One key point that warrants further clarification is the interpretation of microbial inactivation patterns in Figure 2. While the study presents a clear trend of microbial reduction with increasing cold plasma voltage and exposure time, the underlying mechanistic explanation could be expanded. Specifically:
i. The paper attributes microbial reduction to the presence of reactive oxygen and nitrogen species (RONS). However, no direct measurement of RONS concentration in the juice matrix is provided. A quantification of these species (e.g., via electron paramagnetic resonance spectroscopy or chemiluminescence) would strengthen the claim that microbial inactivation is primarily due to RONS rather than secondary effects such as local temperature rise or pH changes.
ii. The results show that yeast and mold exhibit a more gradual reduction compared to aerobic mesophiles. While this aligns with previous studies, a discussion on whether this is due to differences in cell wall composition, repair mechanisms, or other intrinsic factors is missing. Would alternative plasma treatment parameters (e.g., pulsed exposure vs. continuous) enhance inactivation of more resistant species?
iii. The study employs ANOVA and Fisher’s LSD test for statistical comparisons, but no power analysis or effect size calculation is reported. Given the variability inherent in biological samples, was the sample size sufficiently large to draw robust conclusions, particularly for microbial subgroups?