Stability or Shelf-Life is defined as the extent to which a product retains, within specified limits, and throughout its period of storage and use, ie., Shelf-Life, the same properties and characteristics that is possessed at the time of its packaging.
The four types of stability generally recognized for most products are as follows:
- Chemical: The product retains it chemical integrity and potency, within specified limits.
- Physical: The original physical properties, including appearance, palatability, odor, and wholesomeness are retained.
- Microbiological: Resistance to microbial growth and product safety is retained according to specified requirements overall bacterial growth is maintained within acceptable levels.
The shelf-life testing protocol may be customized for each type of food group submitted for testing and will pertain to the parameters outlined above. Appropriate tests for determination of identity, wholesomeness and quality of a given product will be outlined prior to the initiation of the stability study.
- Microbiological Analysis
- High Pressure Liquid Chromatography (HPLC) Analysis
- Chemical Analysis
- Water Activity (aw)
Shelf Life Testing
Shelf life testing is performed to test the bacterial integrity of a finished product. Demonstrating the absence of pathogenic bacteria in the product is the safest way of avoiding consumer cases regarding food borne illness. The finished report is an excellent sales tool as it indicates that the product is shelf stable and free of pathogenic bacteria.
A projected shelf life should include a reasonable time for production, distribution, sale and consumption. Also the shelf life should be establish beyond the actual expiry date of the product to insure that an out of date product is safe beyond the expiry date marked. The laboratory will assist you in setting up a shelf life study. Most importantly if there is a problem the study is halted and the problem is stated and addressed prior to repeating the study, this as part of product development.
Accelerated Shelf Life Study:
The FDA has established the guidelines for Accelerated Stability studies primarily in pharmaceutical products which would apply to the Accelerated Shelf Life studies in food products. Three (3) months at elevated temperature 35 degrees Centigrade is equivalent to one (1) year of product shelf life monitoring the Microbiological profile of the product (Total Plate Count, Coliforms, Fecal Coliforms, E. coli, Staphylococcus aureus and Mold and Yeast). If the product is stable there should not be an increase in Microbial content as the product is incubated. Salmonella and Listeria are tested along with all of the tests listed at the Initial time point, one month, two month and three month time points. Two years of Accelerated Shelf Life study would be six (6) months of incubation with additional testing time points.
Room Temperature Shelf Life Study:
Ambient temperature studies are carried out at 25 degrees Centigrade and are conducted in real time. The testing is carried out in the same manner for each time point. Products which are not able to be heated or where mold and yeast may be a problem, such as baked goods would be tested under these conditions.
Refrigerated Shelf Life Study:
An initial sample is tested for the following Microbiological Series when the samples are received. After being tested, the sample is returned to the Chemistry laboratory and the pH is measured. The remaining three samples are placed under refrigeration at 33 Degrees Fahrenheit until the time they are to be tested. The time points for the testing in a refrigerated study are determined by the nature of the product. The following tests will be performed according to the AOAC methods cited below.
Total Aerobic Count (Aerobic Plate Count): FDA Bacteriological Analytical Manual (BAM), 8th Edition, Chapter 3, 1998.
Coliform Count & E.coli: AOAC, 17th Edition Chapter 17, Section 966.23 – 966.24. FDA Bacteriological Analytical Manual (BAM), 8th Edition, Chapter 4, 1998.
Staphylococcus aureus: AOAC, 17th Edition Chapter 17, Section 975.55 & 987.09. FDA Bacteriological Analytical Manual (BAM), 8th Edition, Chapter 12, 1998
Total Molds and Yeast (Aerobic Plate Count) FDA Bacteriological Analytical Manual (BAM), 8th Edition, Chapter 18, 1998.
*PCR Salmonella spp and Cultural Confirmation: SOP 1.1, AOAC – RI 051303
*PCR Listeria spp. and Cultural Confirmation: SOP 2.2, 2.2, AOAC – RI 071304
*PCR Listeria monocytogenes and Cultural Confirmation: SOP 2.1, 2.2, AOAC – RI 061302
*Initial Time Point
Time Points to be examined (example)
A projected Shelf Life should include a reasonable time for production, Distribution, Sale and Consumption. Also, the Shelf Life should be established beyond the actual expiry date to insure that an out of date product is safe beyond the expiry date marked. A projected expiry date of fourteen (14) days should have a final time point at 18 to 21 days. The data will then provide a margin of documented Product Safety. Time Points would be Initial, Day 7, Day 14 and Day 21. Each product will be evaluated prior to running the study to determine the time points to be tested.
Total Plate Count – All of the Aerobic Bacteria present. This test gives a general view as to the Microbiological condition of the sample.
Coliforms – Coliform bacteria are indications of general sanitation status of the product.
E. coli – E. coli is a human fecal marker and should not be present. May represent a pathogen.
Staph. aureus – Staphylococcus aureus is a common cause of food poisoning derived from product handling.
Mold /Yeast – Can be spoilage organisms and can produce aflatoxins. Some individuals have allergic reactions to both mold and yeast.
Upon the completion of the study a report is issued containing the four sets of test results indicating the testing time points. The results will declare the stability of the product and the report will contain the following statement:
Based upon the Microbiological results of the sample listed above and insofar as the analyses performed were able to assay for the presence or absence of specific pathogens, the product represented by the sample analyzed would appear to be wholesome and fit for human consumption for a projected shelf life of (time indicated)
Samples needed: 5 individual containers
Turn Around Time: Accelerated three months (1 year) (refrigerated – real time)
Cost Shelf Life Testing: $550.00 – Please send payment with samples
Extra Timepoints: $95 per timepoint
*Requires five (5) finished product samples to be submitted per product per study.
*Contact Laboratory for Chain of Custody to be submitted with samples.
Kappa Laboratories has been Inspected and previously Recognized by the U.S. Department of Agriculture (USDA Microbiology-#0093, Chemistry-#1282); ISO 17025 Certified Listeria species, Listeria monocytogenes, Salmonella species; Registered with the U.S. Food and Drug Administration (FDA-#1039390) and is an FDA Accepted Laboratory for Import Testing. Kappa Laboratories is currently a Contract Laboratory to the U.S. Centers for Disease Control (CDC), Atlanta, Georgia; Vessel Sanitation Program. Contract Laboratory, U.S. Coast Guard for Alaskan Vessel Discharge Program. ISO/IEC 17025 Accredited: Salmonella spp., Listeria spp. And Listeria monocytogenes.
To get started with Kappa Laboratories Testing Services, send an e-mail to the laboratory (firstname.lastname@example.org) with the following details:
- Description of the sample to be analyzed.
- Description of matrix to be analyzed.
- Determination of methods to be employed.
- Number of samples and number of analytes to be determined.