Effects of lauroyl arginate ethyl (LAE) on pathogen inactivation and quality attributes of spinach leaves

Lauroyl arginate ethyl (LAE), a cationic surfactant, exhibits antimicrobial activity against various bacterial strains. This study aimed to evaluate the efficacy of LAE washing treatment for the decontamination of spinach leaves. Spinach leaves were spot-inoculated with Escherichia coli O157:H7 and Listeria monocytogenes to a level of 7.06 and 6.78 log(10) CFU/g, respectively. Results showed that E. coli O157:H7 and L. monocytogenes on spinach decreased by 6.05 and 5.88 log(10) CFU/g, respectively, after LAE solution washing at 5.0 mg/mL for 10 min, significantly higher than the 1.69 and 1.52 log(10) CFU/g of sterile distilled water (SDW). Additionally, the bacterial load in wash water decreased to below the detection limit, demonstrating a cross-contamination prevention capacity of LAE in spinach washing. In comparison with SDW-washed samples, LAE washing did not adversely affect the color parameters (L*, a*, b*, chroma, and hue angle), chlorophyll contents, firmness, and total soluble solids of spinach leaves. The total phenolics and flavonoids contents of SDW-washed spinach leaves were 0.995 mg gallic acid equivalents/g fresh weight and 1.517 mg rutin equivalents/g fresh weight, respectively. Furthermore, the total phenolics and flavonoids contents of spinach were not significantly affected by the LAE washing treatment. In addition, LAE washing also caused no significant changes in the antioxidant properties of spinach samples as measured by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method and ferric-reducing antioxidant power (FRAP) assay. In summary, LAE washing may be an effective method to improve the microbiological safety and quality characteristics of fresh produce.

Automated summary

The study evaluated the efficacy of Lauroyl arginate ethyl (LAE) washing treatment for decontamination of spinach leaves. Results showed that LAE washing significantly reduced the levels of Escherichia coli and Listeria monocytogenes on spinach leaves, without causing adverse effects on color, nutrient content, and antioxidant properties.