MA
or PL. The combined application of PL þ MA caused higher cell
damage against both microorganisms than those individual treatments.
In accordance, significant structural changes leading to
modification of cytoplasmic content and disruption of cell membrane
were observed. Significant changes were also observed in the
cytoplasm of L. innocua and E. coli inoculated on fresh-cut watermelon
treated with malic acid alone. Micrographs exhibited clear
zones that are likely to be indicative of a pH decrease, being more
pronounced in L. innocua cells (Figs. 3b and 4b).