Food Product Design: Catalog Showcase - April 2005 - Avoiding Bacterial Problems: The Top 10

April 2005

Top-10 lists aren't just handy for the FBI or entertainers; they can work for those concerned with food safety, as well. However, while David Letterman might be able to conclude his Top-10 list with a nod to the No. 1 reason, microbiology is more selective than comedy -- the most important issues in one industry might not have the same level of importance in another. Some industries have few bacterial problems, while others must worry about the entire food supply chain.

So, from the home office in Northbrook, IL, we offer the following 10 ways to avoid bacterial problems in a food- and beverage-manufacturing environment.

No. 1: outside the box
It's important to examine the entire supply chain and to know what's outside of the plant's four walls even if an HACCP plan is in place, since this might or might not have been done. This is the farm-to-table concept.

This includes knowledge about the farming practices used to produce the raw materials. Remember that we import 50% of the food consumed in the United States. Are the practices in foreign producing areas the same as when the process was established? This can apply to the United States, as well. Organic farming, for example, poses microbial risks associated with natural fertilizer that don't exist with chemical fertilizers. Evaluate the cleaning, loading and unloading of trucks and other means of transport.

One reason for a HACCP plan is to identify what is and is not under control: Control is defined as the ability to change the results. If a manufacturer does not have control over a particular risk factor, what can it do to add positive control for that risk?

One case in point is the potential contamination of RTE products between processing and packaging. Manufacturers can add positive control of certain nonspore-forming pathogens to the process after packaging with ultra-high-pressure (UHP) technology. According to Errol Raghubeer, Ph.D., vice president for microbiology and food technology, Avure Technology, Kent, WA, this commercial process -- used for many products, including guacamole salad, lunch meat and chicken strips -- has achieved a five-log reduction in Listeria monocytogenes and Salmonella without changing the final product's flavor or texture. Currently, these products are distributed refrigerated, but Avure is working with private industry and the Department of Defense under the Dual Use Science and Technology (DUST) program to produce shelf-stable products. They hope to have FDA approval for commercial use for these in two more years.

Rocelle Clavero, Ph.D., technical director, Silliker Laboratories, Homewood, IL, mentions that it is important to develop sound specifications for raw ingredients, primary packaging materials and finished products, as well as establishing a means to verify compliance. This would include the method of transport: inbound and outbound. We have become so preoccupied with documentation that, many times, no one is verifying what the document actually represents. Does it matter if a hopper car has a washing certificate if the certificate is not based on a validated cleaning procedure?

No. 2: environmental control
It's critical to know and understand the environment and the actual processes involved in a food's production, suggests Kerri Harris, Ph.D., executive director, International HACCP Alliance, College Station, TX. Environmentally speaking, this encompasses more than bacterial load; it includes people, equipment and traffic patterns.

A written employee-hygiene program for companies to teach to each employee at orientation is a must, according to Michael Bushaw, executive director, ASI Food Safety Consultants, Inc., St. Louis. Note the distinction of "at orientation," meaning before a new hire prepares food. Training is personal and must reflect the languages and education levels of the plant workers. Employees must demonstrate knowledge of the program, and they should also take an annual refresher course.

Another way to ensure a healthy environment is to examine airflow. Regularly inspect the air-handling systems and filters. Check for mold growth or a sour smell inside ductwork. HVAC units create condensate which, when mixed with food dust, creates a rich microbial growth environment. Condensate on the outside of the ductwork can drip onto product or equipment. Sensitive, open product areas should have positive air pressure. Ventilating systems in sensitive areas should have the ability to be sanitized.

Material flow also can cause problems. Forklifts carry what they pass through into the next area -- not just on the tires, but also from dirty water dripping from the wheel wells. For traffic flow, look at the total people flow, including supervisors, office workers, laboratory personnel, maintenance workers and contractors. Consider restricting access to certain areas. Sanitizing baths can help, but only if used and maintained.

Sewer design is basic, but often overlooked. Problems encountered include: drains higher than the surrounding floor; drains that can't carry peak water discharge; drain pipes that are too small or partially clogged, causing water from one area to back up into another; drain-trap depth that doesn't take the area's air pressure or vacuum into their design; unprotected drains that are over process equipment, such as a drain for the floor above hidden in a drop ceiling; and unplugged drains in areas with infrequent washing.

No. 3: clean and easy
Properly designed and fabricated equipment costs more initially, but ends up being more economical to maintain and operate in the long run. Companies can follow certain existing equipment standards, such as those published by 3-A Sanitary Standards, Inc., McLean, VA, and NSF International, Ann Arbor, MI.

Just because a machine is certified for one type of product doesn't guarantee ease of cleaning for another application. Machine operators should review the machine drawings. Get installation drawings (to scale) showing the walls, piping, floor drains, ventilation, utilities and access doors to the process area. Experienced operators should review the machine drawings. Send a qualified person to examine the machine before it is shipped. For hand-washed equipment, the machine needs to be taken down and reassembled. For clean-in-place (CIP), the total system must support CIP.

No. 4: process validation
Although process failures reach the market less often these days, they do still occur. If the product is commercially sterile and produced under the low-acid/acidified food GMPs (Title 21 of the Code of Federal Regulations, Parts 113 and 114), it should have a validated process developed by a qualified processing authority. This is also true of other thermally processed foods and beverages. The validated process must be followed all the time and revalidated after equipment changes.

No. 5: proper operation
Written operating procedures and employee-training programs for proper equipment operation are crucial to producing safe food. But they're not enough. The actual process should be reviewed on a regular basis. Are trained operators running the machines? Are the current procedures being followed? Is the documentation being completed in a timely manner? Is the supervisor qualified for this area? What is the function of quality control, and is the QC system integrated into the process? Who is responsible for equipment cleaning and maintenance? How are problems reported, and who makes sure they are corrected? According to Bushaw, a good system will be in writing, and each person's training and evaluation requires documentation. A current list of qualified operators and supervisors should be readily available.

With continuous operations, workers must know how to shut down the equipment. Clavero cautions that a shutdown for periodic maintenance can cause unanticipated problems, such as the warming of a freezing-tunnel environment that results in bacterial growth that later might contaminate product.

No. 6: clean-up problems
John Sofos, Ph.D., professor of food microbiology, Department of Animal Science, Colorado State University, Fort Collins, notes the importance of validating the sanitation program before and after cleanup to ensure that it's working. A base line must be established to measure progress as the program is modified.

According to Clavero, in-plant standard operating procedures "may not be followed as written and/or the employees are not adequately trained." Physical inspections and swabs of equipment will verify if procedures are followed and effective. She also says that many plants with a CIP system believe that turning the system "on" is all that's required for clean equipment and mentions the need to schedule regular breakdowns of the equipment for inspection and maintenance. This includes replacing the gaskets, looking for buildup and checking for corrosion. She says it's especially important to inspect CIP systems that have junctions.

Make sure that the washing procedure does not cause problems. Look for and eliminate drip and splatter, and improve ventilation to prevent condensation. Prevent cross-contamination by washing equipment from different processes in different areas. Do not wash parts on the floor.

Different sanitizers are available, but they can hurt product quality if not used properly. Consider using ozone in the final rinse. This safe, effective, nonresidual sanitizer disrupts biofilm and kills most pathogens when used at low levels in cold water on hard surfaces. EPA and FDA have approved ozone for direct food use.

Bushaw notes that there should be a written water-testing program that is followed on a regular basis to check for standard plate counts (SPCs) and coliforms. Be sure that the program is extensive enough to detect problems throughout the operation.

No. 7: suitable storage
Proper storage techniques involve more than maintaining correct temperature. Another practice, storing raw and processed products separately, helps prevent cross-contamination. Bushaw suggests storing clean vegetables only with other clean vegetables, and that shell eggs never be stored over other products. Clavero recommends the clear separation of raw materials from in-process products from finished products. Consider the effect that excess inventory might have on cross-contamination. Don't forget to inspect outside warehousing.

Maintaining product below 45?F helps control bacteria, but maintaining this temperature throughout the area requires adequate airflow. If a cooling system was designed to hold already-cooled product, but is being used to cool warm product, it's probably inadequate to protect the product.

No. 8: rework analysis
Rework is frequently implicated in many recalls -- not only bacterial problems, but also with allergen contamination. Review the rework procedure to eliminate the possibility of passing on past problems to future production. Establish a documented method to track rework. Why is the product reworked, and how will it be reprocessed in a way that eliminates any contamination?

No. 9: verify testing
Harris paraphrases a colleague in saying that the problem with evaluating any testing program is whether it was set up to find or not to find a problem. Someone asked what I thought of a Listeria-testing program that pulled one sample a day from a 250,000-unit lot. It represents the latter.

All verification programs start with calibration of whatever measuring devices are important: thermometers, gages, pH meters, scales, etc. When using National Institute of Standards and Technology (NIST) criteria, go to the NIST website (www.nist.gov) and read any recommendations for calibrating that type of instrument.

Verifying the sanitation program will reinforce the GMP and sanitation programs. To have a sanitation-validation program, a manufacturer must decide what organisms to use as an indicator. First select the organism(s). Sometimes, the type of organism is specified in a government regulation. An SPC might not indicate cleanliness, as many organisms do not show up on SPC plates.

Now pick a method that is as fast as possible that does not lead to an inordinate number of false positives and is specific and valid for the product matrix. This method needs to be validated on each system, especially with rapid methods. Divide a sample into two parts. Then treat one with the new method and another with a more-traditional method. In addition to selecting the proper parameters to monitor, process validation must confirm that the sampling program used is valid.

Results that indicate deficiencies need to lead to corrective-action plans that will eliminate the deficiency in the future. This could be refresher training of the employees to a reevaluation of a particular SOP. All of this requires documentation. Remember, with base line data processors will always know if the system is improving or regressing.

No. 10: category evaluation
Clavero warns against introducing new products or formulations without performing a comprehensive assessment of microbial risk during the product development and/or concept phase. How does a manufacturer measure the business risk of an unknown? It takes dedication to learn as much as possible about the new product. If companies do not allocate that time, the chances of product failure dramatically increase.

The scope of this article cannot cover every risk that might potentially exist. But it does provide 10 steps in the right direction.

Bruce Floyd established Process Systems Consulting, Iowa City, IA in 1997 after working more than 30 years in the food-processing industry. He has had extensive experience in sanitation, quality control, regulatory relations, and product and process development (domestic and international), and specializes in adapting ingredient and manufacturing specifications to the equipment available to create the desired finished product. A graduate of Georgia State University, Atlanta, he has successfully completed all areas of the Better Process Control School, has been qualified as an instructor by the International HACCP Alliance, and has been certified as an FPA-SAFE auditor by the Food Processors Association.

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