Shelf life
Shelf life is the length of time that a commodity may be stored without becoming unfit for use, consumption, or sale.[1] In other words, it might refer to whether a commodity should no longer be on a pantry shelf (unfit for use), or no longer on a supermarket shelf (unfit for sale, but not yet unfit for use). It applies to cosmetics, foods and beverages, medical devices, medicines, explosives, pharmaceutical drugs,[2] chemicals, tyres, batteries, and many other perishable items. In some regions, an advisory best before, mandatory use by or freshness date is required on packaged perishable foods. The concept of expiration date is related but legally distinct in some jurisdictions.[3]
Background
Shelf life is the recommended maximum time for which products or fresh (harvested) produce can be stored, during which the defined quality of a specified proportion of the goods remains acceptable under expected (or specified) conditions of distribution, storage and display.[4]
According to the United States Department of Agriculture (USDA), "canned foods are safe indefinitely as long as they are not exposed to freezing temperatures, or temperatures above 90 °F (32.2 °C)". If the cans look okay, they are safe to use. Discard cans that are dented, rusted, or swollen. High-acid canned foods (tomatoes, fruits) will keep their best quality for 12 to 18 months; low-acid canned foods (meats, vegetables) for 2 to 5 years.[5]
"Sell by date" is a less ambiguous term for what is often referred to as an "expiration date". Most food is still edible after the expiration date.
Shelf life depends on the degradation mechanism of the specific product. Most can be influenced by several factors: exposure to
For some foods, health issues are important in determining shelf life. Bacterial contaminants are ubiquitous, and foods left unused too long will often be contaminated by substantial amounts of bacterial colonies and become dangerous to eat, leading to
Pharmaceuticals
The expiration date of pharmaceuticals specifies the date the manufacturer guarantees the full potency and safety of a drug. Most medications continue to be effective and safe for a time after the expiration date. A rare exception is a case of renal tubular acidosis purportedly caused by expired tetracycline.[9] A study conducted by the U.S. Food and Drug Administration covered over 100 drugs, prescription and over-the-counter. The study showed that about 90% of them were safe and effective as long as 15 years past their expiration dates. Joel Davis, a former FDA expiration-date compliance chief, said that with a handful of exceptions - notably nitroglycerin, insulin and some liquid antibiotics - most expired drugs are probably effective.[10]
Shelf life is not significantly studied during drug development[
Packaging factors
Preservatives and antioxidants may be incorporated into some food and drug products to extend their shelf life. Some companies use induction sealing and vacuum/oxygen-barrier pouches to assist in the extension of the shelf life of their products where oxygen causes the loss.
The DoD Shelf-Life Program defines shelf-life as
The total period of time beginning with the date of manufacture, date of cure (for elastomeric and rubber products only), date of assembly, or date of pack (subsistence only), and terminated by the date by which an item must be used (expiration date) or subjected to inspection, test, restoration, or disposal action; or after inspection/laboratory test/restorative action that an item may remain in the combined wholesale (including manufacture's) and retail storage systems and still be suitable for issue or use by the end user. Shelf-life is not to be confused with service-life (defined as, A general term used to quantify the average or standard life expectancy of an item or equipment while in use. When a shelf-life item is unpacked and introduced to mission requirements, installed into intended application, or merely left in storage, placed in pre-expended bins, or held as bench stock, shelf-life management stops and service life begins.)[16]
Shelf life is often specified in conjunction with a specific product, package, and distribution system. For example, an
Temperature control
Nearly all chemical reactions can occur at normal temperatures (although different reactions proceed at different rates). However most reactions are accelerated by high temperatures, and the degradation of foods and pharmaceuticals is no exception. The same applies to the breakdown of many chemical explosives into more unstable compounds.
The often quoted rule of thumb is that chemical reactions double their rate for each temperature increase of 10 °C (18 °F) because activation energy barriers are more easily surmounted at higher temperatures. However, as with many rules of thumb, there are many caveats and exceptions. The rule works best for reactions with activation energy values around 50 kJ/mole; many of these are important at the usual temperatures we encounter. It is often applied in shelf life estimation, sometimes wrongly. There is a widespread impression, for instance in industry, that "triple time" can be simulated in practice by increasing the temperature by 15 °C (27 °F), e.g., storing a product for one month at 35 °C (95 °F) simulates three months at 20 °C (68 °F). This is mathematically incorrect (if the rule was precisely accurate the required temperature increase would be about 15.8 °C (28.4 °F)), and in any case the rule is only a rough approximation and cannot always be relied on. Chemists often use the more comprehensive Arrhenius equation for better estimations.
The same is true, up to a point, of the chemical reactions of living things. They are usually catalyzed by
Just as temperature increases speed up reactions, temperature decreases reduce them. Therefore, to make explosives stable for longer periods, or to keep rubber bands springy, or to force bacteria to slow down their growth, they can be cooled. That is why shelf life is generally extended by temperature control: (refrigeration, insulated shipping containers, controlled cold chain, etc.) and why some medicines and foods must be refrigerated. Since such storing of such goods is temporal in nature and shelf life is dependent on the temperature controlled environment, they are also referred to as cargo even when in special storage to emphasize the inherent time-temperature sensitivity matrix.
Temperature data loggers and time temperature indicators can record the temperature history of a shipment to help estimate their remaining shelf life.[18]
According to the
Packaging
Passive barrier packaging can often help control or extend shelf life by blocking the transmission of deleterious substances, like moisture or oxygen, across the barrier.
Related concepts
The concept of shelf life applies to other products besides food and drugs. Gasoline has a shelf life, although it is not normally necessary to display a sell-by date. Exceeding this time-frame will introduce harmful varnishes[clarification needed], etc. into equipment designed to operate with these products, i.e. a gasoline lawn mower that has not been properly winterized[clarification needed] could incur damage that will prevent use in the spring, and require expensive servicing to the carburetor.
Some glues and adhesives also have a limited storage life, and will stop working in a reliable and usable manner if their safe shelf life is exceeded.
Rather different is the use of a time limit for the use of items like vouchers, gift certificates and pre-paid phone cards, so that after the displayed date the voucher etc. will no longer be valid. Bell Mobility and its parent company, BCE Inc. have been served with notice of a $100-million class-action lawsuit alleging that expiry dates on its pre-paid wireless services are illegal.[20]
See also
- Accelerated aging
- Cold chain
- Digital permanence
- Expiration date
- Failure rate
- Food waste
- Inventory turnover
- Modified atmosphere
- Moisture sorption isotherm
- Moisture vapor transmission rate
- Packaging and labelling
- Permeation
- Planned obsolescence
- Redox
- Shelf stable
- Yellow sticker
References
- ^ Oxford English Dictionary, 2nd ed.
- ^ Forcinio, Hallie (2 October 2018). "Protecting Solid-Dose Shelf Life". Pharmaceutical Technology. Vol. 42, no. 10. UBM. Retrieved 8 November 2018.
- ^ Affairs, Government of Canada,Canadian Food Inspection Agency,Public (21 March 2012). "Date Labelling on Pre-packaged Foods". www.inspection.gc.ca. Retrieved 1 September 2017.
{{cite web}}
: CS1 maint: multiple names: authors list (link) - ISBN 978-0-8031-1417-3. ASTM STP 1113-EB.
- ^ a b "Food_Product_Dating". Retrieved 2015-04-24.
- ^ See "Expiration dates". Consumer Affairs. Retrieved 11 November 2011.
- S2CID 136702424.
- ^ "Can You Drink Milk Past Its Sell-by Date?". Dairy Council of California. Retrieved 30 May 2017.
- PMID 15266231.
- ^ Cohen, Laurie P. (2000-03-28). "Many Medicines Prove Potent for Years Past Their Expiration Dates". Wall Street Journal. Vol. 235, no. 62. pp. A1 (cover story).
- ^ "US Army Medical Materiel Agency (USAMMA)". Usamma.army.mil. 2013-11-20. Archived from the original on 2015-03-18. Retrieved 2014-02-08.
- ^ "Maximizing State and Local Medical Countermeasure Stockpile Investments Through the Shelf-Life Extension Program". Upmc-biosecurity.org. Archived from the original on 2013-01-18. Retrieved 2014-02-08.
- ^ "Essentialdrugs.org". Essentialdrugs.org. Archived from the original on 2013-12-11. Retrieved 2014-02-08.
- ^ "Stockpiled Antivirals at or Nearing Expiration". Fda.gov. Retrieved 2014-02-08.
- ^ http://www.usamma.army.mil/assets/docs/dlar.pdf Archived 2017-12-09 at the Wayback Machine [bare URL PDF]
- ^ "The DoD Shelf-Life Program - Shelf-Life Management Manual - Definitions". Archived from the original on 2007-01-01.
- United States Army Soldier Systems Center. Archived from the originalon October 26, 2018. Retrieved September 28, 2010.
- ^ Meyers, T (June 2007). "RFID Shelf-life Monitoring Helps Resolve Disputes". RFID Journal.
- ^ a b Forcinio, Hallie (2 October 2018). "Protecting Solid-Dose Shelf Life". Pharmaceutical Technology. Vol. 42, no. 10. UBM. Retrieved 8 November 2018.
- ^ [1] Archived May 16, 2012, at the Wayback Machine
Further reading
- "New Guidelines Seek to Provide Clarity on Food Expiration Dates". All Things Considered. U.S.: NPR. 17 February 2017. Includes a list of the many terms used in the United States food industry.
- Anonymous, "Cold Chain Management", 2003, 2006
- Anonymous, Protecting Perishable Foods During Transport by Truck Archived 2014-05-16 at the Wayback Machine, USDA Handbook 669, 1995
- Kilcast, D., Subramamiam, P., Food and Beverage Stability and Shelf Life, Woodhead Publishing, 2011, ISBN 978-1-84569-701-3
- Labuza, T. P., Szybist, L., Open dating of Foods, Food and Nutrition Press, 2001; other edition: Wiley-Blackwell, 2004, ISBN 0-917678-53-2
- Man, C. M., Jones. A. A., Shelf-Life Evaluation of Foods, ISBN 0-8342-1782-1
- Robertson, G.L., Food Packaging and Shelf Life: A Practical Guide, CRC Press, 2010, ISBN 978-1-4200-7844-2
- Steele, R., Understanding and Measuring the Shelf-Life of Food, Woodhead Publishing, 2004, ISBN 1-85573-732-9
- Weenen, H., Cadwallader, K., Freshness and Shelf Life of Foods, ACS, 2002, ISBN 0-8412-3801-4