## 4 Plasma Technology for Crop Sustainability and Food Processing
Many researchers have reported the inactivation of phytogenic bacteria on seeds and the upregulation of pathogen resistance genes in plants after cold atmospheric pressure plasma exposure [49,87]. Plasma-activated water irrigation induced the tomato plant defense system against _Xanthomonas vesicatoria_ (Xv), although antimicrobial effects of the PAW against _X. vesicatoria_ were not observed [88]. The induced expression of the PAL transcript upon PAW irrigation may be associated with the induced tomato defense system [88]. Harvesting, storage, and processing are crucial steps in the agricultural system. Food processing involves the transportation, cleaning, sorting, blending, and milling of crops to convert them to food. Technological innovations for the post-harvest storage and food processing stages are required to increase the food security index of the current agricultural system. Cold atmospheric or low pressure plasma is a promising technology to decontaminate and improve the shelf life of fresh and processed food products [108]. Several studies have reported plasma effects on post-harvest storage and food processing (Table 3). Microbial contamination during processing, packaging, and storing is a major problem that decreases shelf life, deteriorates taste, and causes food poisoning. Plasma treatment efficiently reduces the microbial contaminants on fruit, vegetables, and other edible products in a time- or dose-dependent manner, as summarized in a recent review [109]. The antimicrobial potential of plasma is well demonstrated by various cold atmospheric or low pressure plasma sources \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Plant Species** & **Plasma Source** & **Feed Gas** & \begin{tabular}{c} **Treated** \\ **Stage** \\ \end{tabular} & **Improved Effects** & **Reference** \\ \hline Mandarins & \begin{tabular}{c} Microwave N\({}_{2}\), He, N\({}_{2}\) \\ + O\({}_{2}\) plasma \\ \end{tabular} & \begin{tabular}{c} Nitrogen (N\({}_{2}\)), helium \\ (He) and nitrogen \\ (N\({}_{2}\))/oxygen (O\({}_{2}\)) \\ mixture \\ \end{tabular} & Mandarin & \begin{tabular}{c} Increased \\ antioxidant activity \\ and phenolic content \\ \end{tabular} & [104] \\ \hline \multirow{3}{*}{Mung bean sprouts} & \multirow{3}{*}{\begin{tabular}{c} Plasma-activated \\ water \\ \end{tabular} } & \multirow{3}{*}{Air} & \
\begin{tabular}{c} Mung bean \\ sprout \\ vegetables \\ \end{tabular} &
\begin{tabular}{c} Reduced microbial \\ contamination \\ without changing \\ polyphenolic and \\ flavonoid contents. \\ \end{tabular} & [105] \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._(gliding arc discharge, cold plasma argon jet, helium jet, microwave-generated plasma, and dielectric barrier discharge (DBD) plasma), microbes (_Erwinia carotorova, Salmonella anatum, Salmonella enterica serovar Stanley, Salmonella enteritidisis, Escherichia coli, Erwinia amylov, Listeria monocytogenes, Clavibacter michiganensis subsp. Spedonicus, Dickya solani, X. campestris pv. Campestris, P. atrospecificum, Pectobacterium carotororum subsp. Carotororum, Pseudomonas fluorescens, Pseudomonas marginals, and P. carotororum_), and fresh products (lettuce, tomatoes, carrots, cherries, figs, black peppers, strawberries, onions, radishes, cress, alfalfa seeds, grapes, bananas, and almonds). Studies have also shown that plasma cannot completely eradicate the microbial load but does prevent the microbes from multiplying [109]. An industrial-based DBD prototype efficiently removed the microflora load of fresh cherry tomatoes and prolonged the shelf life during storage [110]. Plasma-processed air can also reduce the microbial loads of fresh fruits/vegetables and packaged foods [111]. In the food processing industry, conventional techniques such as pasteurization, drying, and freezing, and newer physical strategies, such as ultraviolet (UV) irradiation, X-ray irradiation, ozone washing, and high-pressure processing, have been used to maintain food quality. However, these processing techniques have some drawbacks [112].