Food Safety Magazine

PROCESS CONTROL | February/March 2005

From Aseptic to Zip Pouch: Basic Packaging Material & Line Control

By Doug Peariso

From Aseptic to Zip Pouch: Basic Packaging Material & Line Control

It’s no secret that consumer demand for more convienient, value-added and environmentally friendly food containers has driven rampant innovation in food packaging design. New types of food packaging components and materials, the processes by which these are manufactured into packaging, and the processes these packaging materials undergo on the food manufacturing production line, all have an impact on the plant’s process control systems. More importantly, how effectively these elements are managed will have a significant impact on the food company’s ability to achieve its overall food safety and quality assurance objectives.

Whether you’re using aseptic packaging, modified atmosphere packaging (MAP), glass bottles or plastic zip pouches, there are three process control points at which food manufacturers can ensure food packaging safety. The first is design control, the stage at which the food manufacturer and the packaging material supplier work in concert to ensure that the packaging will be both functional and food-safe in terms of the design aspects. Second, the food manufacturer’s source control system is key to ensuring that the materials that arrive at the plant meet both critical food safety and quality specifications. Finally, the food manufacturing operation’s own internal control system ensures safely packaged final product through activities such as in-process package testing, inspection and auditing. Information derived from the food company’s external focus systems, such as consumer feedback and complaint data and retailer rejection or reclamation center records, can be used to verify that the packaging system is in control.

By employing basic food safety monitoring and controls at these three critical supply and production steps, as well as by utilizing external focus data for verification, the food manufacturer will enhance the company’s ability to produce safe product. There should be no compromise in food safety attributes when utilizing innovative package materials and novel designs that maintain the expected quality and convenience attributes that consumers expect.

Design Control: R&D Input
Although the research and development (R&D) process within the packaging supplier’s operation falls outside of the spectrum of the direct process control systems in place in a food manufacturing plant, processors can provide valuable input to suppliers at the package design stage. Food processors need to ensure that during the R&D stage package designers use packaging materials that are not inherently dangerous from a food safety perspective, provide the necessary barrier to hazards or other undesirable inclusions to the product, and that the final package design is capable of being manufactured efficiently. The latter is important because if the package supplier produces an innovative new zip bag but the bags do not function well when run on the food production lines the packaging, innovative as it may be, is ultimately of little benefit to the food processor’s business plan.

From a food safety control perspective, the food processor can assist the package designer in identifying potential physical, chemical and biological hazards that may be associated with or result from the use of new packaging materials and components. For example, if the package is intended to house a product for use by a toddler, it is advantageous to consider whether this new packaging will contain a component that could be defined as a small part under 16 CFR 1501.4, such as a packaged toy premium, and assess whether that part constitutes a choking hazard or is defined under 21 CFR as a non-nutritive foreign object. Similarly, if the food manufacturer requires tamper-evident packaging, the package bands should be assessed to ensure that they cannot be inadvertently reintroduced into the product or present a choking hazard if they become detached.

Other design elements that need to be considered and factored in prior to commercialization include potential chemical hazards that may occur due to the composition of the packaging material itself. For example, glues and dyes, while external to the package, may inadvertently be provided a pathway into the food product through the packaging material, at which point they may have become indirect additives. It is important to consider if some level of temperature abuse, exposure to moisture or other mishandling of the packaging material will allow microorganisms to breach the package and thus adulterate the product.

Certainly, controlling the pathways of biological contamination of a product from pathogens of public health concern is of the utmost importance, and toward that end, packaging manufacturers must conduct due diligence as they develop process control specifications (i.e., sealing temperatures) for the food processor. These critical specifications should include the shelf life of the packaging material itself; i.e., the point at which the package will display poor physical characteristics and/or poor barrier traits that promote or allow spoilage organisms or provide entry of pathogens through the material. During the design control phase, the packaging supplier will be expected to provide the food processor with the hermetic sealing characteristics of the packaging and recommend robust, repeatable test methods used for ensuring that the package is assembled correctly in the manufacturing environment.

Source Control: Supplier Specs
The best time to prevent a food safety hazard from adversely affecting your operation is before materials and products get through your door—and well before you have to employ the necessary in-plant controls. In essence, source control is a strategy to ensure that the supply of packaging material that you receive in fact meets the specifications necessary to make a safe and wholesome finished product. This begins by selecting a reputable packaging supplier that is committed to food safety and total quality management in their own facilities. Before contracting with a packaging supplier, the food manufacturer or a reputable third-party agent should conduct a facility audit of the packaging plant to ensure that there are adequate controls in place to govern the manufacture of your product. Adequate controls include strict adherence to Good Manufacturing Practices (GMPs), documented quality control systems, adequately trained personnel, proper use of statistical techniques (SPC), a traceability program, and, if the package manufacturer has one (as many increasingly do), the Hazard Analysis and Critical Control Points (HACCP) program. A thorough audit of these control mechanisms at the packaging materials supplier’s facility raises the level of confidence that the supplier is able to produce packaging that meets the food manufacturer’s specifications time and time again. Also important is the contract between the food company and the packaging materials supplier. From the processor’s perspective, this should include:

• The critical tolerances and component formulations necessary to deliver the packaging product to your door in a manner that makes it manufacturable and safe in a finished food product.

• Clearly identified acceptable quality levels (AQLs), usually defined as “critical,” “major” and “minor” package nonconformances.

• A proviso giving the food manufacturer packaging design and formulation control rights such that if the packaging material manufacturer would like to incorporate another material, change the structure or critical dimensions of the packaging, or use another facility to manufacture the packaging they will inform the food company in writing prior to making any such changes

• Dispute language that clearly identifies who will be responsible for any damages (rework, recall or product loss) if a material failure occurs.

The packaging supplier also needs to issue the food company ongoing letters of guarantee, which can be referenced as an on-site document for the food manufacturer when requested by the U.S. Food and Drug Administration (FDA), or the U.S. Department of Agriculture’s Food Safety and Inspection Service (USDA FSIS). Information that should be included:

• The name of the supplier and any relevant contact information

• The brand name, or other unique designator for the supplied material

• A statement that the material complies with the relevant sections of the Federal Food, Drug & Cosmetic Act (and any other applicable regulations, particularly the sections of the Code of Federal Regulations pertaining to indirect food additives/suitable packaging materials) and that it’s safe and will not adulterate the product under the intended conditions of use

• A statement specifying any applicable limits regarding conditions of use (temperature, humidity, pH, etc.)

• A signature from an official of the supplying firm and an effective date

The document also can be used to provide the guarantee that the packaging material comes from the establishment where the material was manufactured, as well as the corporate entity. It is important to audit these letters of guarantee on a periodic basis due to rampant consolidation in the food packaging industry—company name and ownership changes can occur overnight, invalidating the ongoing letter of guarantee. Also, if the materials utilized in the packaging structure are not Generally Recognized As Safe (GRAS) or are not currently under petition with FDA, they should not be accepted for use.

When a supplier issues a product lot to be sent to your facility by railcar, boat or truck, a bill of lading is provided. Each lading must list the material’s lot identifier, the brand name of the packaging product, and a certificate of analysis (COA) that shows that the packaging is within the agreed specifications for shelf life and critical attributes. The food manufacturer can additionally negotiate that the COA provide analytical data pertaining to specific biological, physical or chemical hazards. For instance, the processor may require a COA on packaging cleanliness as part of the purchase agreement. This is especially critical for packaging used in ready-to-eat products where packages may not receive a microbial intervention. To meet the agreement terms, the supplier will perform trace analysis via ATP bioluminescence or a total plate count on representative samples of the lot of packaging material to verify that it is clean from a microbiological aspect.

Ultimately, good vendor relations is key to effective source control. When vendors have an intimate understanding of your business and your food safety and quality assurance policies and requirements, they generally do go the extra mile. One way packaging suppliers and their food processor customers can establish a successful working relationship is to develop a mutually agreed upon definition of common defect names. For example, if the processor receives a lot of material that is perceived as nonconforming, but he can’t articulate the suspected problem to the packaging supplier, the supplier may not think there is anything wrong with the material. If this happens, gridlock occurs until the question can be resolved—and until it is, the processor’s manufacturing and customer service sector may falter.

Internal Control: Pre-Run
When the packaging material arrives on the food plant dock, the food company’s internal process control systems come into play. The first control step is to conduct a receiving audit. This involves a review of the COA and bill of lading to ensure that the correct products are delivered and that they meet the established specifications. The bill of lading for the packaging material that you are accepting into your facility should list an identifier that can be matched to the seal on the truck, railcar or boat that is entering your facility grounds. This is a critical point in your biosecurity control plan. Ideally, the inspection of the seal integrity is conducted by food plant personnel, not the truck driver or transportation company.

As soon as the truck is opened, you should inspect the actual condition of the materials. Do the materials have a pungent odor that might indicate that the load was held in unsanitary conditions? Are the containers water-damaged or torn? It is a good idea to establish and document the criteria necessary to reject a load and provide clear instructions on how to do so. Is a visual assessment enough, or should dock personnel call in supervisory staff who are trained to recognize unsanitary conditions for verification before a load is rejected? The people at the front door must be empowered to decide when a load is rejected, whether it is deemed a biosecurity threat or a housekeeping issue, such as unsanitary or damaged condition.

Once traceability has been established by the packaging material manufacturer, the food processor must maintain that traceback chain through good recordkeeping and documentation to avoid any gaps during product transfer. When the truckload of tin cans or glass containers arrives at the plant, information such as the type, volume and lot number of material delivered, the time and date received, and the condition in which the materials are received are examples of data that will need to be entered into the food company’s traceability system.

Once the materials are accepted and traceability is established, the next important process control step is to make sure that it gets transported and stored in conditions that are both sanitary and secure. Investing effort into conducting a biosecurity review on a material that comes through your door and then placing it in unlocked warehouses next to busy roads undermines your security goals. Accepting material following an intense receiving audit, only to place it in a storage facility that has a leaking roof or in an area where lots can be commingled introduces food safety risk and invalidates the packaging supplier’s hard work in establishing traceability, respectively.

Similarly, the processor needs to develop an inventory control system, such as a first in/first out (FIFO) rotation, to avoid keeping packaging materials in the warehouse beyond their shelf life. Some plants have the luxury of personnel who can routinely conduct packaging material audits to ensure that materials are stored and rotated properly. Those operations that do not have this luxury should, at minimum, institute a program of random audits for added assurance that stored packaging materials are intact, held in sanitary condition and meet functional requirements. Once the processor has generated the receiving and storage records, they need to be stored internally and reviewed in the same manner as any other critical record in your quality assurance (QA) or HACCP prerequisite program.

There are a few additional process control steps after the materials have been cleared by the QA department and are deemed ready for use. First, before the materials reaches the production line, it is important that there is a foreign material intervention step. This helps to ensure that there is little risk that foreign material will be present in the package before you fill it with good, wholesome product. Common tools used to accomplish this include inversions with deionizing air rinsers or pressure washers using a sanitary water supply that has been heated or pressurized to adequately evacuate the package. Packages are usually blown out with a sanitary air source to ensure that there isn’t any residual left on the packaging prior to filling.

Second, when conveying the packaging materials to the filling lines or to the area where you will be packaging the components, it must be done in such a manner as to preclude the materials from being adulterated or otherwise contaminated by a biological, chemical or physical hazard. For example, if you are conveying glass or other open packaging like metal cans or films, it is a good idea to transport them under a covered path (i.e., covers over lines) to keep foreign materials or overspray from cleanup operations from contaminating the packaging as it passes by.

Internal Control: In-Process
Obviously, all critical settings related to the forming or sealing criteria of the package should be documented, and provided to trained operations personnel prior to manufacturing any product destined to leave the processor’s control. As the containers hit the line at the finished packaging stage, an intermediate process inspection of the material should also occur, which includes functional testing. Processors interested in providing hermetic seal due diligence, or that want to ensure that their package is going to survive in the long haul—all the way to the consumer’s kitchen—will employ in this inspection many of the methods characterized in the FDA Bacteriological Analytical Methods (BAM), which includes testing methods for all types of packaging material designs and components.

From a safety and quality standpoint, food packaging is considered a barrier, whether it prevents gas diffusion or the entry of microoganisms through hermetic seal integrity. Functional testing of packaging ensures that the container is in fact providing that barrier to food contaminants. The methods used for testing package integrity should be robust and repeatable as characterized through gauge R&R studies. It is important that all instruments used in this intermediate inspection are calibrated and verified. Staff must be trained to properly perform the tests and to interpret the test data. In order to gain a good understanding of what is happening in the packaging process—and to prevent large failures and potential recalls from occurring due to critical package nonconformances—these tests should be trended at the line using SPC. Clearly stated AQLs need to be present for any defects rec-orded. Periodic assessment of short-term process capability (CPk) and long-term process performance (PPk) will provide the processor with additional insight into variations within the packaging process.

This documentation, which should be kept on site, needs to be linked to the day’s production run and cross-linked to the day code of the product and the packaging component. Obviously, all lots introduced to the line (via loading or splicing) should be recorded by number and unique time of use to preserve traceability. Any discoveries of non-conforming packaging, whether it be on way to the process line or during a post-process inspection, must be recorded and immediately flagged for review by competent personnel in both the QA and Operations departments.

Each manufacturing facility should have a system in place to deal with these nonconformances and to identify the quantities of product that could be affected, whether defects are critical, major or minor in nature, and what lot of packaging these represent. It is very important that this control process is systematized and reviewed regularly, since the documentation of small numbers of minor and major defects over time may, at some point, indicate that a much larger problem exists. The reporting that results from the nonconformance process will be critical during periodic reviews with packaging suppliers.

Internal Control: Post-Process
After you’ve completed the functional testing and the finished food product is sealed, post-process product sampling may be conducted. Many may view this step as a waste of resources, but most suppliers and food manufacturing facilities do not possess the process stability and highly evolved preventative maintenance systems to justify not performing a due diligence check. Just knowing that the packaged product is safe and of good quality at the time of fill does not tell you if it survived your process, or if any post-processing activities, such as loading and unloading of product by case packers, has affected your product deleteriously. For this reason, the quality control (QC) measure most prudent to employ is statistical sampling or incubation sampling of the finished product to provide assurance that the package has maintained its desirable characteristics throughout the production and internal distribution process.

The number of samples pulled will depend on many factors, including the established lot size, the production for a given day and other process-dependent factors, such as how many handling units and fillers are used, or whether historical data has given an established operational characteristics curve (OC). Many food processors look to Mil Standard 105E (now maintained as ANSI/ASQ Z1.4) for guidance on how many units to sample and when to suspend tightened inspection regimes. Typically, for shelf-stable or thermally processed foods, incubation sampling will take place a few days or weeks following production, depending on the crieria outlined in the plant’s QC procedures or corporate policies. This ensures that if bacteria has entered the package due to a lack of hermeticity, the organisims will have had sufficient time to grow and present defects upon visual inspection, whether a swollen can or a leaking package.

While you’re taking QC statistical samples, it is important to look for and document significant container damage. This is absolutely critical because if you record the kind of container damage that occurs at a particular point, SPC can be used to identify trends and sleuth out what caused that damage. For instance, if a section of guide rail protrudes into a part of the conveying line that cannot be readily seen during the day when the line is running, it may cause that section of conveyor to produce a pinch point for the packages. This unseen problem could be causing the line to randomly dent every tenth package in the process, and you will never know unless a post-processing inspection is conducted. By using a drawing that demarcates the container by zones, you can record the specific area of the container where the damage is occurring, and then apply SPC to understand whether certain zone-specific damage is above normal controlled conditions, allowing you to hone in on a root cause and take corrective action.

Another post-process control for packaging that is useful is a periodic walk-through on a set auditing frequency of the sample retention library of finished products held for shelf-life assessment. This can help you to spot problems that might occur in the field, especially with products packaged in oxygen-scavenging materials or in newly commercialized packaging. If you see discoloration or leaking packages within undistributed packages held for a short times in the sample library, the packaging will need to be reevaluated. Though these samples do not provide sample sizes necessary to draw statistically based conclusions, they are good acid tests to ensure that the product is not going to prematurely fail due to an unknown or unforeseen package design or application issue.

It also is a good practice to periodically send random samples of your packaging materials to a reputable third-party testing laboratory, and to discuss with your packaging supplier your intention to do so. The packaging supplier often can suggest labs that specialize in methods for a range of packaging tests, including gas diffusion rate testing, metrology and/or analysis of indirect additives through leaching studies.

Finally, audit the functional program areas. Audit to ensure that partial lots of unused packaging materials are recorded and inventoried because partial lots are notorious for destroying lot traceability. Ensure that packaging materials are cleared out the way during extended periods of downtime on a manufacturing line or during periods where maintenance, fabrication or cleanup is taking place. These materials represent an increased risk because materials left on the line, that have already passed your washing and other inspection systems, can readily become a source of biological, chemical and physical hazards. If there is overhead drilling or a cleanup in an area where food packaging is left on the line, that packaging can become contaminated with concrete residues, lubricants, metal swarf or cleaning chemicals.

It is also very important to have procedures in place to deal with foreign materials found in packaging or found in product that has originated from the packaging itself. Automation of X-ray, magnetic separation, machine vision and other technologies has greatly improved the plant’s ability to detect and correct physical hazards present in-processing. A post-process audit of these systems ensures that they are functioning for enhanced process control.

External Focus: Reality Check
Many external factors can adversely affect the integrity of food packaging. To mitigate these, you must understand the intended distribution path of your product. It is one thing to sell a product to a local grocer; it is another to ship it over the Rockies or overseas. The packaging itself is subjected to many forces during transport that could cause it become unfit for further distribution.

The storage and presentation of your product in outside distribution centers is another area in which the food processor does not have direct control. Are your retail or distribution channel customers maintaining agreed-upon stacking specifications at their storage facilities, for example? Are they going to stack your product six pallets high when you only planned for three? Unless you know how your customers are going to handle the product, it is difficult to design packaged products that meet their requirements.

Also, understanding how the consumer intends to handle your product is important, so that you can provide clear opening, handling and storage instructions for improved food safety at the “fork” level.

By looking at and trending records related to external factors, including data derived from consumer hot-line feedback, customer complaints and rejections and reclamation/unsaleables rates, you gain an external focus that not only shows if your process controls are working, but provides valuable data on the real-world functionality and food safety aspects of your packaging. These data are to be shared with the packaging supplier and factored into your next packaging design to improve the packaging’s attributes and to develop the necessary design, source and internal process controls needed to maintain those attributes. The external focus links these three control processes, creating a systematic loop that delivers the whole package of product safety and quality

Doug Peariso has held several key business positions during his last five years with Gerber Products Co. Among his many responsibilities has been the management of all plant systems related to finished product safety and quality for Gerber’s North American operations while acting as the Senior Quality Assurance Manager for North American Foods. Most recently he has been responsible for the operational oversight of Gerber’s new aseptic processing and packaging system. Currently on leave from Gerber, he is completing a book entitled, “Preventing Foreign Material Contamination of Foods,” which will be published by Blackwell in July. He can be reached at doug.peariso@cps4you.com.

Categories: Process Control: Packaging, Processing Technologies