Shelf life

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This pack of diced pork says 'Display until' 7 May and 'Use by' 8 May. Expiration.jpg
This pack of diced pork says 'Display until' 7 May and 'Use by' 8 May.

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]

Contents

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. [6] A product that has passed its shelf life might still be safe, but quality is no longer guaranteed. In most food stores, waste is minimized by using stock rotation, which involves moving products with the earliest sell by date from the warehouse to the sales area, and then to the front of the shelf, so that most shoppers will pick them up first and thus they are likely to be sold before the end of their shelf life. Some stores can be fined for selling out of date products; most if not all would have to mark such products down as wasted, resulting in a financial loss.

Shelf life depends on the degradation mechanism of the specific product. Most can be influenced by several factors: exposure to light, heat, moisture, transmission of gases, mechanical stresses, and contamination by things such as micro-organisms. Product quality is often mathematically modelled around a parameter (concentration of a chemical compound, a microbiological index, or moisture content). [7]

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 food poisoning. However, shelf life alone is not an accurate indicator of how long the food can safely be stored. For example, pasteurized milk can remain fresh for five days after its sell-by date if it is refrigerated properly. However, improper storage of milk may result in bacterial contamination or spoilage before the expiration date. [8]

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[ dubious – discuss ], and drug manufacturers have economic and liability incentives to specify shorter shelf lives so that consumers are encouraged to discard and repurchase products. One major exception is the Shelf Life Extension Program (SLEP) of the U.S. Department of Defense (DoD), which commissioned a major study of drug efficacy from the FDA starting in the mid-1980s. One criticism is that the U.S. Food and Drug Administration (FDA) refused to issue guidelines based on SLEP research for normal marketing of pharmaceuticals even though the FDA performed the study. The SLEP and FDA signed a memorandum that scientific data could not be shared with the public, public health departments, other government agencies, and drug manufacturers. [11] State and local programs are not permitted to participate. [12] The failure to share data has caused foreign governments to refuse donations of expired medications. [13] One exception occurred during the 2010 Swine Flu Epidemic when the FDA authorized expired Tamiflu based on SLEP Data. [14] The SLEP discovered that drugs such as Cipro remained effective nine years after their shelf life, and, as a cost-saving measure, the US military routinely uses a wide range of SLEP tested products past their official shelf life if drugs have been stored properly. [15]

Package testing: heat sealing film for evaluation of shelf life of lettuce Heat Sealing Film for Permeability Test.jpg
Package testing: heat sealing film for evaluation of shelf life of lettuce

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 MRE field ration is designed to have a shelf life of three years at 80 °F (27 °C) and six months at 100 °F (38 °C). [17]

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. Nitroglycerine is notorious. Old explosives are thus more dangerous (i.e. liable to be triggered to explode by very small disturbances, even trivial jiggling) than more recently manufactured explosives. Rubber products also degrade as sulphur bonds induced during vulcanization revert; this is why old rubber bands and other rubber products soften and get crispy, and lose their elasticity as they age.

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 enzymes which change reaction rates, but with no variation in catalytic action, the rule of thumb is still mostly applicable. In the case of bacteria and fungi, the reactions needed to feed and reproduce speed up at higher temperatures, up to the point that the proteins and other compounds in their cells themselves begin to break down, or denature, so quickly that they cannot be replaced. This is why high temperatures kill bacteria and other micro-organisms: 'tissue' breakdown reactions reach such rates that they cannot be compensated for and the cell dies. On the other hand, 'elevated' temperatures short of these result in increased growth and reproduction; if the organism is harmful, perhaps to dangerous levels.

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 USDA, "foods kept frozen continuously are safe indefinitely". [5]

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. [19] Active packaging, on the other hand, employs the use of substances that scavenge, capture, or otherwise render harmless deleterious substances. [19] When moisture content is a mechanism for product degradation, packaging with a low moisture vapor transmission rate and the use of desiccants help keep the moisture in the package within acceptable limits. When oxidation is the primary concern, packaging with a low oxygen transmission rate and the use of oxygen absorbers can help extend the shelf life. Produce and other products with respiration often require packaging with controlled barrier properties. The use of a modified atmosphere in the package can extend the shelf life for some products.

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

Related Research Articles

<span class="mw-page-title-main">Desiccant</span> Substance used to induce or sustain dryness

A desiccant is a hygroscopic substance that is used to induce or sustain a state of dryness (desiccation) in its vicinity; it is the opposite of a humectant. Commonly encountered pre-packaged desiccants are solids that absorb water. Desiccants for specialized purposes may be in forms other than solid, and may work through other principles, such as chemical bonding of water molecules. They are commonly encountered in foods to retain crispness. Industrially, desiccants are widely used to control the level of water in gas streams.

<span class="mw-page-title-main">Sterilization (microbiology)</span> Process that eliminates all biological agents on an object or in a volume

Sterilization refers to any process that removes, kills, or deactivates all forms of life and other biological agents present in or on a specific surface, object, or fluid. Sterilization can be achieved through various means, including heat, chemicals, irradiation, high pressure, and filtration. Sterilization is distinct from disinfection, sanitization, and pasteurization, in that those methods reduce rather than eliminate all forms of life and biological agents present. After sterilization, an object is referred to as being sterile or aseptic.

<span class="mw-page-title-main">Freeze drying</span> Low temperature dehydration process

Freeze drying, also known as lyophilization or cryodesiccation, is a low temperature dehydration process that involves freezing the product and lowering pressure, thereby removing the ice by sublimation. This is in contrast to dehydration by most conventional methods that evaporate water using heat.

<span class="mw-page-title-main">Oxygen scavenger</span> Substance able to chemically absorb oxygen in the surrounding air

Oxygen scavengers or oxygen absorbers are added to enclosed packaging to help remove or decrease the level of oxygen in the package. They are used to help maintain product safety and extend shelf life. There are many types of oxygen absorbers available to cover a wide array of applications.

<span class="mw-page-title-main">Modified atmosphere</span>

Modified atmosphere packaging (MAP) is the practice of modifying the composition of the internal atmosphere of a package in order to improve the shelf life. The need for this technology for food arises from the short shelf life of food products such as meat, fish, poultry, and dairy in the presence of oxygen. In food, oxygen is readily available for lipid oxidation reactions. Oxygen also helps maintain high respiration rates of fresh produce, which contribute to shortened shelf life. From a microbiological aspect, oxygen encourages the growth of aerobic spoilage microorganisms. Therefore, the reduction of oxygen and its replacement with other gases can reduce or delay oxidation reactions and microbiological spoilage. Oxygen scavengers may also be used to reduce browning due to lipid oxidation by halting the auto-oxidative chemical process. Besides, MAP changes the gaseous atmosphere by incorporating different compositions of gases.

<span class="mw-page-title-main">Cold chain</span> Low-temperature supply chain

Cold chain is a set of rules and procedures that ensure the systematic coordination of activities for ensuring temperature-control of goods while in storage and transit. The objective of a cold chain is to preserve the integrity and quality of goods such as pharmaceutical products or perishable good from production to consumption. Cold chain management earned its name as a "chain" because it involves linking a set of storage locations and special transport equipment, required for ensuring that temperature conditions for goods are met, while they are in storage or in transit from production to consumption, akin to the interconnected links of a physical chain.

Moisture vapor transmission rate (MVTR), also water vapor transmission rate (WVTR), is a measure of the passage of water vapor through a substance. It is a measure of the permeability for vapor barriers.

<span class="mw-page-title-main">Blister pack</span> Type of packaging

A blister pack is any of several types of pre-formed plastic packaging used for small consumer goods, foods, and for pharmaceuticals.

Potentially Hazardous Food is a term used by food safety organizations to classify foods that require time-temperature control to keep them safe for human consumption. A PHF is a food that:

<span class="mw-page-title-main">Food packaging</span> Enclosure and protection of nutritional substances for distribution and sale

Food packaging is a packaging system specifically designed for food and represents one of the most important aspects among the processes involved in the food industry, as it provides protection from chemical, biological and physical alterations. The main goal of food packaging is to provide a practical means of protecting and delivering food goods at a reasonable cost while meeting the needs and expectations of both consumers and industries. Additionally, current trends like sustainability, environmental impact reduction, and shelf-life extension have gradually become among the most important aspects in designing a packaging system.

<span class="mw-page-title-main">Plastic bottle</span> Narrow-necked container

A plastic bottle is a bottle constructed from high-density or low density plastic. Plastic bottles are typically used to store liquids such as water, soft drinks, motor oil, cooking oil, medicine, shampoo, milk, ink, etc. They come in a range of sizes, from very small bottles to large carboys. Consumer blow molded containers often have integral handles or are shaped to facilitate grasping.

Aseptic processing is a processing technique wherein commercially thermally sterilized liquid products are packaged into previously sterilized containers under sterile conditions to produce shelf-stable products that do not need refrigeration. Aseptic processing has almost completely replaced in-container sterilization of liquid foods, including milk, fruit juices and concentrates, cream, yogurt, salad dressing, liquid egg, and ice cream mix. There has been an increasing popularity for foods that contain small discrete particles, such as cottage cheese, baby foods, tomato products, fruit and vegetables, soups, and rice desserts.

The terms active packaging, intelligent packaging, and smart packaging refer to amplified packaging systems used with foods, pharmaceuticals, and several other types of products. They help extend shelf life, monitor freshness, display information on quality, improve safety, and improve convenience.

To reduce the cost to the military of maintaining stockpiles of certain pharmaceuticals, the United States Department of Defense and the Food and Drug Administration operate a joint initiative known as the Shelf-Life Extension Program (SLEP), which evaluates the long-term effectiveness of medications stockpiled by the DoD and other government agencies. The program was established in 1986.

<span class="mw-page-title-main">Drug packaging</span> Packaging for pharmaceutical preparations

Drug packaging is process of packing pharmaceutical preparations for distribution, and the physical packaging in which they are stored. It involves all of the operations from production through drug distribution channels to the end consumer.

A temperature data logger, also called temperature monitor, is a portable measurement instrument that is capable of autonomously recording temperature over a defined period of time. The digital data can be retrieved, viewed and evaluated after it has been recorded. A data logger is commonly used to monitor shipments in a cold chain and to gather temperature data from diverse field conditions.

<span class="mw-page-title-main">Puffcorn</span> Puffed or extruded corn snacks

Puffcorn or corn puffs are puffed or extruded corn snacks made with corn meal, which can be baked or fried.

<span class="mw-page-title-main">Expiration date</span> Determined date to end the use of something

An expiration date or expiry date is a previously determined date after which something should no longer be used, either by operation of law or by exceeding the anticipated shelf life for perishable goods. Expiration dates are applied to selected food products and to some other manufactured products like infant car seats where the age of the product may impact its safe use.

<span class="mw-page-title-main">Cosmetic packaging</span> Packaging for cosmetics

The term cosmetic packaging is used for containers and secondary packaging of fragrances and cosmetic products. Cosmetic products are substances intended for human cleansing, beautifying and promoting an enhanced appearance without altering the body's structure or functions.

Drug expiration is the date after which a drug might not be suitable for use as manufactured. Consumers can determine the shelf life for a drug by checking its pharmaceutical packaging for an expiration date.

References

  1. ↑ Oxford English Dictionary, 2nd ed.
  2. ↑ Forcinio, Hallie (2 October 2018). "Protecting Solid-Dose Shelf Life". Pharmaceutical Technology. Vol. 42, no. 10. UBM. Retrieved 8 November 2018.
  3. ↑ 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)
  4. ↑ Gyesley, S. W. (January 1991). "Total System Approach to Predict Shelf Life of Packaged Food Products". In Henyon, DK (ed.). Total Systems Approach to Predict Shelf Life of Packaged Foods. ASTM International.: Food Packaging Technology. pp. 46–50. doi:10.1520/STP14842S. ISBN   978-0-8031-1417-3. ASTM STP 1113-EB.
  5. 1 2 "Food_Product_Dating" . Retrieved 2015-04-24.
  6. ↑ See "Expiration dates". Consumer Affairs. Retrieved 11 November 2011.
  7. ↑ Azanha, A.B.; Faria (July 2005). "Use of mathematical models for estimating the shelf-life of cornflakes in flexible packaging". Packaging Technology and Science. 18 (4): 161–222. doi: 10.1002/pts.686 . S2CID   136702424.
  8. ↑ "Can You Drink Milk Past Its Sell-by Date?". Dairy Council of California. Retrieved 30 May 2017.
  9. ↑ Pomerantz, JM (2004). "Recycling expensive medication: why not?". MedGenMed. 6 (2): 4. PMC   1395800 . PMID   15266231.
  10. ↑ 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).
  11. ↑ "US Army Medical Materiel Agency (USAMMA)". Usamma.army.mil. 2013-11-20. Archived from the original on 2015-03-18. Retrieved 2014-02-08.
  12. ↑ "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.
  13. ↑ "Essentialdrugs.org". Essentialdrugs.org. Archived from the original on 2013-12-11. Retrieved 2014-02-08.
  14. ↑ "Stockpiled Antivirals at or Nearing Expiration". Fda.gov. Retrieved 2014-02-08.
  15. ↑ http://www.usamma.army.mil/assets/docs/dlar.pdf Archived 2017-12-09 at the Wayback Machine [ bare URL PDF ]
  16. ↑ "The DoD Shelf-Life Program - Shelf-Life Management Manual - Definitions". Archived from the original on 2007-01-01.
  17. ↑ Public Affairs Office (June 4, 2004). "Nanotechnology applied to ration packaging" (Press release). Natick, MA: United States Army Soldier Systems Center. Archived from the original on October 26, 2018. Retrieved September 28, 2010.
  18. ↑ Meyers, T (June 2007). "RFID Shelf-life Monitoring Helps Resolve Disputes". RFID Journal. Archived from the original on May 11, 2008.
  19. 1 2 Forcinio, Hallie (2 October 2018). "Protecting Solid-Dose Shelf Life". Pharmaceutical Technology. Vol. 42, no. 10. UBM. Retrieved 8 November 2018.
  20. ↑ Archived May 16, 2012, at the Wayback Machine

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