Collaborative project: Plasma-treated water as ice for the reduction of the microbial load of aquaculture products: Extension of shelf life, delay of melanosis – Subproject B (PlasEis)

Aquaculture is a sustainable alternative to wild-caught fish and contributes to the demand for products such as fish and shrimps. However, product safety must be ensured during the storage and transportation of aquaculture products in order to achieve the longest possible shelf life for the food. Thereby, spoilage caused by microorganisms is a problem (food waste). Aquaculture owners are particularily dependent on getting the fish or seafood to the end customer as quickly and hygienically as possible in order to ensure regional and sustainable profitability due to the effort involved in production, e.g. high energy and water costs. Until now, fish and seafood has only been stored on ice made from tap water. But the need for additional options to extend shelf life is increasing. Thus, plasma-treated water as ice can be an alternative. Compared to ozone or UV, the antimicrobial effectiveness of physical plasma is not limited to just one active component. Plasma is characterized by the formation of various reactive nitrogen and oxygen species such as singlet oxygen, hydrogen peroxide, nitrite and nitrate, which themselves have an antimicrobial effect or are involved in it. In addition, no toxic chemicals are required. The generated reactive species are transformed to harmless substances after mediation of the antimicrobial effect. Additionally, the inhibition of enzymes that cause melanosis (brown discoloration) in shrimps by plasma-treated water as ice is being investigated. Through the technical combination of an ice machine with a plasma source, a system is being established that produces an actively antimicrobial and enzyme-inhibiting ice that increases the shelf life and marketability of aquaculture products and makes supply chains safer in order to secure and expand sales markets.