Application of citric acid and mild heat shock to minimally processed sliced radish: Color evaluation

• Effects of citric acid and 50 °C thermal treatments on sliced radishes were examined.
• Single hurdle and hurdles in series were performed prior to 10 d storage.
• L*, a*, b*, chroma, total color difference, and Color Index were determined.
• 0.3% citric acid or 2 min thermal treatment at 50 °C was best single hurdles.
• 1 min 50 °C thermal treatment + 0.3% citric acid was the best two-hurdle treatment.

The aim of this research was to study the effects of two hurdle technologies, citric acid application (CA) at 0.3%, 0.6% and 0.9% and thermal treatments (IT) for 1, 2 and 3 min at 50 °C, on the color of radish slices over 10 d of refrigerated storage. Contribution of the hurdles and their interactions were evaluated by examining the treatment effects on the following parameters: chromatic coordinates (L*, a* and b*) and the indices: chroma (ΔC*), total color difference (ΔE) and Color Index (CI*).The chromatic parameters for fresh radish (control samples) were L0 = 69.43 ± 0.62, a0 = −0.46 ± 0.05 and b0 = 5.37 ± 0.37, while the calculated color indices were chroma = 5.39 ± 0.36, ΔE = 0 and CI* = −1.19 ± 0.17. Regarding control samples, the b* values showed an increasing trend during storage, which was associated with browning of the slices. Both ΔE and ΔC* values presented similar trends as reported for b*. Based on statistical analysis of the parameters and indices tested, the single hurdle application of low citric acid concentration (0.3%) or intermediate immersion time (2 min) at 50 °C minimized the radish slices color changes during storage. However, better results were obtained when two hurdles in series were applied. According to analysis, the treatment T7 (1 min IT, 0.3% CA) was selected as the best treatment to improve the retention of typical natural color of the minimally processed sliced radishes.