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Protective Pectin-Zinc-Thymol Coating to Minimize Salmonella Typhimurium, Enteritidis, and Montevideo in Cherry Tomatoes
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DOI：10.3390/polysaccharides7030091.png)
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Abstract
En 中文
Cherry tomatoes are highly susceptible to Salmonella contamination during pre- and post-harvest handling, leading to foodborne illness outbreaks and significant economic losses. Edible coatings incorporating natural antimicrobials offer a promising alternative to conventional chemical treatments for enhancing food safety while maintaining produce quality. This study developed and evaluated a pectin-based edible coating enriched with zinc nanohydroxide-thymol nanohybrids (ZnNH-T) for controlling Salmonella contamination and extending shelf-life of cherry tomatoes. ZnNH-T nanohybrids were synthesized via precipitation, followed by thymol intercalation, and characterized by SEM. Four coating formulations were prepared: pectin alone (P), pectin-thymol (PT), pectin-ZnNH (PNH), and pectin-ZnNH-T (PNHT). Antibacterial activity of the four coatings was first screened in vitro by disc diffusion against six S. enterica serovars; three serovars (Typhimurium, Enteritidis, and Montevideo) showing a statistically significant, coating-dependent inhibition response were selected for the postharvest assay. Cherry tomatoes were coated and dip-inoculated with three Salmonella serotypes (Typhimurium, Enteritidis, and Montevideo) at approximately 105 CFU/mL and stored at 25 °C for 12 days. Antimicrobial efficacy, antioxidant activity (ABTS assay), and physicochemical quality parameters (weight loss, color, pH, and total soluble solids) were evaluated. Zinc nanohydroxides were successfully synthesized, as observed in SEM morphology. ABTS radical scavenging activity of filmogenic solutions was highest for PT (92.4%) and moderate for PNHT (65.9%), while P and PNH showed minimal activity (20.1% and 17.8%, respectively). PNHT coating achieved an approximately 2-log CFU/g reduction in Salmonella populations compared to uncoated controls over 12 days of storage, demonstrating sustained antimicrobial efficacy. Coated tomatoes exhibited significantly reduced weight loss (8% for PNHT vs. 13% for control), better color retention, lycopene content, maintained firmness, and stable pH and TSS values compared to uncoated controls. The pectin-ZnNH-T coating system represents a novel multifunctional approach for enhancing cherry tomato safety and quality. The use of thymol from the layered hydroxide structure, combined with zinc ion antimicrobial effects, provides sustained pathogen reduction while maintaining desirable physicochemical properties. This natural, biodegradable coating technology has potential for commercial application in fresh produce preservation.
Keywords:
edible coating
pectin
zinc layered hydroxide
thymol
<i>Salmonella</i>
cherry tomato
food safety
antimicrobial nanohybrid
Journal
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IF:
5.5
Papers:
228
Citations:
696
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