What is a process review of a commercial food product?
A process review of a commercial food product is a complete evaluation of how a food product is made, including all the steps of preparation, ingredients and packaging.
Commercial canning of food has evolved from the closed kettle system developed by A.K. Shriver in 1874—the first retort system, similar to a pressure cooker—to aseptic processing—the latest method, in which the food is sterilized, then packaged under sterile conditions. Boiling water baths have been used for centuries but do not provide adequate heating to prevent microbial spoilage nor control Clostridium botulinum in low-acid food. The primary concern associated with canned food is that these foods be considered safe to eat without further cooking by the final consumer. Therefore, it is critical that these foods be processed with the greatest vigilance with regard to food safety to control toxins from Clostridium botulinum.
When is a process review of a commercial food product necessary?
A process review is required to assure the U.S. Food and Drug Administration (FDA) that a food product sold commercially sterile will not harm the final consumer.
Low acid and acidified foods that are shelf-stable and sold without refrigeration require evaluation by a process (or processing) authority. As defined in the Code of Federal Regulations (21 CFR113.83 and 113.89), “A processing authority is a person who has expert knowledge of thermal processing requirements for low-acid foods packaged in hermetically sealed containers, or has expert knowledge in the acidification and processing of acidified foods.”
Regardless of the method used to can foods, the processor must ensure that the finished product is a safe food product. It is the processor’s responsibility to determine the status of their products under the regulations 21 CFR 113-114. A processor should first request the assistance of a process authority. A process authority is available at New Mexico State University and at other state universities. In the case of novel products, the processor may need to contact the Food and Drug Administration (FDA) directly as to the status of their product.
How does a process authority evaluate a commercial food product?
A process authority evaluates the thermal process for food and must have expert knowledge of thermal process, hermetically sealed containers, and food microbiology, and have facilities to determine a safe process or process schedule for each product. A process schedule is designed by a process authority to deliver a “commercially sterile” (FDA) or “shelf-stable” (USDA) food product. The process schedule describes acidification, preservatives, packaging and the application of heat or cooking used to eliminate microorganisms in the product handled under non-refrigerated conditions. The microbial quality of the final food product is determined by collecting a sample and performing bacterial counts such as aerobic plate count, E. coli, coliforms, yeast and mold counts. The stability (change in water activity or acidity) of the food once canned is another measure of product safety.
The cooking step in making a food product is called a thermal process. A thermal process is established by understanding the food microbiology and processing method for the specific food that is canned. Food spoilage microorganisms are present throughout the environment, packaging containers and ingredients. High temperature kills microorganisms present in food, and the hermitically sealed container prevents re-contamination.
The thermal process is determined by:
- Food product
- Container dimensions
- Time and temperature
- Growth and survival of thermal-resistant microorganisms
There are two factors used to evaluate the safety of a thermal process. These are the heat resistance of microorganisms—or the heat needed to destroy the microorganism in the food—and the heating rates of specific foods. Thermal processes are specific to food formulation, preparation, container and thermal method used. The thermal resistance of the microorganism depends on the growth characteristic of the microorganism and on the nature of the food, that is, the acidity of the food or if it is whole, chopped or pureed. A dense food such as meat will heat more slowly than, say, asparagus. Similarly, a mashed vegetable will heat more slowly than whole vegetables in a brine or broth. Food product heating data are collected by placing a temperature sensor in the product at the slowest heating (coldest) region. Heating rate for the retort process depends on type of product and container size and shape. Once the thermal process is determined, the schedule process can be filled out on FDA forms 2541 and 2541a (Figures 1 and 2) and must be followed precisely as indicated by the process authority.
Figure 1. FDA form 2541, facility registration form
Figure 2. FDA form 2541, a scheduled process
How are foods made to be commercially sterile?
Commercially sterile products can be made by several different methods. The most common processes used are retorting—processing at high heat and pressure—and acidification of low acid foods, which also includes aseptic processing. Each process has specific instrumentation and steps that must be followed to produce a safe product. The following information is presented as a brief introduction to each process:
Low-acid foods such as meat or vegetables must be thermally processed in a retort. Retort operating procedures are designed to provide uniform temperature distribution under pressure using a heating media (usually steam) throughout the retort. Processing canned food under pressure allows the temperature to rise to 250°F, which will destroy the spores of Clostridium botulinum. A retort thermal process is very complex and requires special instruments to verify the safety of the thermal process. Therefore, most small food processors use an acidified method followed by pasteurization, known as hot fill and hold.
The hot fill and hold process can be used to process foods that are acid or acidified. All ingredients are thermally processed in a steam kettle to a temperature of at least 180°F, then transferred to clean containers, sealed and held for a pre-determined time. Reaching a temperature of 180°F is critical to push out any air remaining within the container; as it cools, a vacuum is formed, resulting in a hermetically sealed container.
Acid or acidified foods must have an acidity of less than 4.6 pH at equilibrium (the point at which pH will no longer change). This acidity level will control Clostridium botulinum, which is the microorganism of concern for canned food. The acidity equilibrium point may be reached immediately, or it may take several days after processing for it to be reached. The product must be stored under refrigeration until the equilibrium point is reached. Acidified food can also be thermally processed in a heat exchanger and retort. Regardless of the thermal method, the thermal treatment must be adequate to control spoilage organisms.
Aseptic Processing and Packaging
In an aseptic system the product and package are sterilized in separate systems, then combined in a sterile environment for filling and sealing. The terms aseptic, sterile, and commercially sterile are used interchangeably but imply that the product is clear of microorganisms. Aseptic systems must be capable of sterilizing the equipment used to produce sterile product and sterile packages. Additionally, the environment area of production and filling must be kept sterile. All systems must be monitored and recorded to ensure proper handling of the finished product.
Food that is processed through an aseptic system must be fluid so that a pump can transport the product, and the pump must have a controllable flow rate so that all food particles receive an adequate thermal process. Pumps are set at a fixed rate so that there are no changes in speed or thermal process. The aseptic system used must have safeguards to heat and recycle product, then hold product for a required time and temperature. Product can be heated directly by steam injection or steam infusion. Indirect product heating can be done by heat exchangers. Aseptic product must be cooled quickly; it is then moved to a filling and sealing unit. Aseptic packaging is sterilized by ultraviolet radiation or in a peroxide bath prior to being filled with sterilized product.
Once sealed, the product is a hermetic shelf-stable product that can be shipped and stored like any other canned food product. The main advantage of this system is the variety of packaging types that can be used.
How do I submit a commercial food product for process review to a process authority?
Make a final test batch packaged in final packaging, not prototype. Collect information such as weight and acidity of each ingredient. Fill out form (Table 1) used by process authority as completely as possible with the following information (see example in Table 2):
- The final product name, packaging and distribution method (how does it get to market?)
- The recipe, with ingredients listed by weight (not cups or teaspoons) and pH— novel ingredients may require information from the manufacturer
- Acidifier such as vinegar or lemon juice and preservative (if used)
- Changes in product weight during processing
- Process controls such as time, temperature, pH, water activity
- Processing steps used to make product
- Consumer preparation used before eating
Additionally, two samples of the final product should be sent to a laboratory for evaluation of microbial counts, pH and water activity. A report should be sent to the process authority to assist with evaluation of the food product.
Table 1. Food Tech Nutrition and Process Review Sheet
Table 2. Example of completed Food Tech Nutrition and Process Review Sheet
What does the process review tell me about my product?
The process review letter (Figure 3) issued to the processor should contain information on the product classification, regulations that apply to product, and recommended processing steps. The letter may also contain information interpreting microbial and chemical test results.
Figure 3. Process Review Letter
Checklist for a process review of a commercial food:
- Contact food processing expert, process authority (NMSU Extension Food Technology).
- Contact appropriate regulatory agency (U.S. FDA, State Department of Health).
- Apply for city, state, federal permits (as needed).
- Process test batch of final product.
- Record information from test batch on forms (Table 1).
- Submit samples to laboratory for evaluation of microbial counts, pH and water activity.
- Submit information to process authority.
- Receive process review letter (copy and store) (Figure 3).
- Fill out FDA forms 2541, 2541a for acid and acidified foods (Figures 1 and 2).
- Submit copy of process review letter and FDA 2541 and 2541a to Low-Acid Canned Foods (LACF) at the Center for Food Safety and Nutrition (FDA). http://www.fda.gov/Food/FoodSafety/Product-SpecificInformation/AcidifiedLow-AcidCannedFoods/default.htm
- Submit paperwork to local regulatory agency.
- Submit final product label (21 CFR 101.1- 101.9) to local regulatory agency.
- Product is now legal for market.
Foods, including fermented foods, that have a natural pH of 4.6 or below. Natural pH means the pH prior to processing. However, if during processing the pH rises above 4.6 (through washing, lye peeling, etc.) and an acid or acid food is added to reduce the pH to 4.6 or below, that product would be considered an acidified food.
Low-acid foods to which acid(s) or acid food(s) are added and which have a water activity (aw) greater than 0.85 and a finished equilibrium pH of 4.6 or below.
Commercially Sterile Product
Food in a hermitically sealed package that will not allow any viable microorganisms to grow and in which microorganisms cannot be detected by usual bacterial culturing methods.
A spore-forming bacteria that is capable of forming a toxin under anaerobic conditions. The toxin is extremely deadly even in small doses. The toxin is destroyed by heat; therefore it is recommended to bring home-canned foods to a roiling boil before consumption.
The condition achieved when the solid and liquid parts of the product have the same pH. When an acid such as lemon juice is added to whole peppers, equilibrium might not be reached for several hours or several days. The product may need to be refrigerated until a pH of 4.6 is reached. The pH can be determined immediately after processing by blending the entire contents of the finished product container and taking the pH or blending the solid particles and acid brine in the proportion present in the finished product and taking the pH.
These foods may be called pickles or pickled food. In addition, the following are excluded from regulation 21 CFR 114: carbonated beverages, jams, jellies, preserves, acid foods that contain small amounts of low-acid food(s) and have a resultant finished equilibrium pH that does not significantly differ from that of the predominant acid or acid food (this includes such foods as standardized and non-standardized food dressings and condiment sauces), and foods that are stored, distributed, and retailed under refrigeration. Jams, jellies, and preserves covered by the standard of identity (21 CFR 150) are exempt foods if the water activity is 0.85 or less and the pH is 4.6 or less.
FDA form 2541 and 2541a
Forms (Figures 1 and 2) used to register food processing facility and process schedule for low-acid or acidified foods. See webpage for filing instructions. http://www.fda.gov/Food/FoodSafety/Product-SpecificInformation/AcidifiedLow-AcidCannedFoods/EstablishmentRegistrationThermalProcessFiling/Instructions/ucm2007436.htm
Low-acid foods subjected to the action of certain microorganisms which produce acid during their growth and reduce the pH of the food to 4.6 or below. They may be partially desalted, processed, or preserved in the original salt brine, in new salt brine, or in a vinegar solution with other ingredients. Foods partially fermented require addition of acid to reduce the pH to 4.6 or less.
A package that is under anaerobic conditions, that is, lacking the oxygen necessary for the growth of organisms that contaminate food.
The product produced during a period indicated by a specific code.
Any foods, other than alcoholic beverages, with a finished equilibrium pH greater than 4.6 and a water activity (aw) greater than 0.85. Tomatoes and tomato products having a finished equilibrium pH less than 4.7 are not classified as low-acid foods.
A process used to manufacture a food that will not permit the growth of microorganisms having public health significance. It includes control of pH and other critical factors equivalent to the process established by a competent processing authority. The process that is filed on Form FDA 2541a is considered to be the scheduled process. The critical factors necessary to achieve and maintain a safe product are listed on the process filing form. They shall be controlled, and records of the results of tests or determinations kept.
Water Activity (aw)
A measure of the free moisture in a product, which is a measure of relative humidity within the product. Any food that always has 0.85 water activity or less is excluded from coverage under 21 CFR 113-114.
Department of Health and Human Services, U.S. FDA. 21 CFR 101.1-101.9 code of federal regulation: labeling of food products. Available at: http://www.access.gpo.gov/nara/cfr/waisidx_06/21cfr101_06.html
Department of Health and Human Services, U.S. FDA. 21 CFR 113 code of federal regulation: canning of low acid foods. Available at: http://www.access.gpo.gov/nara/cfr/waisidx_02/21cfr113_02.html
Department of Health and Human Services, U.S. FDA. 21 CFR 114 code of federal regulation: canning of acidified foods. Available at: http://www.access.gpo.gov/nara/cfr/waisidx_02/21cfr114_02.html
Austin, Gavin. Canned foods: Principles of Thermal Process Control, acidification and container closure evaluation, 6th edition. (1995). Washington, DC: Food Processors Institute.
U.S. FDA Office of Regulatory Affairs. Guide to Inspections of Acidified Food Manufacturers. Accessed July, 2007 at: http://www.fda.gov/ora/Inspect_ref/igs/acidfgde.htm.
Jay, J.M. (1998). “Food poisoning caused by gram positive spore-forming bacteria” in Modern Food Microbiology, (5th Edition, pgs. 457-469). NYC: Aspen Publishers.
Note on critical factor monitoring
Regardless of the processing method used to produce hermitically sealed product there are critical factors that must be monitored for each batch of product made. In most cases acidity, temperature and water activity are critical factors to ensure food safety. These factors must be measured using a device or instrument that is accurate and that can be calibrated or verified when used. Additionally, these factors must be monitored for each batch processed. A critical factor such as acidity must be measured with a pH meter that has been calibrated with buffers pH 4 and 7; temperature is measured with a calibrated thermometer; and, if necessary, water activity is measured with a water activity meter. These instruments are available through various suppliers that can be found on the Internet.
To find more resources for your business, home, or family, visit the College of Agricultural, Consumer and Environmental Sciences on the World Wide Web at aces.nmsu.edu.
Contents of publications may be freely reproduced for educational purposes. All other rights reserved. For permission to use publications for other purposes, contact email@example.com or the authors listed on the publication.
New Mexico State University is an equal opportunity/affirmative action employer and educator. NMSU and the U.S. Department of Agriculture cooperating.
Printed and electronicaly distributed December 2007, Las Cruces, NM.