Using Water More Efficiently in Beef Packing Plants

Background

Packing plants use a time-tested approach to clean their facilities. The first step uses high-pressure hot water to remove fat and meat scraps from equipment, floors and walls. Next, surfaces are cleaned using detergent. Finally, sanitizers are used to further reduce bacterial numbers. Processing companies want to reduce water use as part of their environmental goals and to reduce energy bills.

High-pressure water and steam can produce aerosols that capture bacteria and spread them throughout the plant. They can then settle on and cross-contaminate clean surfaces long after the cleaning has been completed, which complicates efforts to effectively clean facilities.

Biofilms are another problem. Biofilms are colonies of bacteria surrounded by a protective layer that firmly attaches them to surfaces and shelters the bacteria from hot water, detergents and sanitizers. Biofilms are hard to remove and are commonly found in hard-to-reach places.

These researchers investigated potential cross-contamination caused by pressurized water aerosols, in-plant biofilms harborage and ways to use less hot water and lower pressure, a particular challenge when trying to clean fat from surfaces. Information generated in this work could improve effectiveness of cleaning, reduction in water usage, as well as improved microbiological safety of meat.

Objectives

• Establish an objective measurement of cleaning and sanitation effectiveness and determine the potential for cross-contamination from aerosols and biofilms.
• Identify conditions that reduce cross-contamination.
• Identify physical and chemical pre-treatments for water that improve cleaning effectiveness and reduce the volume and temperature of water required for cleaning.

What they did

Three studies were conducted. The first two were carried out in a commercial packing facility to establish a baseline of what happens in commercial practice. To quantify cross-contamination from aerosols, over three months researchers collected air, floor drain and conveyor belt surface samples at four points during the cleaning process (i.e., before cleaning, after pressure washing, after detergent, after sanitizer). Bacterial numbers were counted and composition was assessed.

To assess the effectiveness of current cleaning practices against biofilms, TBF300 and Indicon Gel (i.e., rapid commercial biofilm detection kits) were used to identify contamination hotspots on eight groups of surfaces including 16 different items/sites at each of three sampling trips. Swab samples were also collected. The bacteria present were identified and counted, and all samples were assessed for the extracellular polymeric substances that make up biofilms.

A third study was carried out in laboratory to assess efficacy of sanitizers against biofilms. The team used 40 bacterial strains previously collected from meat processing plants. The strains were incubated with meat juice under dynamic temperatures for up to six days simulating meat plant operations, and the degree of the biofilm formation was measured by biomass and cell numbers. The biofilms were exposed to two cleaners (i.e., Tergazyme or PowerFoam Plus) and two sanitizers (Decon 7 or BioDestroy) that have been developed for biofilm removal. The toughest biofilms were subjected to a combination of treatments.

Next, the research team tested different water “preconditioners,” such as alkali compounds, surfactants and enzymes, for their ability to break down fat and protein to help to effectively clean greasy surfaces using less hot water.

Finally, a biodegradable, cost-effective biosurfactant (i.e., rhamnolipids) was tested for its ability to remove fat from surfaces at reduced temperatures and to prevent attachment of biofilm former to surfaces.

What They Learned

The first study found that washing with pressurized water created aerosols that moved bacteria from floor drain surfaces to other surfaces and increased bacterial numbers on conveyor belt surfaces. Foaming reduced bacterial numbers, but sanitizers did not reduce bacterial numbers. Acinetobacter dominated the microbiota of all samples throughout facility cleaning and sanitation. A bacterial translocation model predicted that the drain surface was a significant contributor to the initial microbiota on conveyor belts but was replaced by air after a pressurized water washing step.

The second study found that the commercial rapid biofilm test kits could not detect biofilms very well in a commercial plant environment. Floor mats had the highest total bacterial count, while floor drain surfaces had the highest Pseudomonas count. Of 162 sites examined, 46.9% harbored biofilms (mostly from floor mats, tanks for dipping utensils and wall corners). The biofilms contained 35 bacterial genera, including those that are of importance to food safety and product shelf life. Pseudomonas, Acinetobacter and Escherichia were commonly found on most surfaces and in biofilms and non-biofilm samples.

The third study found that biofilms form differently in meat juice than they do in laboratory media. Of the two sanitizers, Decon 7 eradicated biofilms most effectively (100%). In contrast, biofilm strains were still recovered after treatment with BioDestroy (23%), PowerFoam Plus (46%) or Tergazyme (54%). The effectiveness of BioDestroy for biofilm removal was improved when a pre-treatment step using PowerFoam Plus and Tergazyme was included.

The first study also showed that a targeted combination of proteases and lipase enzymes at lower temperatures (40-50°C) than currently used (55°C) significantly reduced organic residues and lowered ATP levels by approximately 93%, indicating a substantial improvement in surface cleanliness. When further enhanced with enzymes that disrupt biofilm structure, the treatment achieved near-complete removal of Escherichia coli O157:H7 biofilms.

A concentration of 0.5–1% rhamnolipid biosurfactant emulsified fat as effectively as 2.5% PowerFoam Plus. At 40°C, all rhamnolipid concentrations (0.1–1%) significantly outperformed water in fat removal. Rhamnolipid pre-conditioned surfaces also significantly reduced biofilm-forming E. coli O157 attachment.

What It Means

Meat processing facilities put tremendous efforts into cleaning and sanitation. However, washing with pressurized water may compromise subsequent cleaning efforts, and biofilms are rather common on post-cleaned surfaces. Biofilms in meat processing facilities do not always present themselves in “slimes” and cannot be reliably detected by the rapid methods currently available. Improvements in the practicality, cost-effectiveness and reliability of detection are crucial for biofilm control in commercial environments. A two-step approach incorporating a preliminary step such as equipment soaking can improve biofilm removal in meat processing facilities, ultimately strengthening food safety and reducing the risk of bacterial persistence. Enzyme-based formulations or biosurfactants have the potential to transform sanitation practices in meat processing by improving the ability and efficiency of water to emulsify fats at lower operating temperatures.