Abstract
The scavenging activity of myoglobin toward peroxynitrite (PON) was studied in meat extracts, using a new developed electrochemical method (based on cobalt phthalocyanine-modified screen-printed carbon electrode, SPCE/CoPc) and calculating kinetic parameters of PON decay (such as half-time and apparent rate constants). As reactive oxygen/nitrogen species (ROS/RNS) affect the food quality, the consumers can be negatively influenced. The discoloration, rancidity, and flavor of meat are altered in the presence of these species, such as PON. Our new highly thermically stable, cost-effective, rapid, and simple electrocatalytical method was combined with a flow injection analysis system to achieve high sensitivity (10.843 nA µM−1) at a nanomolar level LoD (400 nM), within a linear range of 3–180 µM. The proposed biosensor was fully characterized using SEM, FTIR, Raman spectroscopy, Cyclic Voltammetry (CV), Differential Pulse Voltammetry (DPV), and Linear Sweep Voltammetry (LSV). These achievements were obtained due to the CoPc-mediated reduction of PON at very low potentials (around 0.1 V vs. Ag/AgCl pseudoreference). We also proposed a redox mechanism involving two electrons in the reduction of peroxynitrite to nitrite and studied some important interfering species (nitrite, nitrate, hydrogen peroxide, dopamine, ascorbic acid), which showed that our method is highly selective. These features make our work relevant, as it could be further applied to study the kinetics of important oxidative processes in vivo or in vitro, as PON is usually present in the nanomolar or micromolar range in physiological conditions, and our method is sensitive enough to be applied.
Highlights
For the food industry and for the consumers, it is very important to monitor the quality and freshness of raw meat
Cobalt phthalocyanine was already used in the literature as a bio-mimetic material for biosensors [36]
We demonstrate here that the Co2+ /Co1+ redox couple is more effective than the high potential electrochemical methods reported in the literature for the electrochemical detection of PON, as it offers better selectivity
Summary
For the food industry and for the consumers, it is very important to monitor the quality and freshness of raw meat. One pathway of alteration is the scavenging activity of myoglobin toward nitro-oxidative species (such as peroxynitrite, PON). The formation of metmyoglobin can alter the flavor due to lipid and protein oxidation [4]. The lack of metmyoglobin (MbFe3+ OH2 or metMb) reducing enzymatic systems in meat after slaughter determines the irreversibility of the oxidation processes of myoglobin [5]. The color changes are a sign of these processes, and some possible oxidation pathways are described in Figure 1 [6]. Nitrites and nitrates are two of the decomposition compounds of peroxynitrite. Distinguishing between these species is important for meat quality
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