Pulsed Light Treatment Effect on Color, Oxidative Stability, and Listeria monocytogenes Population of Sliced Mortadella

Abstract

This study evaluated the effects of high-intensity pulsed light (PL) on sliced mortadella, assessing how the parameters pulse width (1260 to 2520 µs) and number of pulses (one to three) influence color, oxidative stability, and Listeria monocytogenes population. The different PL parameters generated a fluence ranging from 2.64 to 6.57 J/cm² and irradiance ranging from 1046.9 to 1738.8 W/cm². The PL slightly increased the temperature and pH of the samples, and this elevation was well correlated to the higher number of pulses and higher fluence. The color parameter a* was reduced while b* values increased after PL application, with these effects being more significant in treatments with a higher number of pulses and higher fluence. The highest values of TBARS were found in treatments with higher fluence (5.28 and 6.57 J/cm²), which were characterized by the attribute "oxidized color" in sensory evaluation. The different PL conditions reduced the count of L. monocytogenes by up to 1.44 Log CFU/cm². The treatment with a pulse width of 1260 µs, two pulses, fluence of 4.38 J/cm², and irradiance of 1738.3 W/cm² achieved the same efficacy in pathogen reduction as the treatments with higher fluence. Moreover, these PL conditions had a minimal impact on the color and oxidative stability of mortadella, demonstrating an effective balance between microbiological safety and quality preservation.

Keywords: emulsified meat products; lipid oxidation; non-thermal treatment; post-cooking contamination; sensory profile.

Figure 1

Variation in the temperature on the sliced mortadella surface caused by pulsed light (PL) application. Different letters indicate significant differences based on Tukey’s test (p < 0.05). Error bars depict the standard error of the average. Treatments: see Table 1.

Figure 2

Variations in pH of sliced mortadellas caused by pulsed light (PL) application. Different letters indicate significant differences based on Tukey’s test (p < 0.05). Error bars depict the standard error of the average. Treatments: see Table 1.

Figure 3

Changes in instrumental color ((a): L*; (b): a* and (c): b*) and ΔE values (d) of sliced mortadellas caused by pulsed light (PL) application. Significance: ns (p > 0.05); * (p < 0.05); ** (p < 0.01); *** (p < 0.001). Treatments: see Table 1.

Figure 4

Reduction in L. monocytogenes (Log CFU/cm²) of sliced mortadellas caused by pulsed light (PL) application. Different letters indicate significant differences based on Tukey’s test (p < 0.05). Error bars depict the standard error of the average. Treatments: see Table 1.

Figure 5

TBARS values of sliced mortadellas during storage. Different letters indicate significant differences based on Tukey’s test (p < 0.05). Error bars depict the standard error of the average. Treatments: see Table 1.

Figure 6

Generalized Procrustes Analysis (GPA) map for sensory analysis results of sliced mortadellas on day 1 (a) and day 30 (b) of storage. Treatments: see Table 1.