Purpose: This study was conducted to investigate the effectiveness of zein and chitosan-acids based coatings in reducing population of Salmonella spp. on tomatoes while preserving fruit quality.
Methods: Zein-based coatings with 0-20% cinnamon and mustard essential oil and chitosan-acids coatings with 60 ppm mustard essential oil were developed and applied to cherry tomatoes. Populations of Salmonella spp. on the fruit were enumerated during post-coating storage. Additionally, quality of tomatoes was evaluated.
Results: Our results showed that population of attenuated S. Typhimurium inoculated on the smooth surface and stem area of the tomatoes were reduced with the increasing essential oil concentration and storage times. S. Typhimurium population on the smooth surface of tomatoes was reduced by 4.59 and 2.84 log CFU/g by the zein coatings with 20% cinnamon and 20% mustard oil, respectively, 5 hours after coating. The coatings reduced population of S. Typhimurium by 1.47-6.31 log CFU/g on the stem area of the fruit during 7 days storage at 10 °C. The chitosan-acids coatings reduced more than 3.56 log CFU of S. Stanley, S. Panama and S. Poona on the whole tomatoes. The loss of firmness during storage was retarded by all of the coatings except the zein coating with 20% mustard oil which induced fruit softening. Color, soluble solids content, pH, titratable acidity and ascorbic acid of tomatoes were not consistently affected by any of the coating treatments.
Significance: Our results suggest that the zein or chitosan-based coatings containing essential oils may be used to enhance microbial safety and quality of tomatoes.