Effects of plasma activated solution on the colour and structure of metmyoglobin and oxymyoglobin.

Effects of plasma-activated solution (PAS) on the colour and structure of metmyoglobin (metMb) and oxymyoglobin (oxyMb) were investigated and the relationship between discolouration and structure changes was clarified for the first time. Results showed that the colour of PAS-treated metMb faded first, followed by green discolouration, while PAS-treated oxyMb turned from bright red to reddish-brown and then towards green in the end. It was due to the accumulation of HO, nitrite and nitrate in PAS with prolonging plasma treatment times. Also, the low concentrations of active species in PAS cannot influence the colour and structure of metMb and oxyMb. The accumulation of active species of HO in PAS was the main reason for destructing myoglobin structure and transforming its colour with prolonging treatment time. Therefore, the concentration of HO should be adjusted to a low level for treating red meats as their colour appearance is mainly determined by metMb and oxyMb.