1*Aeshna Sinha, 2Gautam Kumar
1 Assistant Professor, RIMT University, School of Agricultural Sciences and Technology, Mandi Gobindgarh, Punjab-147301
2 Livelihood Specialist, BRLPS, Vidyut Bhawan, 1st & 2nd Floor, Bailey Road , Patna, Bihar-800021 * Corresponding author- [email protected]
Introduction
Fruits and vegetables are important components of an individual's nutritional framework as they offer essential minerals, vitamins, and fibers and thus form an integral part of a well-balanced diet. In the present era, a pressing global concern pertains to food waste exerting a detrimental effect on both the environment and food security. From the environmental perspective, the improvidence of food resources has led to the depletion of natural assets and contributed to ecological degradation. Recognizing the gravity of this issue, ambitious steps should be taken to reduce food waste, which will not only increase the accessibility of fresh produce but will also reinforce food security.
The persistent demand for this high-quality perishable food has spurred the exploration of effective methods to extend food products' shelf-life and quality preservation. Thermal processing methods are effective in decontaminating foods from microbial attack, but it has been marred by certain issues, including physico-chemical degradation as well as taste alteration. Non-thermal methods such as cold plasma technology is an alternative and more efficient method of preserving and extending the shelf-life of food products and maintaining their nutritional value & flavor. This technology is known for its low energy consumption and effectively targets specific microorganisms or enzymes. Additionally, cold plasma does not leave any toxic residues, thus making it completely safe and environmentally friendly.
Cold plasma requires a low-energy input suitable power source, a specialized carrier gas, and electrodes. Since cold plasma cannot penetrate the food items, microbial inactivation happens on the product's surface with no impact on the raw food's internal nutritional or compositional functions
Principles and mechanism of cold plasma technology
Cold plasma is generated at lower pressure and energy levels (1–10 eV). The given energy dissociates the gas into a plethora of reactive species resulting in the production of electrons, ions, free atoms, molecules, reactive oxygen species (ROS), reactive nitrogen species (RNS), and electromagnetic radiations like UV. ROS includes ozone, monoatomic oxygen, and superoxide anions, while RNS includes excited nitrogen, monatomic nitrogen, and nitric oxide. These species exhibit dynamic properties capable of inducing physical and chemical alterations in food and modifying the food matrices, thus enhancing the qualitative value of food.
Application of cold plasma technology
The microbial decontamination in food through cold plasma involves the interaction of reactive species viz. radicals and reactive molecules, with the cell membranes and cellular functions of microbes. NO and NO2 damage the cells of microorganisms by lipid peroxidation and denaturation of proteins & enzymes. Additionally, generated UV photons impair DNA replication, modify the nucleotide base, and cause nucleotide oxidation, which inactivates the microbes. Furthermore, cold plasma-treated foods have observed damaged cells, cell bursting, pore formation, cell leakage, and cytoplasm shrinkage in microbes under electron microscopy.
Cold Plasma therapy is effective for mild surface decontaminating foods and packaging materials. It inactivates both vegetative cells and spores of microbes present on food surfaces. Plasma can also be utilized for the surface disinfection of packaging materials, eliminating microbes and their spores.
Fruits and vegetables are ingested raw; therefore, concerns of safety and quality are paramount. Cold plasma can be employed for surface disinfection as an in-package treatment as well as fresh-cut produce. Cold plasma treatment alters the mechanical properties of packaging films by etching and cross-linking the film surface. The mechanical properties of packaging films are improved by the ions released on the film's surface by breaking C-C and C-H bonds on the film's surface. Also, the free radicals released through plasma bombardment on the film's surface result in forming bonds with surface radicals and participating in chain reactions. Figure 1 demonstrates the diagrammatic representation of cold plasma application in the food industry.
According to the literature, cold plasma is one of the most effective strategies for the inactivation of several harmful bacteria found in food products. Gram-positive bacteria are inactivated mainly through intracellular disruption and envelope damage, while Gram-negative bacteria are inactivated through DNA mutation and cell leakage.
Plasma therapy also affects the endogenous enzymes by inactivating the browning enzymes of fruits and vegetables. Cold plasma treatment has shown a promising effect on the elimination of certain harmful components found naturally in some foods, including lectins, saponins, inhibitors, trypsin, and goitrogens as well as other hazardous substances such as pesticides, endocrine disruptors, and mycotoxins. ROS and RNS released in cold plasma play a significant role in the breakdown of pesticide residues found on the surface of fruits and vegetables. Cold plasma significantly destroys the mycotoxins present in numerous foods, presenting a major danger to consumer health and safety.
Conclusion
Cold Plasma treatment of food products has been regarded as a novel method in the food industry. Its ability to generate various reactive gases at room temperature assists in microbial decontamination, inactivation of endogenous enzymes, qualitative preservation of food, and retention of functional properties. More research is desired in this area as the impact of cold plasma on allergens and anti-nutritional factors is still little understood. More scientific research is encouraged to gain a thorough understanding of cold plasma technology and its potential applications in the future.
References
- Bora J, Khan T, Mahnot N. K. (2022). Cold plasma treatment concerning quality and safety of food: A Review. Curr Res Nutr Food Sci 2022; 10(2).
- Farooq S, Dar AH, Dash KK, Srivastava S, Pandey VK, Ayoub WS, Pandiselvam R, Manzoor S, Kaur M (2023). Cold plasma treatment advancements in food processing and impact on the physiochemical characteristics of food products. Food Sci Biotechnol. 16; 32(5):621-638. doi: 10.1007/s10068-023-01266-5.
- Nikzadfar, M., Kazemi, A., Abooei, R. et al. (2024). Application of Cold Plasma Technology on the Postharvest Preservation of In-Packaged Fresh Fruit and Vegetables: Recent Challenges and Development. Food Bioprocess Technol. https://doi.org/10.1007/s11947-024-03380-6.
Further Reading
Non-thermal plasma (NTP) for the improvement of food safety and quality