# In-Process Microbial Load Dynamics and Production Environment Microbial Hygiene in the Manufacturing of Low-Processed Vacuum-Packed RTE Pork Bar with Dried Plasma

**Authors:** Paweł Pniewski, Dorota Chrobak-Chmiel, Michał Tracz, Krzysztof Anusz, Elżbieta Hać-Szymańczuk, Edyta Lipińska, Małgorzata Ziarno, Anna Pyziel, Kinga Domrazek, Agnieszka Jackowska-Tracz

PMC · DOI: 10.3390/foods15040618 · 2026-02-09

## TL;DR

This study examines how microbes spread during the production of vacuum-packed pork bars, identifying key contamination points and offering insights to improve food safety.

## Contribution

The study provides empirical data on microbial dynamics in low-processed RTE meat production, highlighting step-specific contamination risks.

## Key findings

- Microbial counts increased by 1.5–2.3 log CFU/g during early processing steps, indicating critical contamination-prone operations.
- Environmental monitoring identified contamination hotspots on frequently handled surfaces, especially in pre- and post-lethality stages.
- Despite effective baking, low-level microbial reappearance during packaging and maturation suggests post-process contamination risks.

## Abstract

Low-processed ready-to-eat (RTE) meat products are highly vulnerable to microbial contamination, yet data on in-process dynamics remain limited. This study investigated microbial dynamics and environmental hygiene during the production of vacuum-packed RTE pork bars containing dried plasma, with a focus on identifying process-inherent contamination risks. Samples were collected at successive processing stages and from food-contact and non-food-contact surfaces. Process hygiene was assessed using indicator organisms (Aerobic Plate Count, Enterobacteriaceae, lactic acid bacteria, yeast and mold, E. coli, S. aureus counts), while food safety relevance was addressed by monitoring Listeria monocytogenes and Salmonella spp. Microbial counts increased by approximately 1.5–2.3 log CFU/g between early processing steps, indicating that these operations are critical contamination-prone steps. Environmental monitoring revealed contamination hotspots on frequently handled surfaces, highlighting the vulnerability of pre- and post-lethality stages. Despite the baking achieving a mean microbial reduction of ~3 log CFU/g, consistent with effective thermal processing, low-level microbial reappearance during packaging and maturation indicated the potential for post-process contamination. The results demonstrate that production-inherent factors largely drive microbial contamination patterns and may persist even in facilities operating under implemented GHP, GMP, and HACCP-based procedures, highlighting step-specific limitations rather than system failure. By providing empirical data on in-process microbial dynamics, this study supports both scientifically based and risk-based approaches within Food Safety Management Systems, offering transferable insights applicable to similar RTE meat production environments. The findings may assist food business operators in optimising targeted control measures and strengthening risk-based decision-making in low-processed RTE meat production.

## Linked entities

- **Species:** Listeria monocytogenes (taxon 1639)

## Full-text entities

- **Diseases:** yersiniosis (MESH:D015009), hemolysis (MESH:D006461), Listeriosis (MESH:D008088), salmonellosis (MESH:D012480), microbial (MESH:D015163), smoking (MESH:D015208), poisonings (MESH:D011041), injury to (MESH:D014947), ROP (MESH:C536382), campylobacteriosis (MESH:D002169), infections (MESH:D007239), deaths (MESH:D003643)
- **Chemicals:** TEMPO (MESH:C003959), sodium lactate (MESH:D019354), water (MESH:D014867), agar (MESH:D000362), glucose-1-phosphate (MESH:C031590), lactate (MESH:D019344), ethidium bromide (MESH:D004996), tagatose (MESH:C030192), sugars (MESH:D000073893), salt (MESH:D012492), oxygen (MESH:D010100), stainless steel (MESH:D013193), ribose (MESH:D012266), arabitol (MESH:C014999), trehalose (MESH:D014199), esculin (MESH:D004929), sodium acetate (MESH:D019346), xylose (MESH:D014994), agarose (MESH:D012685), sorbates (MESH:D013011), mannitol (MESH:D008353), carbohydrates (MESH:D002241), saturated fatty acids (MESH:D005227), rhamnose (MESH:D012210), amino acid (MESH:D000596), nitrites (MESH:D009573), Half-Fraser liquid medium (-)
- **Species:** Ovis aries (domestic sheep, species) [taxon 9940], Enterovirus B (no rank) [taxon 138949], Asaia sp. PC (species) [taxon 1837740], Listeria (genus) [taxon 1637], Saccharomyces cerevisiae (baker's yeast, species) [taxon 4932], Escherichia coli (E. coli, species) [taxon 562], Salmonella (genus) [taxon 590], Enterobacteriaceae (enterobacteria, family) [taxon 543], Prescottella equi (species) [taxon 43767], Enterovirus C (no rank) [taxon 138950], Homo sapiens (human, species) [taxon 9606], Leptospira sp. AB (species) [taxon 103236], Staphylococcus aureus (species) [taxon 1280], Listeria monocytogenes (species) [taxon 1639]

## Figures

2 figures with captions in the complete paper: https://tomesphere.com/paper/PMC12939944/full.md

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Source: https://tomesphere.com/paper/PMC12939944