Introduction
Plasma-activated water (PAW) is produced when water is treated with cold atmospheric plasma (CAP). It has a very high disinfectant capacity, antibacterial efficacy, and eco-friendly nature. It causes little to no modifications to the foodstuffs. The process has successfully demonstrated its effectiveness against a broad range of microorganisms on a wide variety of food items. Hence, this technology can cause a great change in securing food quality and safety in food processing industries.
Plasma-Activated Water (PAW): Process, Application and Significance
Plasma-activated water (PAW) is a potential microbial disinfectant that can extend the shelf life of various food products. Food Processing Industries can use it in the treatment of meat and fish products, fruits and vegetables, cereal products, etc. The treated food products do not show any substantial change in the biochemical properties, the technology promises a safer alternative for food safety.
Process of Formation of PAW
When regular or Tap water is exposed to a non-thermal plasma, Plasma-activated Water (PAW) is produced. This process generates Reactive Oxygen and Nitrogen Species (RONS) that dissolve into the water and create a solution with unique cleansing and antimicrobial properties. It is also produced by passing air through a plasma field and then mixing that activated air with water, using only electricity, air, and water as inputs.
Application of Plasma-Activated Water on Food Products
Plasma is the fourth fundamental state of matter apart from solid, liquid, and gas. It is rich in species such as electrons, UV, ions, free radicals, and excited molecules. Plasma-activated water (PAW) is produced by treating water with plasma. When the water molecules interact with plasma-generated particles, they generate many reactive species. These species exhibit remarkable biological activities in biomedical and agricultural applications. It controls bacterial growth and inactivates bacteria when applied to food products such as fresh fruits and vegetables. These products include grapes, goji berries, kiwifruit, potatoes, and shiitake mushrooms.
Killing Microbes
The biochemical activity of PAW results in the dissolution of various primary and secondary reactive species present in food in the form of chemical and biological agents. This occurs as the cell wall of microbes breaks down due to the physical stress on microorganisms through an acidic pH and an increase in redox potential and conductivity.
Significance of the Plasma-Activated Water Treatment
Maintains Food Quality
PAW maintains or sometimes improves the functional value of food products. It leads to microbial disinfection and extension of shelf-life.
Eco-Friendly
The PAW treatment does not inculcate any chemical preservative. Hence, it promotes an eco-friendly preservation of food products.
Pesticide Degradation
It is the most important feature of PAW. It can wash out the pesticide residues from fresh vegetables and fruits, making them healthy to be consumed.
Limitations of PAW Treatment
Limited Scientific Literature
There is a lack of scientific literature on the mechanism of microbial inactivation in the PAW process. This is because the process is complex. Similarly, the mechanism of interactions between reactive species and food components is still unknown.
Food Quality
As the reactive nature of ROS/RNS with food constituents is not clear, scientists believe that it might form new compounds impacting the quality of food.
Conclusion
According to the Food and Agriculture Organization (FAO) report, in Asia alone, a 33.4 % loss or wastage of fresh produce postharvest is recorded. Postharvest decay is mainly caused by microorganisms. Hence, it raised the need for affordable and adequate microbiological detection and elimination from farm to fork. Fresh or fresh-cut fruits and vegetables serve as carriers for food-borne microorganisms as these products have high water and nutrient content. This microbial contamination often leads to outbreaks of food-borne disease worldwide each year. Other methods of reducing contamination are either very costly or not apt as they change the taste and color of the food articles. Amid these challenges, Plasma-Activated Water (PAW) treatment has emerged as a viable alternative for food safety.