- Email: [email protected]
Cold plasma: background, applications and current trends
Accepted Manuscript Title: Cold plasma: background, applications and current trends Author: S.K. Pankaj Kevin M. Keener PII: DOI: Reference:
S2214-7993(16)30127-8 http://dx.doi.org/doi:10.1016/j.cofs.2017.07.008 COFS 257
To appear in: Received date: Revised date: Accepted date:
19-4-2017 11-7-2017 31-7-2017
Please cite this article as: Pankaj, S.K., Keener, K.M.,Cold plasma: background, applications and current trends, COFS (2017), http://dx.doi.org/10.1016/j.cofs.2017.07.008 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Cold plasma: background, applications and current trends S. K. Pankaja, Kevin M. Keenera* Center for Crops Utilization Research, Iowa State University, Ames, IA, USA, 50011
an
us
cr
ip t
a
M
*Corresponding Author: Kevin M. Keener
te
Ac ce p
1-515-294-0160
d
[email protected]
Page 1 of 11
Abstract
ip t
Cold plasma technology offers several potential applications in the food and biomedical industries. This work aims at highlighting the potential applications of cold plasma in food
cr
industry highlighting the current research and trends in this area. The main applications of cold plasma for food industry could be grouped as food decontamination, food quality improvement,
us
toxin degradation and surface modifications of packaging materials. Cold plasma has proven to
an
be effective for inactivation of various pathogens and spoilage organisms without adversely affecting the food quality. It has also shown the potential for significant degradation of
M
mycotoxins and pesticides present in the agricultural produce. Current plasma research is driven to analyze its effectiveness against various pathogens in different food products with a keen
d
emphasis to gain insights on the inactivation mechanisms at a molecular level. Although, cold
te
plasma technology has shown promising results, it require further studies to understand the
Ac ce p
reactive gas chemistry, toxicological, ecological and economic impacts of this technology. Keywords: Cold plasma; food decontamination; toxin degradation; food packaging
Page 2 of 11
Introduction
ip t
Cold plasma is a novel non-thermal technology, which has shown significant potential for applications in food industries. Earlier, cold plasma was widely used mainly in the polymer and
cr
electronic industry for surface modification and functionalization of different polymers.
us
However, in recent years, the applications of cold plasma has rapidly expanded into treatment of biomedical devices and biological materials, including foods [1].
an
The term ‘plasma’ refers to a quasi-neutral ionized gas, primarily composed of photons, ions and free electrons as well as atoms in their fundamental or excited states with a net neutral charge
M
[2]. Plasma is generally categorized as ‘thermal’ when electrons and other gas species are in thermodynamic equilibrium and ‘non-thermal’ when they exist in non-equilibrium. Earlier, cold
d
plasma were generated under low-pressure conditions limiting its applications. However, recent
te
advances in plasma engineering have allowed cold plasma generation at atmospheric pressure
Ac ce p
leading to increased research on cold plasma at various interfaces of life sciences. A summary of major applications of cold plasma technology is shown in Figure 1. Figure 1: Summary of major applications of cold plasma technology
There are various types of cold plasma generation systems used for different applications in the industry. They could range from corona discharges, microwave plasma, radio frequency plasma, inductively coupled plasma, capacity coupled plasma, electron cyclotron resonance plasma and dielectric barrier discharge plasma. Among these, dielectric barrier discharge and jet plasma are the most used for food research owing to their simple, versatile and adaptive designs and working.
Page 3 of 11
Plasma can be generated in any neutral gas by providing sufficient energy for its ionization making plasma chemistry much more complex. For example, air plasma consists of over 75 unique species and more than 500 chemical reactions happening at nano, micro, milli and
ip t
seconds time scales [3]. There is a continuing research in the field of plasma chemistry for
identification of reactive species generated in the plasma and their interaction with the biological
cr
and chemical components of food products. This requires research efforts to understand the
us
mechanisms for microbial inactivation, toxin degradation, or other desirable effects and
an
subsequently leverage such information for food product/process improvement. Applications of cold plasma
M
Specifically for the food industry, current cold plasma research are focused on its applications
te
the following sections.
d
for food decontamination, toxin degradation and packaging modifications which are discussed in
Cold plasma for food decontamination
Ac ce p
Cold plasma has proven an effective non-thermal processing technology for inactivation of various pathogenic and spoilage microorganisms found in the food products. There are various reviews available in literature on application of cold plasma providing a snapshot of progress of cold plasma technology in food processing [4-8]. Although, most of the current studies are still focused on exploring and optimizing the plasma decontamination process conditions for different food products targeting various microorganisms, there has been a significant interest for understanding the plasma inactivation mechanisms for different microorganisms. It was previously reported that reactive oxygen species play the most crucial role in microbial inactivation leading to strong oxidative stress conditions, causing cell damage by lipid
Page 4 of 11
peroxidation, enzyme inactivation and DNA cleavage [9]. Recently, L Han, et al. [10] have reported different inactivation mechanisms for Gram positive and Gram negative bacteria by cold plasma. They showed that cold plasma inactivation of Gram positive bacteria
ip t
(Staphylococcus aureus) was mainly due to intracellular damage and little envelope damage
whereas Gram negative bacteria (Escherichia coli) was inactivated mainly by cell leakage and
cr
low-level DNA damage. A succint review by P Bourke, et al. [11] have summarized the
us
interactions of plasma gas species with a range of microbiological targets along with the advances in the mechanistic insights. These studies clearly indicates the selective and differential
M
mechanistic studies for better understanding.
an
interactions of reactive gas species in the plasma systems emphasizing the need for future
Apart from microbial inactivation, effects of cold plasma on the food quality has been another
d
important aspect drawing attention of food researchers. Cold plasma inactivation of food
te
enzymes have received significant attention in this regard. A review by NN Misra, et al. [1]
Ac ce p
reported that plasma gas species causes loss of secondary enzyme structure due to breakdown of specific bonds or chemical modifications of the side chains and were dependent on power input, degree of exposure, mass transfer between the plasma-liquid phases, structural complexity and stability of the enzymes in their local environment. Further research are recommended for identification of plasma generated reactive species and their interaction with potential microorganisms and food components at molecular level for further mechanistic understanding. Cold plasma for toxin degradation
Page 5 of 11
Natural and synthetic toxins are ubiquitously present in our ecosystem. Toxic compounds such as trypsin inhibitors, saponins, goitrogens, lectins might be inherently present in various food products. Other toxins like pesticides, endocrine disruptors, mycotoxins etc. are also present in
ip t
our food and water system raising concern for consumer health and safety. Currently, there are very limited non-thermal technologies available for control and degradation of toxic compounds
cr
present in food products. Cold plasma has shown promising potential for degradation of various
us
food toxins gaining increased interest from food researchers in past few years. Most of the current research in food products are focused on cold plasma degradation of mycotoxins and
an
pesticides.
M
Mycotoxins are toxic secondary metabolites produced by filamentous fungi contaminating various food products posing serious health risks problems. Many of the mycotoxins have been
d
classified as carcinogenic, mutagenic and genotoxic. The resistance for degradation of
te
mycotoxins by thermal processing and inability to completely inactivate them by conventional
Ac ce p
processing has led to active research for alternative processing technologies. Cold plasma has shown significant degradation of mycotoxins in various food products [12,13]. Researchers are now focusing on optimizing the process parameters to increase the degradation efficiency along with insights into the degradation mechanism [14-16]. Although, cold plasma has been presented as a viable alternative, further studies are required to understands the reaction mechanism in presence of different reactive species along with the toxicity study of degradation products. The use of pesticides is a common agricultural practice which has significantly decreased the crop losses by insects and in turn increasing the yield at a global scale. However, pesticides are also toxic for humans and thus have to be stringently regulated below the residual toxicity limit in all the food products. The use of cold plasma has proven efficient in degradation of many
Page 6 of 11
pesticides in various food products [17-20]. The effectiveness of cold plasma for pesticide degradation has been attributed to the generation of different reactive gas species like ions (H3O+, O+, O−, OH−, N2+), molecular species (O3, H2O2), and reactive radicals (O•, OH•, NO•).
ip t
Future studies are recommended to analyze the degradation efficiency in different classes of
cr
pesticides, degradation mechanism and toxicity of degradation intermediates and products.
us
Cold plasma for food packaging
Cold plasma is being used in the packaging industry for many decades. It has been extensively
an
used for packaging material sterilization, surface etching, surface functionalization, surface activation and surface deposition. Many reviews on the applications of cold plasma for food
M
packaging have been published previously [2,21]. Along with its use for conventional polymers, recently it has been used for surface modification of bio-based films and coatings [22-24]. Some
d
recent studies have also shown the potential of cold plasma to be used for active [25-27] and
te
intelligent packaging materials [28]. Current trends in this area continues with plasma treatment
Ac ce p
of different packaging materials to improve their packaging properties. Conclusions
Cold plasma is an emerging non-thermal technology which has shown potential applications at different interfaces of life sciences. In food industry, its application are mostly focused on food decontamination, improving food quality, degradation of toxins and surface modification of packaging materials. Cold plasma has shown some unique advantages over traditional technologies to offer solutions for current problems in the food industry. However, cold plasma technology is still in its nascent stage and requires further work in system designing, scalability
Page 7 of 11
studies, eco-toxicity studies and mechanistic insights before it could be fully utilized at a commercial scale.
ip t
Reference Papers of particular interest, published within the period of review, have been highlighted as:
cr
• of special interest
us
•• of outstanding interest
M
an
••1. Misra NN, Pankaj SK, Segat A, Ishikawa K: Cold plasma interactions with enzymes in foods and model systems. Trends in Food Science & Technology 2016, 55:39-47. This article is an excellent review of enzyme inzctivation in food and model systems by cold plasma. This paper includes the basics of cold plasma, summarizing studies for important enzymes inactivations along with an insight into the inactivation mechanism.
Ac ce p
te
d
2. Pankaj SK, Bueno-Ferrer C, Misra NN, Milosavljević V, O'Donnell CP, Bourke P, Keener KM, Cullen PJ: Applications of cold plasma technology in food packaging. Trends in Food Science & Technology 2014, 35:5-17. 3. Gordillo-Vázquez FJ: Air plasma kinetics under the influence of sprites. Journal of Physics D: Applied Physics 2008, 41:234016. 4. Misra N, Jo C: Applications of cold plasma technology for microbiological safety in meat industry. Trends in Food Science & Technology 2017. 5. Misra NN, Tiwari BK, Raghavarao KSMS, Cullen PJ: Nonthermal Plasma Inactivation of FoodBorne Pathogens. Food Engineering Reviews 2011, 3:159-170. 6. Niemira BA: Cold plasma decontamination of foods. Annual review of food science and technology 2012, 3:125-142. 7. Surowsky B, Schlüter O, Knorr D: Interactions of non-thermal atmospheric pressure plasma with solid and liquid food systems: a review. Food Engineering Reviews 2015, 7:82-108. 8. Thirumdas R, Sarangapani C, Annapure US: Cold plasma: a novel non-thermal technology for food processing. Food biophysics 2015, 10:1-11. 9. Han L, Patil S, Keener KM, Cullen PJ, Bourke P: Bacterial inactivation by high-voltage atmospheric cold plasma: influence of process parameters and effects on cell leakage and DNA. Journal of Applied Microbiology 2014, 116:784-794. •10. Han L, Patil S, Boehm D, Milosavljević V, Cullen PJ, Bourke P: Mechanisms of inactivation by high-voltage atmospheric cold plasma differ for Escherichia coli and Staphylococcus aureus. Applied and environmental microbiology 2016, 82:450-458. This study shows the differential mode of inactivation for Gram positive and Gram negative bacteria after cold atmospheric plasma treatment. This study also suggests that plasma gas species reactions are primarily dependent on the microbial cell structure and chemical composition. ••11. Bourke P, Zuizina D, Han L, Cullen P, Gilmore BF: Microbiological Interactions with Cold Plasma. Journal of Applied Microbiology 2017.
Page 8 of 11
This is a succint review of previous studies of microbial decontaminations by cold plasma in food and biomedical sciences. This work also critically analyzed the microbiological interactions of plasma reactive species at the cellular level.
us
cr
ip t
12. ten Bosch L, Pfohl K, Avramidis G, Wieneke S, Viöl W, Karlovsky P: Plasma-Based Degradation of Mycotoxins Produced by Fusarium, Aspergillus and Alternaria Species. Toxins 2017, 9:97. 13. Siciliano I, Spadaro D, Prelle A, Vallauri D, Cavallero MC, Garibaldi A, Gullino ML: Use of cold atmospheric plasma to detoxify hazelnuts from aflatoxins. Toxins 2016, 8:125. •14. Sakudo A, Toyokawa Y, Misawa T, Imanishi Y: Degradation and detoxification of aflatoxin B1 using nitrogen gas plasma generated by a static induction thyristor as a pulsed power supply. Food Control 2017, 73, Part B:619-626. This article illustrates the degradation efficiency of aflatoxin by nitogen gas plasma. It also analyzed the effects of plasma process variables on the degradation rate. They also showed that nitrogen gas plasma treatment not only cause degradation of aflatoxin but also reduces the physiological activity of the samples.
Ac ce p
te
d
M
an
15. Shi H, Ileleji K, Stroshine RL, Keener K, Jensen JL: Reduction of Aflatoxin in Corn by High Voltage Atmospheric Cold Plasma. Food and Bioprocess Technology 2017:1-11. 16. Wang S-Q, Huang G-Q, Li Y-P, Xiao J-X, Zhang Y, Jiang W-L: Degradation of aflatoxin B1 by low-temperature radio frequency plasma and degradation product elucidation. European Food Research and Technology 2015, 241:103-113. 17. Bai Y, Chen J, Mu H, Zhang C, Li B: Reduction of Dichlorvos and Omethoate Residues by O2 Plasma Treatment. Journal of Agricultural and Food Chemistry 2009, 57:6238-6245. 18. Misra N, Pankaj S, Walsh T, O’Regan F, Bourke P, Cullen P: In-package nonthermal plasma degradation of pesticides on fresh produce. Journal of hazardous materials 2014, 271:33-40. 19. Sarangapani C, O'Toole G, Cullen P, Bourke P: Atmospheric cold plasma dissipation efficiency of agrochemicals on blueberries. Innovative Food Science & Emerging Technologies 2017. 20. Misra N: The contribution of non-thermal and advanced oxidation technologies towards dissipation of pesticide residues. Trends in Food Science & Technology 2015, 45:229-244. 21. Pankaj S, Thomas S: Cold Plasma Applications in Food Packaging. Cold Plasma in Food and Agriculture: Fundamentals and Applications 2016:293. 22. Pankaj SK, Bueno-Ferrer C, Misra N, O'Neill L, Tiwari B, Bourke P, Cullen P: Dielectric barrier discharge atmospheric air plasma treatment of high amylose corn starch films. LWT-Food Science and Technology 2015, 63:1076-1082. 23. Pankaj SK, Bueno-Ferrer C, Misra NN, Bourke P, Cullen PJ: Zein film: Effects of dielectric barrier discharge atmospheric cold plasma. Journal of Applied Polymer Science 2014, 131. 24. Oh YA, Roh SH, Min SC: Cold plasma treatments for improvement of the applicability of defatted soybean meal-based edible film in food packaging. Food Hydrocolloids 2016, 58:150-159. 25. Pankaj S, Bueno-Ferrer C, Misra N, O’Neill L, Bourke P, Cullen P: Effects of Cold Plasma on Surface, Thermal and Antimicrobial Release Properties of Chitosan Film. Journal of Renewable Materials 2016. 26. Clarke D, Tyuftin AA, Cruz-Romero MC, Bolton D, Fanning S, Pankaj SK, Bueno-Ferrer C, Cullen PJ, Kerry JP: Surface attachment of active antimicrobial coatings onto conventional plasticbased laminates and performance assessment of these materials on the storage life of vacuum packaged beef sub-primals. Food Microbiology 2017, 62:196-201. 27. Pankaj S, Bueno-Ferrer C, Misra N, O’Neill L, Jiménez A, Bourke P, Cullen P: Surface, Thermal and Antimicrobial Release Properties of Plasma-Treated Zein Films. Journal of Renewable Materials 2014:1-8.
Page 9 of 11
Ac ce p
te
d
M
an
us
cr
ip t
28. Pankaj S, Kelly CA, Bueno-Ferrer C, Kerry JP, Papkovsky DB, Bourke P, Cullen P: Application of phosphorescent oxygen sensors in in-package dielectric barrier discharge plasma environment. Innovative Food Science & Emerging Technologies 2016, 33:234-239.
Highlights •
Cold plasma shows promising applications for food industries.
•
It can be used for microbial inactivation and toxin degradation in food products.
•
Cold plasma can also be used for food packaging materials modifications.
Page 10 of 11
Page 11 of 11
ed
pt
ce
Ac M
an
us
cr
i
S2214-7993(16)30127-8 http://dx.doi.org/doi:10.1016/j.cofs.2017.07.008 COFS 257
To appear in: Received date: Revised date: Accepted date:
19-4-2017 11-7-2017 31-7-2017
Please cite this article as: Pankaj, S.K., Keener, K.M.,Cold plasma: background, applications and current trends, COFS (2017), http://dx.doi.org/10.1016/j.cofs.2017.07.008 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Cold plasma: background, applications and current trends S. K. Pankaja, Kevin M. Keenera* Center for Crops Utilization Research, Iowa State University, Ames, IA, USA, 50011
an
us
cr
ip t
a
M
*Corresponding Author: Kevin M. Keener
te
Ac ce p
1-515-294-0160
d
[email protected]
Page 1 of 11
Abstract
ip t
Cold plasma technology offers several potential applications in the food and biomedical industries. This work aims at highlighting the potential applications of cold plasma in food
cr
industry highlighting the current research and trends in this area. The main applications of cold plasma for food industry could be grouped as food decontamination, food quality improvement,
us
toxin degradation and surface modifications of packaging materials. Cold plasma has proven to
an
be effective for inactivation of various pathogens and spoilage organisms without adversely affecting the food quality. It has also shown the potential for significant degradation of
M
mycotoxins and pesticides present in the agricultural produce. Current plasma research is driven to analyze its effectiveness against various pathogens in different food products with a keen
d
emphasis to gain insights on the inactivation mechanisms at a molecular level. Although, cold
te
plasma technology has shown promising results, it require further studies to understand the
Ac ce p
reactive gas chemistry, toxicological, ecological and economic impacts of this technology. Keywords: Cold plasma; food decontamination; toxin degradation; food packaging
Page 2 of 11
Introduction
ip t
Cold plasma is a novel non-thermal technology, which has shown significant potential for applications in food industries. Earlier, cold plasma was widely used mainly in the polymer and
cr
electronic industry for surface modification and functionalization of different polymers.
us
However, in recent years, the applications of cold plasma has rapidly expanded into treatment of biomedical devices and biological materials, including foods [1].
an
The term ‘plasma’ refers to a quasi-neutral ionized gas, primarily composed of photons, ions and free electrons as well as atoms in their fundamental or excited states with a net neutral charge
M
[2]. Plasma is generally categorized as ‘thermal’ when electrons and other gas species are in thermodynamic equilibrium and ‘non-thermal’ when they exist in non-equilibrium. Earlier, cold
d
plasma were generated under low-pressure conditions limiting its applications. However, recent
te
advances in plasma engineering have allowed cold plasma generation at atmospheric pressure
Ac ce p
leading to increased research on cold plasma at various interfaces of life sciences. A summary of major applications of cold plasma technology is shown in Figure 1. Figure 1: Summary of major applications of cold plasma technology
There are various types of cold plasma generation systems used for different applications in the industry. They could range from corona discharges, microwave plasma, radio frequency plasma, inductively coupled plasma, capacity coupled plasma, electron cyclotron resonance plasma and dielectric barrier discharge plasma. Among these, dielectric barrier discharge and jet plasma are the most used for food research owing to their simple, versatile and adaptive designs and working.
Page 3 of 11
Plasma can be generated in any neutral gas by providing sufficient energy for its ionization making plasma chemistry much more complex. For example, air plasma consists of over 75 unique species and more than 500 chemical reactions happening at nano, micro, milli and
ip t
seconds time scales [3]. There is a continuing research in the field of plasma chemistry for
identification of reactive species generated in the plasma and their interaction with the biological
cr
and chemical components of food products. This requires research efforts to understand the
us
mechanisms for microbial inactivation, toxin degradation, or other desirable effects and
an
subsequently leverage such information for food product/process improvement. Applications of cold plasma
M
Specifically for the food industry, current cold plasma research are focused on its applications
te
the following sections.
d
for food decontamination, toxin degradation and packaging modifications which are discussed in
Cold plasma for food decontamination
Ac ce p
Cold plasma has proven an effective non-thermal processing technology for inactivation of various pathogenic and spoilage microorganisms found in the food products. There are various reviews available in literature on application of cold plasma providing a snapshot of progress of cold plasma technology in food processing [4-8]. Although, most of the current studies are still focused on exploring and optimizing the plasma decontamination process conditions for different food products targeting various microorganisms, there has been a significant interest for understanding the plasma inactivation mechanisms for different microorganisms. It was previously reported that reactive oxygen species play the most crucial role in microbial inactivation leading to strong oxidative stress conditions, causing cell damage by lipid
Page 4 of 11
peroxidation, enzyme inactivation and DNA cleavage [9]. Recently, L Han, et al. [10] have reported different inactivation mechanisms for Gram positive and Gram negative bacteria by cold plasma. They showed that cold plasma inactivation of Gram positive bacteria
ip t
(Staphylococcus aureus) was mainly due to intracellular damage and little envelope damage
whereas Gram negative bacteria (Escherichia coli) was inactivated mainly by cell leakage and
cr
low-level DNA damage. A succint review by P Bourke, et al. [11] have summarized the
us
interactions of plasma gas species with a range of microbiological targets along with the advances in the mechanistic insights. These studies clearly indicates the selective and differential
M
mechanistic studies for better understanding.
an
interactions of reactive gas species in the plasma systems emphasizing the need for future
Apart from microbial inactivation, effects of cold plasma on the food quality has been another
d
important aspect drawing attention of food researchers. Cold plasma inactivation of food
te
enzymes have received significant attention in this regard. A review by NN Misra, et al. [1]
Ac ce p
reported that plasma gas species causes loss of secondary enzyme structure due to breakdown of specific bonds or chemical modifications of the side chains and were dependent on power input, degree of exposure, mass transfer between the plasma-liquid phases, structural complexity and stability of the enzymes in their local environment. Further research are recommended for identification of plasma generated reactive species and their interaction with potential microorganisms and food components at molecular level for further mechanistic understanding. Cold plasma for toxin degradation
Page 5 of 11
Natural and synthetic toxins are ubiquitously present in our ecosystem. Toxic compounds such as trypsin inhibitors, saponins, goitrogens, lectins might be inherently present in various food products. Other toxins like pesticides, endocrine disruptors, mycotoxins etc. are also present in
ip t
our food and water system raising concern for consumer health and safety. Currently, there are very limited non-thermal technologies available for control and degradation of toxic compounds
cr
present in food products. Cold plasma has shown promising potential for degradation of various
us
food toxins gaining increased interest from food researchers in past few years. Most of the current research in food products are focused on cold plasma degradation of mycotoxins and
an
pesticides.
M
Mycotoxins are toxic secondary metabolites produced by filamentous fungi contaminating various food products posing serious health risks problems. Many of the mycotoxins have been
d
classified as carcinogenic, mutagenic and genotoxic. The resistance for degradation of
te
mycotoxins by thermal processing and inability to completely inactivate them by conventional
Ac ce p
processing has led to active research for alternative processing technologies. Cold plasma has shown significant degradation of mycotoxins in various food products [12,13]. Researchers are now focusing on optimizing the process parameters to increase the degradation efficiency along with insights into the degradation mechanism [14-16]. Although, cold plasma has been presented as a viable alternative, further studies are required to understands the reaction mechanism in presence of different reactive species along with the toxicity study of degradation products. The use of pesticides is a common agricultural practice which has significantly decreased the crop losses by insects and in turn increasing the yield at a global scale. However, pesticides are also toxic for humans and thus have to be stringently regulated below the residual toxicity limit in all the food products. The use of cold plasma has proven efficient in degradation of many
Page 6 of 11
pesticides in various food products [17-20]. The effectiveness of cold plasma for pesticide degradation has been attributed to the generation of different reactive gas species like ions (H3O+, O+, O−, OH−, N2+), molecular species (O3, H2O2), and reactive radicals (O•, OH•, NO•).
ip t
Future studies are recommended to analyze the degradation efficiency in different classes of
cr
pesticides, degradation mechanism and toxicity of degradation intermediates and products.
us
Cold plasma for food packaging
Cold plasma is being used in the packaging industry for many decades. It has been extensively
an
used for packaging material sterilization, surface etching, surface functionalization, surface activation and surface deposition. Many reviews on the applications of cold plasma for food
M
packaging have been published previously [2,21]. Along with its use for conventional polymers, recently it has been used for surface modification of bio-based films and coatings [22-24]. Some
d
recent studies have also shown the potential of cold plasma to be used for active [25-27] and
te
intelligent packaging materials [28]. Current trends in this area continues with plasma treatment
Ac ce p
of different packaging materials to improve their packaging properties. Conclusions
Cold plasma is an emerging non-thermal technology which has shown potential applications at different interfaces of life sciences. In food industry, its application are mostly focused on food decontamination, improving food quality, degradation of toxins and surface modification of packaging materials. Cold plasma has shown some unique advantages over traditional technologies to offer solutions for current problems in the food industry. However, cold plasma technology is still in its nascent stage and requires further work in system designing, scalability
Page 7 of 11
studies, eco-toxicity studies and mechanistic insights before it could be fully utilized at a commercial scale.
ip t
Reference Papers of particular interest, published within the period of review, have been highlighted as:
cr
• of special interest
us
•• of outstanding interest
M
an
••1. Misra NN, Pankaj SK, Segat A, Ishikawa K: Cold plasma interactions with enzymes in foods and model systems. Trends in Food Science & Technology 2016, 55:39-47. This article is an excellent review of enzyme inzctivation in food and model systems by cold plasma. This paper includes the basics of cold plasma, summarizing studies for important enzymes inactivations along with an insight into the inactivation mechanism.
Ac ce p
te
d
2. Pankaj SK, Bueno-Ferrer C, Misra NN, Milosavljević V, O'Donnell CP, Bourke P, Keener KM, Cullen PJ: Applications of cold plasma technology in food packaging. Trends in Food Science & Technology 2014, 35:5-17. 3. Gordillo-Vázquez FJ: Air plasma kinetics under the influence of sprites. Journal of Physics D: Applied Physics 2008, 41:234016. 4. Misra N, Jo C: Applications of cold plasma technology for microbiological safety in meat industry. Trends in Food Science & Technology 2017. 5. Misra NN, Tiwari BK, Raghavarao KSMS, Cullen PJ: Nonthermal Plasma Inactivation of FoodBorne Pathogens. Food Engineering Reviews 2011, 3:159-170. 6. Niemira BA: Cold plasma decontamination of foods. Annual review of food science and technology 2012, 3:125-142. 7. Surowsky B, Schlüter O, Knorr D: Interactions of non-thermal atmospheric pressure plasma with solid and liquid food systems: a review. Food Engineering Reviews 2015, 7:82-108. 8. Thirumdas R, Sarangapani C, Annapure US: Cold plasma: a novel non-thermal technology for food processing. Food biophysics 2015, 10:1-11. 9. Han L, Patil S, Keener KM, Cullen PJ, Bourke P: Bacterial inactivation by high-voltage atmospheric cold plasma: influence of process parameters and effects on cell leakage and DNA. Journal of Applied Microbiology 2014, 116:784-794. •10. Han L, Patil S, Boehm D, Milosavljević V, Cullen PJ, Bourke P: Mechanisms of inactivation by high-voltage atmospheric cold plasma differ for Escherichia coli and Staphylococcus aureus. Applied and environmental microbiology 2016, 82:450-458. This study shows the differential mode of inactivation for Gram positive and Gram negative bacteria after cold atmospheric plasma treatment. This study also suggests that plasma gas species reactions are primarily dependent on the microbial cell structure and chemical composition. ••11. Bourke P, Zuizina D, Han L, Cullen P, Gilmore BF: Microbiological Interactions with Cold Plasma. Journal of Applied Microbiology 2017.
Page 8 of 11
This is a succint review of previous studies of microbial decontaminations by cold plasma in food and biomedical sciences. This work also critically analyzed the microbiological interactions of plasma reactive species at the cellular level.
us
cr
ip t
12. ten Bosch L, Pfohl K, Avramidis G, Wieneke S, Viöl W, Karlovsky P: Plasma-Based Degradation of Mycotoxins Produced by Fusarium, Aspergillus and Alternaria Species. Toxins 2017, 9:97. 13. Siciliano I, Spadaro D, Prelle A, Vallauri D, Cavallero MC, Garibaldi A, Gullino ML: Use of cold atmospheric plasma to detoxify hazelnuts from aflatoxins. Toxins 2016, 8:125. •14. Sakudo A, Toyokawa Y, Misawa T, Imanishi Y: Degradation and detoxification of aflatoxin B1 using nitrogen gas plasma generated by a static induction thyristor as a pulsed power supply. Food Control 2017, 73, Part B:619-626. This article illustrates the degradation efficiency of aflatoxin by nitogen gas plasma. It also analyzed the effects of plasma process variables on the degradation rate. They also showed that nitrogen gas plasma treatment not only cause degradation of aflatoxin but also reduces the physiological activity of the samples.
Ac ce p
te
d
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an
15. Shi H, Ileleji K, Stroshine RL, Keener K, Jensen JL: Reduction of Aflatoxin in Corn by High Voltage Atmospheric Cold Plasma. Food and Bioprocess Technology 2017:1-11. 16. Wang S-Q, Huang G-Q, Li Y-P, Xiao J-X, Zhang Y, Jiang W-L: Degradation of aflatoxin B1 by low-temperature radio frequency plasma and degradation product elucidation. European Food Research and Technology 2015, 241:103-113. 17. Bai Y, Chen J, Mu H, Zhang C, Li B: Reduction of Dichlorvos and Omethoate Residues by O2 Plasma Treatment. Journal of Agricultural and Food Chemistry 2009, 57:6238-6245. 18. Misra N, Pankaj S, Walsh T, O’Regan F, Bourke P, Cullen P: In-package nonthermal plasma degradation of pesticides on fresh produce. Journal of hazardous materials 2014, 271:33-40. 19. Sarangapani C, O'Toole G, Cullen P, Bourke P: Atmospheric cold plasma dissipation efficiency of agrochemicals on blueberries. Innovative Food Science & Emerging Technologies 2017. 20. Misra N: The contribution of non-thermal and advanced oxidation technologies towards dissipation of pesticide residues. Trends in Food Science & Technology 2015, 45:229-244. 21. Pankaj S, Thomas S: Cold Plasma Applications in Food Packaging. Cold Plasma in Food and Agriculture: Fundamentals and Applications 2016:293. 22. Pankaj SK, Bueno-Ferrer C, Misra N, O'Neill L, Tiwari B, Bourke P, Cullen P: Dielectric barrier discharge atmospheric air plasma treatment of high amylose corn starch films. LWT-Food Science and Technology 2015, 63:1076-1082. 23. Pankaj SK, Bueno-Ferrer C, Misra NN, Bourke P, Cullen PJ: Zein film: Effects of dielectric barrier discharge atmospheric cold plasma. Journal of Applied Polymer Science 2014, 131. 24. Oh YA, Roh SH, Min SC: Cold plasma treatments for improvement of the applicability of defatted soybean meal-based edible film in food packaging. Food Hydrocolloids 2016, 58:150-159. 25. Pankaj S, Bueno-Ferrer C, Misra N, O’Neill L, Bourke P, Cullen P: Effects of Cold Plasma on Surface, Thermal and Antimicrobial Release Properties of Chitosan Film. Journal of Renewable Materials 2016. 26. Clarke D, Tyuftin AA, Cruz-Romero MC, Bolton D, Fanning S, Pankaj SK, Bueno-Ferrer C, Cullen PJ, Kerry JP: Surface attachment of active antimicrobial coatings onto conventional plasticbased laminates and performance assessment of these materials on the storage life of vacuum packaged beef sub-primals. Food Microbiology 2017, 62:196-201. 27. Pankaj S, Bueno-Ferrer C, Misra N, O’Neill L, Jiménez A, Bourke P, Cullen P: Surface, Thermal and Antimicrobial Release Properties of Plasma-Treated Zein Films. Journal of Renewable Materials 2014:1-8.
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28. Pankaj S, Kelly CA, Bueno-Ferrer C, Kerry JP, Papkovsky DB, Bourke P, Cullen P: Application of phosphorescent oxygen sensors in in-package dielectric barrier discharge plasma environment. Innovative Food Science & Emerging Technologies 2016, 33:234-239.
Highlights •
Cold plasma shows promising applications for food industries.
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It can be used for microbial inactivation and toxin degradation in food products.
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Cold plasma can also be used for food packaging materials modifications.
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