  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.
