# Innovation in the Processing of Native Round Fish: A Readjustment of the Processing Workflow for Salmonella spp. Control in a Fish Processing Plant in the State of Mato Grosso

## TL;DR

This study shows that adjusting the fish processing workflow can significantly reduce Salmonella contamination, improving food safety for consumers.

## Contribution

A modified processing workflow was developed and tested, achieving complete elimination of Salmonella in fish processing.

## Key findings

- The modified processing flowchart completely eliminated Salmonella spp. contamination.
- An adapted version of the modified flowchart reduced contamination from 56.7% to 3.3%.
- Separating dirty and clean processing areas reduced cross-contamination effectively.

## Abstract

The presence of Salmonella spp. in fish poses a risk to public health, even though this bacterium is not part of the natural microbiota of fish. The main source of contamination is the production and processing environment. In Brazil, washing with chlorinated water at 5 ppm is required, but this measure is not always effective. This study was conducted in a fish processing plant in the state of Mato Grosso to identify failures in the processing flowchart and propose improvements. Three treatments were tested: the conventional process, a modified flowchart, and a modified flowchart adapted to the plant’s structure. The modified treatment completely eliminated Salmonella spp., while the adapted version reduced contamination from 56.7% to only 3.3%. The main change was the physical separation between dirty areas (gill and scale removal) and clean areas (evisceration and filleting), reducing cross-contamination. The results show that simple adjustments in the process can significantly increase the safety of the final product. Applying these measures on an industrial scale may contribute to the production of fish that is safer from a hygienic and sanitary standpoint for the consumer.

Salmonella spp. is a pathogen detected in fish, although it is not part of its microbiota; the production and processing environment is the main source of contamination. Brazilian legislation recommends 5 ppm of free residual chlorine for fish washing, but Salmonella can still be present. The objective of this study was to evaluate flaws in the processing flowchart and propose adjustments to reduce Salmonella spp. on the fish surface. Ninety samples were analyzed in a fish processing plant in Mato Grosso, divided into three treatments: (1) conventional processing, (2) modified flowchart, and (3) modified flowchart adapted to the specific plant conditions. Treatment 2 completely eliminated Salmonella spp., while treatment 3 reduced contamination to 3.3%, compared to 56.7% in conventional processing. The success of the modified treatment was only possible due to the main changes implemented in the process, which included the separation of dirty areas (responsible for gill and scale removal) and clean areas (designated for the careful removal of viscera without rupture and for filleting). No statistical difference was found between treatments 2 and 3 (p = 1, CI 0.00000–39.00055), suggesting that the adjusted flowchart can be implemented on a large scale to ensure food safety (OR = ∞, CI = [7.655, ∞], p < 0.001). This study highlights the effectiveness of the adjusted flowchart in reducing Salmonella spp. contamination in fish, with treatment 2 resulting in a complete absence of contamination. Treatment 3 maintained low contamination levels, demonstrating practical applicability in meatpacking plants.