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on August 23, 2007

Go with the one-way flow

Eliminating product crossovers and backtracking

It is imperative that finished product be protected from cross-contamination.

A basic element of a petfood safety program is a plant schematic that depicts the flow of people and products. Process and product flows are important considerations in the development, implementation and maintenance of a plant's HACCP (hazard analysis critical control points) program. Understanding employee and product flow helps identify potential product contamination points and then develop the means to prevent that contamination from occurring.

Food products, including petfoods, typically undergo a process to reduce the presence of pathogens. This process may involve cooking (hence the term cook side vs. raw side), pasteurization, washing and so forth. It is imperative that finished product be protected from cross-contamination (e.g., situations where allergen ingredients, additives or raw ingredients could come into unplanned contact with finished product).

The risk of cross-contamination is greatly reduced through the elimination of product crossovers and backtracking. Ideally, a one-way flow should be maintained so finished products do not enter back into the raw-product side.

People flow

Employees can act as vehicles for transporting microbial contamination. This contamination can be carried on their clothing, shoes and tools. For this reason, plant management often segregates employees between the raw side of production and the cooked side of production.

Segregation can more often than not be achieved through the use of different employee entrances, travel paths and uniforms between the raw and cooked sides of production.

In the absence of employee segregation, other controls such as foot baths, hand washing and uniform change areas between raw and cooked sides of production will help reduce cross-contamination risks.

Product flow

Raw materials may be contaminated by a variety of pathogens so they must not make contact with finished product. Ideally, there is segregation between raw material and finished product storage and handling areas. In addition, there should be separate routes for raw material and finished product travel. Any area where these routes cross over should be assessed to determine if cross-contamination is a risk. For example, raw meat traveling in a tote may result in contamination of the floor. If a tote with finished product travels across that same floor, the contaminants will likely end up on the tote's wheels and subsequently on the product itself.

Using the plant schematic

A plant schematic diagram that indicates the flows of finished and raw products as well as employee traffic is an essential component of your company's HACCP program. The schematic must include the flows of all ingredients and packaging materials from the moment they are received through storage, preparation, processing, packaging, finished product holding and shipping. Employee movement throughout the establishment, including change rooms, washrooms and lunchrooms, must also be identified. This diagram should be a plant's primary tool for identifying potential cross-contamination hazards. Once identified, these hazards can be addressed and controlled though the development of the remaining elements of the HACCP program.

Pre-extrusion processing

When designing a pre-extrusion processing system, David Corley of Midwest Process Solutions (www.midwestprocesssolutions.com) recommends that you consider the following points.

1. Be sure to properly receive and store your raw materials prior to blending. Ensure that tramp metal detection and QA systems are monitored frequently to avoid any costly production issues.

2. All storage bins need to be properly designed for first in-first out mass flow and consistent discharge. There are special designs corresponding to materials handled.

3. All coarse grains should be ground using a hammermill into at least four to five pieces so they will act as marbles in the mixer. All other materials need to be properly screened to ensure consistency and uniformity prior to blending.

4. It is extremely important to accurately feed your materials into your mixer. Be sure to utilize properly designed feeders that will feed consistently and not bridge. Most petfood processors utilize loss-in-weight feeders for this purpose.

5. The mixer needs to be designed for process flexibility and speed. Some paddle style mixers can consistently mix major and minor ingredients as fast as 30 seconds per batch. Be sure to consider ease of cleanout and loading when selecting a mixer. Cycle time is an important consideration.

6. Most petfood manufacturers grind with a hammermill after mixing to ensure a uniform mixed meal goes to the extruder. It is important to design the hammermill air system so the meal is not heated more than 10 degrees Fahrenheit over ambient during grinding. It is also important to properly design your feed system to the grinder for consistent hammermill performance. There have been recent advances in hammermill technology that allow for improved consistency in mixed meal granulation.

7. Managing the delivery of dry feed to the extruder is most important for tight ingredient and moisture control. If these key process parameters are not controlled, improper extrusion can result, costing processors significantly in unacceptable product. A high-precision loss-in-weight feeder system is typically used to feed the extruder. Once a predictable dry feed delivery system is utilized, then other ingredient feeds (such as moisture addition, minor ingredients, pigment and alternative liquid addition) can be coordinated with the extruder dry feed system on a ratio basis. Recent advances in loss-in-weight feeder technology include special feeder designs and digital communications to the host processor.

Simple and repeatable manufacturing techniques allow you to operate consistently and profitably.

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