(P02-054-23) The Synergistic Antibacterial Effects of Chitosan-coated Resveratrol and Quercetin Nanoparticles for Extended Shelf Life and Preserved Nutrition Values of Strawberries

Objectives: Fresh fruits and vegetables are popular as healthy foods. However, many of them are highly perishable. A short shelf life, nutrient and freshness loss, as well as associated foodborne illness, are problems that must be addressed. Current trend in food safety and public health is focusing on the use of natural antimicrobials. Trans-resveratrol (R) and quercetin (Q) have antimicrobial properties. However, they have low solubility that limits their bioactivities and applications. Nanoencapsulation can overcome this issue. The objectives of this work are to encapsulate R and Q into biocompatible nanoparticles (NPs), to investigate their antibacterial effect and mechanisms, and to evaluate their impacts on shelf-life, and nutritional values when coating them on strawberries.

Methods: R and Q encapsulated NPs (RQ-NPs) were made using R, Q, soy phosphatidylcholine, Kolliphor, and α-tocopherol acetate. R-NPs and Q-NPs were made using the same method. Chitosan (CS) was coated on R-NP, Q-NPs, and RQ-NPs to make CS-R-NPs, CS-Q-NPs, and CS-RQ-NPs, respectively. The S. enteritidis, L. monocytogenes, E. coli, and S. aureus were used to evaluate the antibacterial activity and mechanisms of free R, free Q, and all NPs. After coating strawberries with free R, free Q, or different NPs, the shelf life, and nutritional values (vitamin C content, total phenolic levels, and total antioxidant capacity) of strawberries were investigated.

Results: RQ-NPs compared to R-NPs or Q-NPs, or free R and Q significantly inhibited the growth of the abovementioned 4 bacteria in a synergistic way. CS coating further enhanced the antibacterial activities of RQ-NPs against these bacteria by 23%, which was associated with changing the expression levels of bacterial genes involved in oxidative stress (such as rpoS, soxR), genomic damage (such as recA), and biofilm functions (such as fnbA and fnbB). Moreover, strawberries coated with CS-RQ-NPs compared to non-coating control had doubled shelf life, and had 3-, 2-, and 3-fold higher vitamin C content, total phenolic levels, and total antioxidant capacity on day 5 at room temperature, respectively.

Conclusions: This research provides innovative approaches for safeguarding foods, preserving nutrients, and reducing foodborne-related disease outbreaks.

Funding Sources: Funding from College of Health Solutions, Arizona State University