-based biodegradable packaging films are of environmental significance. The effect of oxidized ferulic acid (OFA)/tannic acid (OTA) on the crosslinking and film-forming properties of whey protein isolate (WPI) was investigated. Both of the oxidized acids induced protein oxidation and promoted WPI crosslinking through [...] Read more.
Protein-based biodegradable packaging films are of environmental significance. The effect of oxidized ferulic acid (OFA)/tannic acid (OTA) on the crosslinking and film-forming properties of whey protein isolate (WPI) was investigated. Both of the oxidized acids induced protein oxidation and promoted WPI crosslinking through the actions of quinone carbonyl and protein sulfhydryl, and amino groups. OTA enhanced the tensile strength (from 4.5 MPa to max 6.7 MPa) and stiffness (from 215 MPa to max 376 MPa) of the WPI film, whereas OFA significantly increased the elongation at break. The water absorption capability and heat resistance of the films were greatly improved by the addition of OTA. Due to the original color of OTA, the incorporation of OTA significantly reduced light transmittance of the WPI film (λ 200–600 nm) as well as the transparency, whereas no significant changes were induced by the OFA treatment. Higher concentrations of OTA reduced the in vitro digestibility of the WPI film, while the addition of OFA had no significant effect. Overall, these two oxidized polyphenols promoted the crosslinking of WPI and modified the film properties, with OTA showing an overall stronger efficacy than OFA due to more functional groups available. Full article
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10 pages, 1446 KiB  
Article
Effect of Addition of Tryptophan on Aggregation of Apo-α-Lactalbumin Induced by UV-Light
by Zichen Zhao, Renjie Li, Mahesha M. Poojary, Søren B. Nielsen and Marianne N. Lund
Foods 2021, 10(7), 1577; https://doi.org/10.3390/foods10071577 - 07 Jul 2021
Cited by 2 | Viewed by 1837
Abstract
UV-B illumination facilitates aggregation of alpha-lactalbumin (α-LA) by intramolecular disulfide bond cleavage followed by intermolecular thiol-disulfide exchange reactions. However, long term exposure to UV-B illumination may induce undesired oxidative modifications of amino acid residues in the protein. The purpose of this study was [...] Read more.
UV-B illumination facilitates aggregation of alpha-lactalbumin (α-LA) by intramolecular disulfide bond cleavage followed by intermolecular thiol-disulfide exchange reactions. However, long term exposure to UV-B illumination may induce undesired oxidative modifications of amino acid residues in the protein. The purpose of this study was to examine the effect of UV-induced aggregation of apo-α-LA (a calcium-depleted form of α-LA) under aerobic and anaerobic conditions and by addition of tryptophan (Trp) as a photosensitizer. The addition of Trp to apo-α-LA illuminated under anaerobic conditions facilitated the highest level of free thiol release and disulfide-mediated aggregation as compared to without addition of Trp under both anaerobic and aerobic conditions. Addition of Trp under aerobic condition resulted in the lowest level of free thiols and disulfide-mediated aggregation and the aerobic conditions caused oxidation of the free Trp with formation of kynurenine and 5-hydroxy-Trp. Minor levels of the Trp oxidation product, 3-hydroxy-kynurenine (2% converted from Trp), was formed in apo-α-LA with added Trp under both aerobic and anaerobic conditions after UV-B treatment. Full article
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15 pages, 2038 KiB  
Article
Inhibition of Protein and Lipid Oxidation in Ready-to-Eat Chicken Patties by a Spondias mombin L. Bagasse Phenolic-Rich Extract
by Deocleciano C. de Santana Neto, Ângela M. T. M. Cordeiro, Bruno R. L. A. Meireles, Íris B. S. Araújo, Mario Estévez, Valquíria C. S. Ferreira and Fábio A. P. Silva
Foods 2021, 10(6), 1338; https://doi.org/10.3390/foods10061338 - 10 Jun 2021
Cited by 13 | Viewed by 2689
Abstract
This study evaluated the impact of yellow mombin (Spondias mombin L.) bagasse extract (YMBE) on the color degradation, protein and lipid oxidation in ready-to-eat chicken patties during 15 days of refrigerated storage. Two formulations of chicken patties were developed: chicken patties control [...] Read more.
This study evaluated the impact of yellow mombin (Spondias mombin L.) bagasse extract (YMBE) on the color degradation, protein and lipid oxidation in ready-to-eat chicken patties during 15 days of refrigerated storage. Two formulations of chicken patties were developed: chicken patties control - PCON (without the antioxidant extract) and chicken patties with yellow mombin extract - PYME (with the antioxidant extract). The extract was effective in maintaining red color and inhibiting myoglobin degradation in the evaluated samples. The generation of lipid oxidation compounds during storage of the treated samples was delayed by 92.37% for peroxide index, 89.89% for conjugated dienes, 74.29% for tiobarbituric acid reactive substances (TBARs) and 92.55% for ρ-anisidine compared to the control samples. Moreover, the addition of YMBE inhibited the formation of carbonyl compounds during cold storage compared to the control samples. Extracts obtained from the yellow mombin bagasse act as a good natural antioxidant for ready-to-eat chicken patties inhibiting protein and lipid oxidative damage during cold storage, being a potential preservative to replace synthetic antioxidants in meat products. Full article
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19 pages, 3499 KiB  
Article
Effects of Sodium Chloride on the Physical and Oxidative Stability of Filled Hydrogel Particles Fabricated with Phase Separation Behavior
by Chuanai Cao, Xin Li, Yongchao Yin, Baohua Kong, Fangda Sun and Qian Liu
Foods 2021, 10(5), 1027; https://doi.org/10.3390/foods10051027 - 09 May 2021
Cited by 2 | Viewed by 2102
Abstract
The objective of this study was to investigate the influence of sodium chloride (NaCl) concentration (0–500 mM) on the physical and oxidative stabilities of filled hydrogel that were stabilized using heat-denatured whey protein concentrate and high methoxy pectin. Our results showed that with [...] Read more.
The objective of this study was to investigate the influence of sodium chloride (NaCl) concentration (0–500 mM) on the physical and oxidative stabilities of filled hydrogel that were stabilized using heat-denatured whey protein concentrate and high methoxy pectin. Our results showed that with an increase in NaCl concentration, the particle sizes, zeta-potentials, and interfacial layer thickness of filled hydrogels significantly increased and the lightness and whiteness gradually decreased (p < 0.05). Moreover, rheological characterization revealed that the apparent viscosity and viscoelastic behavior gradually decreased at higher NaCl concentration, which was mainly ascribed to the influence of NaCl on the electrostatic repulsion between droplets, thereby adversely impacting the physical stability of filled hydrogels. Furthermore, the result of cryo-scanning electron microscopy also verified the abovementioned results. Notably, higher NaCl concentration significantly promoted the oxidation of lipids and proteins (p < 0.05), thereby decreasing the oxidative stabilities of filled hydrogels. Our results indicated that filled hydrogels prepared under different ionic strength conditions can provide the theoretical basis for their future application in emulsion-based foods. Full article
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8 pages, 1753 KiB  
Communication
Investigation by Synchrotron Radiation Circular Dichroism of the Secondary Structure Evolution of Pepsin under Oxidative Environment
by Laetitia Théron, Aline Bonifacie, Jérémy Delabre, Thierry Sayd, Laurent Aubry, Philippe Gatellier, Christine Ravel, Christophe Chambon, Thierry Astruc, Jacques Rouel, Véronique Santé-Lhoutellier, Matthieu Réfrégiers and Frank Wien
Foods 2021, 10(5), 998; https://doi.org/10.3390/foods10050998 - 02 May 2021
Cited by 3 | Viewed by 1814
Abstract
Food processing affects the structure and chemical state of proteins. In particular, protein oxidation occurs and may impair protein properties. These chemical reactions initiated during processing can develop during digestion. Indeed, the physicochemical conditions of the stomach (oxygen pressure, low pH) favor oxidation. [...] Read more.
Food processing affects the structure and chemical state of proteins. In particular, protein oxidation occurs and may impair protein properties. These chemical reactions initiated during processing can develop during digestion. Indeed, the physicochemical conditions of the stomach (oxygen pressure, low pH) favor oxidation. In that respect, digestive proteases may be affected as well. Yet, very little is known about the link between endogenous oxidation of digestive enzymes, their potential denaturation, and, therefore, food protein digestibility. Thus, the objective of this study is to understand how oxidative chemical processes will impact the pepsin secondary structure and its hydrolytic activity. The folding and unfolding kinetics of pepsin under oxidative conditions was determined using Synchrotron Radiation Circular Dichroism. SRCD gave us the possibility to monitor the rapid kinetics of protein folding and unfolding in real-time, giving highly resolved spectral data. The proteolytic activity of control and oxidized pepsin was investigated by MALDI-TOF mass spectrometry on a meat protein model, the creatine kinase. MALDI-TOF MS allowed a rapid evaluation of the proteolytic activity through peptide fingerprint. This study opens up new perspectives by shifting the digestion paradigm taking into account the gastric digestive enzyme and its substrate. Full article
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15 pages, 2245 KiB  
Article
New Insights into the Chemical Reactivity of Dry-Cured Fermented Sausages: Focus on Nitrosation, Nitrosylation and Oxidation
by Aline Bonifacie, Philippe Gatellier, Aurélie Promeyrat, Gilles Nassy, Laurent Picgirard, Valérie Scislowski, Véronique Santé-Lhoutellier and Laetitia Théron
Foods 2021, 10(4), 852; https://doi.org/10.3390/foods10040852 - 14 Apr 2021
Cited by 14 | Viewed by 2203
Abstract
Nitrite and nitrate are added to cured meat for their bacteriological, technological and sensorial properties. However, they are suspected to be involved in the formation of nitroso compounds (NOCs), such as potentially mutagenic nitrosamines, nitrosylheme and nitrosothiols. Controlling the sanitary and sensorial qualities [...] Read more.
Nitrite and nitrate are added to cured meat for their bacteriological, technological and sensorial properties. However, they are suspected to be involved in the formation of nitroso compounds (NOCs), such as potentially mutagenic nitrosamines, nitrosylheme and nitrosothiols. Controlling the sanitary and sensorial qualities of cured meat products by reducing these additives requires elucidating the mechanisms involved in the formation of NOCs. To this end, we studied the dose-response relationship of added sodium nitrite and/or sodium nitrate (0/0, 80/80, 0/200, and 120/120 ppm) on the formation of NOCs in dry cured fermented sausages. The results showed a basal heme iron nitrosylation in the absence of NaNO2/NaNO3 due to starter cultures. This reaction was promoted by the addition of NaNO2/NaNO3 in the other conditions. Reducing the dose to 80/80 ppm still limits lipid oxidation without the formation of non-volatile nitrosamines. Conversely, the addition of NO2/NO3 slightly increases protein oxidation through higher carbonyl content. The use of 80/80 ppm could be a means of reducing these additives in dry-cured fermented meat products. Full article
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18 pages, 5028 KiB  
Article
Ultrasonic Freezing Reduces Protein Oxidation and Myofibrillar Gel Quality Loss of Common Carp (Cyprinus carpio) during Long-Time Frozen Storage
by Qinxiu Sun, Baohua Kong, Shucheng Liu, Ouyang Zheng and Chao Zhang
Foods 2021, 10(3), 629; https://doi.org/10.3390/foods10030629 - 16 Mar 2021
Cited by 28 | Viewed by 2859
Abstract
Ultrasonic freezing (UF) is an effective method to increase the freezing speed and improve the quality of frozen food. The effect of UF on myofibrillar protein oxidation and gel properties of common carp (Cyprinus carpio) during frozen storage were investigated with [...] Read more.
Ultrasonic freezing (UF) is an effective method to increase the freezing speed and improve the quality of frozen food. The effect of UF on myofibrillar protein oxidation and gel properties of common carp (Cyprinus carpio) during frozen storage were investigated with air freezing (AF) and immersion freezing (IF) as controls. The results showed that the carbonyl and dityrosine content of UF samples were lower and the free amine content was higher than those of AF and IF samples during frozen storage indicating that UF inhibited protein oxidation caused by frozen storage. The particle size of UF myofibrillar protein was the smallest among all the groups indicating that UF inhibited the protein aggregation. The UF sample had higher G’, G” value, gel strength and gel water holding capacity than AF and IF groups showing that UF reduced the loss of protein gel properties. The gel microstructure showed that UF protein gel was characterized by smaller and finer pores than other samples, which further proves that UF inhibited loss of gel properties during frozen storage. The UF sample had shorter T2 transition time than other samples demonstrating that UF decreased the mobility of water. In general, UF is an effective method to reduce protein oxidation and gel properties loss caused by frozen storage. Full article
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14 pages, 1904 KiB  
Article
Comparative Study of Oxidative Structural Modifications of Unadsorbed and Adsorbed Proteins in Whey Protein Isolate-Stabilized Oil-in-Water Emulsions under the Stress of Primary and Secondary Lipid Oxidation Products
by Jiaxin Chen, Jinhai Zhao, Baohua Kong, Qian Chen, Qian Liu and Chengguo Liu
Foods 2021, 10(3), 593; https://doi.org/10.3390/foods10030593 - 11 Mar 2021
Cited by 16 | Viewed by 1911
Abstract
The impact of typical primary or secondary lipid oxidation (LPO) products, selected as linoleic acid 13-hydroperoxide (13-HPODE) and malondialdehyde (MDA), on the structural modification of unadsorbed or adsorbed proteins in whey protein isolate (WPI)-stabilized oil-in-water (O/W) emulsions during storage up to 48 h [...] Read more.
The impact of typical primary or secondary lipid oxidation (LPO) products, selected as linoleic acid 13-hydroperoxide (13-HPODE) and malondialdehyde (MDA), on the structural modification of unadsorbed or adsorbed proteins in whey protein isolate (WPI)-stabilized oil-in-water (O/W) emulsions during storage up to 48 h at 37 °C in the dark was investigated. The results showed that either 13-HPODE and MDA could lead to structural modifications of unadsorbed or adsorbed proteins with a concentration-dependent manner and time relationship, respectively. Moreover, higher levels of MDA rendered a higher degree of oxidative modifications of WPI than 13-HPODE, indicated by the higher protein carbonyl contents and N’-formyl-L-kynurenine (NFK) and lower fluorescence intensity. Additionally, adsorbed proteins were more easily oxidized by LPO products than unadsorbed proteins. Overall, our results indicated that the formation of secondary LPO products and the protein position were crucial factors to increase the degree of oxidative modifications of WPI in O/W emulsion systems. Full article
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15 pages, 3865 KiB  
Article
Effect of High Voltage Cold Plasma on Oxidation, Physiochemical, and Gelling Properties of Myofibrillar Protein Isolate from Asian Sea Bass (Lates calcarifer)
by Oladipupo Odunayo Olatunde, Avtar Singh, Khursheed Ahmad Shiekh, Pornpot Nuthong and Soottawat Benjakul
Foods 2021, 10(2), 326; https://doi.org/10.3390/foods10020326 - 04 Feb 2021
Cited by 25 | Viewed by 3246
Abstract
The effects of in-bag dielectric barrier discharge high voltage cold plasma (IB-DBD-HVCP) on myofibrillar protein isolate (MPI) from Asian sea bass (ASB) and its impact on the physiochemical and gelling properties of MPI gels were elucidated. A mixture of argon (90%) and oxygen [...] Read more.
The effects of in-bag dielectric barrier discharge high voltage cold plasma (IB-DBD-HVCP) on myofibrillar protein isolate (MPI) from Asian sea bass (ASB) and its impact on the physiochemical and gelling properties of MPI gels were elucidated. A mixture of argon (90%) and oxygen (10%) was used for generating IB-DBD-HVCP. MPI was subjected to IB-DBD-HVCP for varying times (5–15 min). Total carbonyl content was increased, while total sulfhydryl content was decreased in MPI, especially with augmenting treatment time (TT) (p < 0.05). Surface hydrophobicity initially increased when IB-DBD-HVCP TT of 5 min (DBD-HVCP5) was implemented, followed by subsequent decrease with increasing TT. Based on gel electrophoresis, lower actin and myosin heavy chain (MHC) band intensities were found for MPI subjected to IB-DBD-HVCP, particularly when a TT longer than 10 min was used, compared to those of the control. Gel made from DBD-HVCP5 had higher breaking force, deformation, and highest G′ value compared to others. A more ordered and fibrous network was found in DBD-HVCP5 treated gel. Therefore, IB-DBD-HVCP treatment, particularly for 5 min, enhanced cross-linking of proteins in ASB myofibrillar proteins, which resulted in the improved gel elasticity and strength. Full article
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14 pages, 4894 KiB  
Article
Effect of Oxidation on Quality of Chiba Tofu Produced by Soy Isolate Protein When Subjected to Storage
by Yue Xu, Zhongjiang Wang, Baokun Qi, Anqi Ran, Zengwang Guo and Lianzhou Jiang
Foods 2020, 9(12), 1877; https://doi.org/10.3390/foods9121877 - 17 Dec 2020
Cited by 9 | Viewed by 2162
Abstract
Chiba tofu is a new type of vegetarian food prepared with soy protein isolate (SPI). According to factory feedback, the SPI stored in the factory storeroom in summer undergoes reactive oxidation, which changes the structure of SPI and further affects the quality of [...] Read more.
Chiba tofu is a new type of vegetarian food prepared with soy protein isolate (SPI). According to factory feedback, the SPI stored in the factory storeroom in summer undergoes reactive oxidation, which changes the structure of SPI and further affects the quality of Chiba tofu. Consequently, the main objective of this study was to prepare Chiba tofu with SPI with different storage periods and evaluate the effect of different degrees of oxidation on structural characteristics of SPI and rheology, texture, microstructure and sensory properties of Chiba tofu. The carbonyl content and turbidity of SPI significantly increased, and the contents of free sulfhydryl (SH) and disulfide bond (S-S) simultaneously decreased with storage time. The oxidation changes the SPI conformation, leading to a transition of α-helix and β-turn to β-sheet and random coil during the storage periods. In the SDS–PAGE analysis, oxidation promoted the SPI molecules crosslinked and aggregated, which affected the quality of Chiba tofu. In short storage periods (0–12 days), SPI was relatively moderately oxidized when the carbonyl content was between 4.14 and 6.87 mmol/g. The storage and loss modulus of Chiba tofu both increased, the network was compact, and the hardness and springiness of Chiba tofu showed an increasing trend. Moreover, in longer storage periods (12–30 days), the SPI was relatively severely oxidized when the carbonyl content was between 7.24 and 9.14 mmol/g, which had an adverse effect on Chiba tofu rheological and texture properties, microstructure, and sensory properties. In sensory evaluation, Chiba tofu stored 12 days had the highest overall quality score than that stored on other days. This study is expected to provide an argument for the better industrial production of Chiba tofu. Full article
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18 pages, 981 KiB  
Article
Effectiveness of Sprayed Bioactive Fruit Extracts in Counteracting Protein Oxidation in Lamb Cutlets Subjected to a High-Oxygen MAP
by D. Morcuende, C. Vallejo-Torres, S. Ventanas, S. L. Martínez, S. C. Ruiz and M. Estévez
Foods 2020, 9(11), 1715; https://doi.org/10.3390/foods9111715 - 22 Nov 2020
Cited by 10 | Viewed by 2451
Abstract
High-oxygen packaging atmosphere (High-Ox-MAP) promotes meat protein oxidation and leads to texture deterioration. This study was conceived to assess the extent to which sprayed fruit extracts could inhibit the oxidative damage to proteins in lamb cutlets subjected to High-Ox-MAP (10 days/4 °C) and [...] Read more.
High-oxygen packaging atmosphere (High-Ox-MAP) promotes meat protein oxidation and leads to texture deterioration. This study was conceived to assess the extent to which sprayed fruit extracts could inhibit the oxidative damage to proteins in lamb cutlets subjected to High-Ox-MAP (10 days/4 °C) and subsequent roasting (10 min/180 °C). Extracts from oaknut (Quercus ilex subsp. ballota; QI), rose hips (Rosa canina L.; RC), common hawthorn (Crataegus monogyna Jacq.; CM) and strawberry tree (Arbutus unedo L.; AU) were characterized for bioactive compounds (phenolic subclasses, tocopherols and ascorbic acid) and in vitro bioactivities. While the four fruits showed relevant antioxidant potential, CM had the highest phenolics and tocopherol content and that was reflected in efficient antiradical activity. The in vitro activity of this fruit to inhibit meat protein oxidation was, however, lower than that displayed by the other fruits. Taking the results altogether, CM was also found to be most efficient in protecting lamb cutlets from lipid oxidation. All fruits were able to inhibit thiols oxidation except RC, which seemed to reduce protein thiols. Among fruits, QI was the most efficient in protecting lamb cutlets against protein carbonylation as a plausible involvement of ellagitannins. The inhibition of protein oxidation by QI was reflected in significantly lower instrumental hardness in cooked lamb cutlets. Spraying lamb cutlets with extracts from QI, RC and CM improved consumers’ purchase intention after chilled storage. This antioxidant strategy seems to be a feasible and efficient solution to the pro-oxidative effects caused by High-Ox-MAP in red meat. Full article
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Review

Jump to: Editorial, Research

22 pages, 1831 KiB  
Review
Animal and Plant Protein Oxidation: Chemical and Functional Property Significance
by Youling L. Xiong and Anqi Guo
Foods 2021, 10(1), 40; https://doi.org/10.3390/foods10010040 - 25 Dec 2020
Cited by 83 | Viewed by 7831
Abstract
Protein oxidation, a phenomenon that was not well recognized previously but now better understood, is a complex chemical process occurring ubiquitously in food systems and can be induced by processing treatments as well. While early research concentrated on muscle protein oxidation, later investigations [...] Read more.
Protein oxidation, a phenomenon that was not well recognized previously but now better understood, is a complex chemical process occurring ubiquitously in food systems and can be induced by processing treatments as well. While early research concentrated on muscle protein oxidation, later investigations included plant, milk, and egg proteins. The process of protein oxidation involves both radicals and nonradicals, and amino acid side chain groups are usually the site of initial oxidant attack which generates protein carbonyls, disulfide, dityrosine, and protein radicals. The ensuing alteration of protein conformational structures and formation of protein polymers and aggregates can result in significant changes in solubility and functionality, such as gelation, emulsification, foaming, and water-holding. Oxidant dose-dependent effects have been widely reported, i.e., mild-to-moderate oxidation may enhance the functionality while strong oxidation leads to insolubilization and functionality losses. Therefore, controlling the extent of protein oxidation in both animal and plant protein foods through oxidative and antioxidative strategies has been of wide interest in model system as well in in situ studies. This review presents a historical perspective of food protein oxidation research and provides an inclusive discussion of the impact of chemical and enzymatic oxidation on functional properties of meat, legume, cereal, dairy, and egg proteins based on the literature reports published in recent decades. Full article
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