# Application of image analysis combined with regression models to estimate the reduction of Escherichia coli and Salmonella spp. on vegetable surfaces after washing

## TL;DR

This study shows how surface area and roughness of vegetables affect bacterial adhesion and how lactic acid washing reduces harmful bacteria like E. coli and Salmonella.

## Contribution

The study introduces a novel method combining image analysis and regression models to predict bacterial reduction on vegetables during washing.

## Key findings

- Washing with 2.0% lactic acid reduced bacteria from 8.74 to 2.92 log CFU/m².
- Surface area (A) had the strongest correlation with bacterial adhesion (r values 0.764–0.993).
- Surface roughness (R) and fractal dimension (FD) also correlated with bacterial load but less strongly.

## Abstract

Escherichia coli, a bacterium indicating improper hygiene practices during food production, is commonly found in the intestines of humans and animals, while Salmonella spp. are dangerous bacteria that cause typhoid fever and severe diarrhea. These pathogens have been found in fresh vegetables. This study investigated how the vegetable surface characteristics influenced bacterial adhesion. The reduction of bacteria during the washing process was assessed using different concentrations and types of chemicals. The relationships between variables obtained from image analysis techniques and bacterial adhesion on vegetable surfaces were also evaluated. The most effective way to inhibit bacteria was by washing with 2.0% lactic acid, with bacterial reduction from an initial concentration of 8.74 to 2.92 log CFU/m2. Pearson’s correlation with the highest r value was surface area (A) with values ranging from 0.764 to 0.993, followed by surface roughness (R) with values between 0.019 and 0.986, and Fractal dimension (FD) with values between − 0.510 and − 0.992. The correlation between A and the number of bacteria (E. coli and Salmonella) was the highest, with surface area influencing bacterial adhesion to the vegetable surface. Greater surface roughness was associated with a higher initial bacterial load, making the A value a good predictor of changes in bacteria during washing with organic acids at various concentrations.