Background Cold plasma is an emerging non-thermal disinfection and surface modification technology which is chemical free, and eco-friendly. Plasma treatment of water, termed as plasma activated water (PAW), creates an acidic environment which results in changes of the redox potential, conductivity and in the formation of reactive oxygen (ROS) and nitrogen species (RNS). As a result, PAW has different chemical composition than water and can serve as an alternative method for microbial disinfection. Scope and approach This paper reviews the different plasma sources employed for PAW generation, its physico-chemical properties and potential areas of PAW applications. More specifically, the physical and chemical properties of PAW are outlined in relation to the acidity, conductivity, redox potential, and concentration of ROS, RNS in the treated water. All these effects are in microbial nature, so the applications of PAW for microbial disinfection are also summarized in this review. Finally, the role of PAW in improving the agricultural practices, for example, promoting seed germination and plant growth, is also presented. Key findings and conclusions PAW appears to have a synergistic effect on the disinfection of food while it can also promote seedling growth of seeds. The increase in the nitrate and nitrite ions in the PAW could be the main reason for the increase in plant growth. Soaking seeds in PAW not only serves as an anti-bacterial but also enhances the seed germination and plant growth. PAW could potentially be used to increase crop yield and to fight against the drought stress environmental conditions.

Plasma activated water (PAW): Chemistry, physico-chemical properties, applications in food and agriculture

Background Cold plasma (CP) is an emerging technology, which has attracted the attention of scientists globally. It was originally developed for ameliorating the printing and adhesion properties of polymers plus a variety of usage domains in electronics. In the last decade, its applications were extended into the food industry as a powerful tool for non-thermal processing, with diverse forms for utilization. Scope and approach This review presents an overview of recent studies on the application of cold plasma in the food industry. Specific areas discussed include microbial decontamination of food products, packaging material processing, functionality modification of food materials and dissipation of agrochemical residues. The application of CP has also been expanded into areas, such as hydrogenation of edible oils, mitigation of food allergy, inactivation of anti-nutritional factors, tailoring of seed germination performance and effluent management. In addition, the paper provides a summary of plasma chemistry and sources, factors influencing plasma efficiency and strategies for augmentation. Furthermore, key areas for future research are highlighted and salient drawbacks are discussed. Key findings and conclusions The recent studies conducted on the interaction of reactive species with food contact surfaces establish plasma processing as an eco-friendly technique with minimal changes to food products, making it a befitting alternative to traditional techniques. Active researches focused on up-scaling for commercial applications are urgently required.

A review on recent advances in cold plasma technology for the food industry: Current applications and future trends

Cold plasma (CP) technology has proven very effective as an alternative tool for food decontamination and shelf-life extension. The impact of CP on food quality is very crucial for its acceptance as an alternative food processing technology. Due to the non-thermal nature, CP treatments have shown no or minimal impacts on the physical, chemical, nutritional and sensory attributes of various products. This review also discusses the negative impacts and limitations posed by CP technology for food products. The limited studies on interactions of CP species with food components at the molecular level offers future research opportunities. It also highlights the need for optimization studies to mitigate the negative impacts on visual, chemical, nutritional and functional properties of food products. The design versatility, non-thermal, economical and environmentally friendly nature of CP offers unique advantages over traditional processing technologies. However, CP processing is still in its nascent form and needs further research to reach its potential.

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Effects of Cold Plasma on Food Quality: A Review

Background Fresh-cut fruits and vegetables have gained much more attention worldwide in the past decades. Due to the increased awareness of consumers in sensorial and nutritional qualities of fresh-cut fruits and vegetables, as well as the serious concerns towards public health caused by foodborne outbreaks owing to inappropriate handling or preservation of fresh-cut fruits and vegetables, fresh-cut industry is in urgent need of new and improved technologies for shelf life extension. Scope and approach In this review the recent development in novel shelf life extension technology applied to fresh-cut fruits and vegetables, including physical, chemical and biopreservation methods are described. These novel technologies better maintain or improve the quality and safety of fresh-cut fruits and vegetables. However, reduction in microbial load without compromising in sensory and nutritional qualities could not be easily achieved by one technique alone. Some combined application of these techniques proved to be very effective in both shelf life extension and microbial inhibition of fresh-cut fruits and vegetables. Key findings and conclusions Future research needs to consider varieties of further combined applications of physical, chemical and biopreservation technologies, which may allow a better maintenance of the fresh-like characteristics of the raw produce. Meanwhile, consumer's acceptance, safety and legal aspects, and commercial availability, such as the efficacy, cost-effectiveness ratio and convenient manipulation, should also be taken into consideration in future studies.

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Recent developments in novel shelf life extension technologies of fresh-cut fruits and vegetables

Biomimetic dynamic membrane for aquatic dye removal.

In the past cold plasma is used for sterilization of sensitive materials and now it is extended to food industries as a novel technology. For years cold plasma processing has been viewed as useful for microbial inactivation while maintaining quality of fresh produce. However, this process is not effective for in vitro model food systems for inactivation of microbes or enzymes which are present in intact tissues, as it is a surface phenomenon. Cold plasma technology is also used to inactivate endogenous enzymes which are responsible for browning reactions particularly polyphenoloxidase and peroxidases. Several research investigations showed a reduced growth of microorganism via different mode of actions by etching phenomenon, cell disruption by electrophoration etc. Plasma technology is considered as modern non conventional technique which is used for the preparation of modified starches, altering its physical and chemical properties. Overall application of cold plasma for microbial destruction on different food substrates like fruits, meat products, cheese etc. was discussed. Besides this, it is also used to alter the germination rate of seeds. It is an eco-friendly process which is used in the preservation of food and other potential applications as an alternative to common techniques.

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Cold Plasma: A novel Non-Thermal Technology for Food Processing

Functional and rheological properties of cold plasma treated rice starch

Cold plasma is an emerging novel non-thermal technology in the sector of food processing. In the present review we will discuss the recent scientific reports on properties of cold plasma treated starches. For industrial use native starch is subject to modification to enhance the properties. This paper reviews on the mechanism of starch modification by plasma reactive species, briefly discussing its effects on properties. The effect of cold plasma on starches depends on the type of feed gas, voltage applied and treatment time. The alteration in the properties is mainly due to depolymerization and cross linking of amylose and amylopectin side chains. After plasma treatment there is decrease in molecular weight, viscosity, and gelatinization temperatures. Plasma etching increased the surface energy and enhanced the hydrophilicity of the starch granules. We can conclude that cold plasma is as alternative technology to modify the properties of starch.

Cold Plasma: an Alternative Technology for the Starch Modification

The aim of this research is to study the effect of low pressure cold plasma on the cooking and textural properties of brown rice at two different power levels (40 and 50 W) and different treatment times (5 and 10 min). Cold plasma processing of foods is an emerging non thermal technology mainly used to change surface properties of substrates and microbial inactivation. Proximate composition, cooking properties and textural characteristics of plasma processed brown rice were investigated. SEM, contact angle and surface energy analysis were done to study the changes in surface morphology of plasma treated rice. It was observed that after the plasma treatment the cooking time was reduced significantly from 29.1 min to 21.1 min with respect to plasma power and time of treatment. The increase in degree of gelatinization of the cooked samples supported the decrease in cooking time. The water uptake was increased from 2.2 to 2.36 g/g after the treatment. Textural parameters showed there is decrease in hardness from 40.47 N to 30.09 N and chewiness. The extent of plasma treatment was observed as decrease in contact angle and increase in surface energy, making surface more hydrophilic and thus rice grains absorbs more water resulting in lesser cooking time. Based on the results it can be concluded that plasma application can significantly change cooking and textural properties. Industrial relevance The present work is suitable for the instant rice production industries. This technology can be used by the industries designing rice cooker. This can also be used by the countries for cooking rice, where resources are scarcity.

Rohit Thirumdas

Papers

Plasma activated water (PAW): Chemistry, physico-chemical properties, applications in food and agriculture

Cold Plasma: A novel Non-Thermal Technology for Food Processing

Functional and rheological properties of cold plasma treated rice starch

Cold Plasma: an Alternative Technology for the Starch Modification

Influence of low pressure cold plasma on cooking and textural properties of brown rice