Performance Evaluation of colorimetric nano-sensor aminated graphene oxide - bromophenol blue based ‎on Whatman paper in determining of the oxidation quality of fish feed kept in cold storage condition ‎

In the present study, to evaluate the oxidation quality of fish meal stored at refrigerator temperature for 6 ‎months, a colorimetric nano-sensor aminated graphene oxide - bromophenol blue based on Whatman paper ‎was used. The results showed that the amount of moisture increased from 7.19% to 9.37% and ash content ‎increased from 7.29% to 8.04% during storage (P <0.05). The amount of changing in fat and protein contents ‎showed that fat content decreased from 12.87% to 10.53% and protein content decreased from 54.51% to ‎‎52.37% and showed decrease procedure during the storage period (P <0.05). Peroxide value (PV) increased ‎during the period, and the maximum amount of that was at the end of the storage period with 6.1 meq O2 / kg ‎lipid (P <0.05). The amount of thiobarbiotic acid (TBA) showed increased procedure and finally reach to 3.86 ‎‎(mg MAL / kg meal) (P <0.05). The color changes (ΔE) of the used nanosensor were increased during storage ‎period and changed from 29.04 to 52.67 (P <0.05), and also changed from green to blue and detectable by the ‎naked eye. Pearson correlation coefficients between PV and TBA indices with color changes index (ΔE) were ‎‎0.93 and 0.89, respectively. The results of this study suggest that the use of colorimetric nano-sensor aminated ‎graphene oxide - bromophenol blue based on Whatman paper with a simply color change process can be a ‎novel approach in determining the oxidation quality of fish feed during storage.‎