Extraction of Energetic $N_2$ Neutrals for Efficient Plasma Food Processing

Abstract: Low-temperature plasma (LTP) processing is a green and flexible food processing technology with only known limitation of low energy efficiency. Three established fundamental mechanisms of plasma food processing includes: i) physical damage to membranes and internal cellular components due to bombardment of energetic ions: ii) radicals and charged species led chemical reactions: iii) and radiation-induced modifications. In this investigation, we present a new mechanism of generation and extraction of energetic $N_2$ neutrals from glow discharge plasmas for efficient food processing. For nitrogen dc glow discharge plasma we demonstrate by experiment selective generation and extraction of energetic $N_2$ neutrals and $N_2^+$ ions for treatment of different food samples. Using numerical simulations, the plasma processing parameters are defined for selective extraction of $N_2$ or $N_2^+$ species with specific energies. Treatment of native finger millet flour or ragi flour (Eleusine coracana) with selectively extracted energetic $N_2$ neutrals, with an estimated average energy of 34.20 eV, resulted in improvement of shelf-life and functional properties. Additionally, this processing technique achieved high energy efficiency of ~ 46%. This method of food engineering has advantages of control over active species generation, high power efficiency, reduced processing cost, and chemical-free. Therefore, it opens up wide possibilities in plasma food processing for global food security and food safety.