Synergistic Antimicrobial Effect of Garlic and Oregano Extracts in Edible Coatings for Fresh-cut Lettuce Preservation

Fresh-cut lettuce is highly susceptible to microbial spoilage and enzymatic browning, which significantly limits its shelf-life and poses food safety risks. Edible coatings incorporated with natural antimicrobials offer a promising, eco-friendly preservation strategy.

This study evaluated the synergistic antimicrobial effect of garlic (Allium sativum) and oregano (Origanum vulgare) extracts incorporated into a sodium alginate-based edible coating to extend the shelf-life of fresh-cut iceberg lettuce.

Fresh-cut lettuce samples were treated with four coating formulations: Control (distilled water) Sodium alginate base only Alginate with individual extracts (garlic or oregano) Alginate with a combination of garlic and oregano extracts (1:1 ratio) Samples were stored at 4 c0 for 12 days. Microbial analysis (Total Aerobic Plate Count, yeast, and mold), weight loss, firmness, total phenolic content, and visual color changes (Delta E) were assessed at 3-day intervals.

The combination coating containing both garlic and oregano extracts exhibited a significant synergistic effect (p < 0.05), reducing the total aerobic bacterial count by 2.4 Og text CFU/g compared to the control by day 12. This dual-extract formulation also effectively suppressed yeast and mold growth. Furthermore, the synergistic coating significantly minimized moisture loss, maintained tissue firmness, and delayed enzymatic browning without negatively impacting the sensory attributes of the lettuce.

The integration of garlic and oregano extracts into an edible alginate coating demonstrates a potent synergistic antimicrobial and preservative effect. This formulation represents a viable, natural alternative to synthetic preservatives for maintaining the quality and safety of fresh-cut produce in the food industry.