Purpose: The objective of this research was to examine the sanitizing effects of white distilled vinegar solutions to improve the quality and shelf-life of leafy greens by enumerating aerobic microorganisms, coliforms, Escherichia coli, yeast, and mold.
Methods: To determine the efficacy of vinegar as a sanitizing agent we obtained mixed greens and romaine lettuce samples from local farmers. Vinegar solution (1.25% and 2.5% acetic acid) was prepared in a salad spinning device for home use. The lettuce was submerged for 30 sec, spun for 45 sec and allowed to air dry for 1 min. Each sample was stomached with sterile 0.1% peptone, diluted and plated on appropriate media. Aerobic Plate Counts (APC), E. coli/coliforms, and yeast and mold were evaluated for the samples. The microbial counts on the lettuce were evaluated pre- and post-intervention.
Results: The vinegar solutions of 1.25% and 2.5% acetic acid reduced APCs on mixed greens by ~1 log CFU/g and on romaine by ~2 log CFU/g. The E. coli and coliforms counts were reduced on mixed greens and romaine by ~0.5 log CFU/g and ~1.75 log CFU/g, respectively. The intervention reduced yeast and mold counts by ~2 log CFU/g and ~1.5 log CFU/g on both mixed and romaine lettuce samples, respectively.
Significance: These results demonstrate that vinegar can reduce microbial contamination and possibly improve the shelf-life of leafy greens. Furthermore, this can help small farmers who may not have the means to use industrial washers to sanitize fresh produce.