The fabrication and kinetic modeling of a new time–temperature label based on paraffin wax and black carrot anthocyanin for monitoring fish products
This study was conducted to fabricate and model a time–temperature label (TTL) based on paraffin wax and black carrot anthocyanin for monitoring fish products. A polar homogeneous wax was prepared using water, liquid paraffin, paraffin gel, cetyl alcohol, and citric acid. The prepared polar solid homogeneous wax was positioned on a paper smeared with pH-sensitive anthocyanin. The wax melted after being heated and flowed on pH-sensitive anthocyanin. The pH-sensitive anthocyanin smoothly showed color changes after contacting with wax. The efficiency of TTL was evaluated in the samples of farmed rainbow trout slices. Thiobarbituric acid reactive substances (TBARS), total volatile basic nitrogen (TVB-N), and sensory analyses were evaluated at the temperatures of −5, 5, 15, and 25 °C. The obtained values for TBARS, TVB-N, and color changes were plotted vs. time for all the temperatures and finally modeled by the Arrhenius equation, and activation energy values (Ea) were calculated. The fabricated TTL did not show color changes at the temperatures of −5 and 5 °C, but it showed color changes at the temperatures of 15 and 25 °C. The values of TBARS and TVB-N were significantly higher and the data for sensory analyses were smaller for the samples stored at the temperatures of 15 and 25 °C compared to those for the samples stored at −5 and 5 °C (P < 0.05). The obtained value for Ea (118.622 kJ mol−1) was in the required range for quality indices in fish products. In conclusion, the fabricated TTL shows color changes at higher temperatures parallel to higher TBARS and TVB-N and lower sensory panels.