Shelf life
Overview
Shelf life is the length of time that food
Food
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...

, drink, medicine
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, chemicals, and many other perishable
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...

 items are given before they are considered unsuitable for sale, use, or consumption
Eating
Eating is the ingestion of food to provide for all organisms their nutritional needs, particularly for energy and growth. Animals and other heterotrophs must eat in order to survive: carnivores eat other animals, herbivores eat plants, omnivores consume a mixture of both plant and animal matter,...

. In some regions, a best before, use by or freshness date is required on packaged perishable foods.

Shelf life is the recommendation of time that products 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.

Most shelf life dates are used as guidelines based on normal and expected handling and exposure to temperature.
Encyclopedia
Shelf life is the length of time that food
Food
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...

, drink, medicine
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, chemicals, and many other perishable
Decomposition
Decomposition is the process by which organic material is broken down into simpler forms of matter. The process is essential for recycling the finite matter that occupies physical space in the biome. Bodies of living organisms begin to decompose shortly after death...

 items are given before they are considered unsuitable for sale, use, or consumption
Eating
Eating is the ingestion of food to provide for all organisms their nutritional needs, particularly for energy and growth. Animals and other heterotrophs must eat in order to survive: carnivores eat other animals, herbivores eat plants, omnivores consume a mixture of both plant and animal matter,...

. In some regions, a best before, use by or freshness date is required on packaged perishable foods.

Shelf life is the recommendation of time that products 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.

Most shelf life dates are used as guidelines based on normal and expected handling and exposure to temperature. Use prior to the expiration date does not necessarily guarantee the safety of a food or drug, and a product is not always dangerous nor ineffective after the expiration date.

Shelf life

Shelf life is different from expiration date; the former relates to food quality
Food quality
Food quality is the quality characteristics of food that is acceptable to consumers. This includes external factors as appearance , texture, and flavour; factors such as federal grade standards and internal .Food quality in the United States is enforced by the Food Safety Act 1990...

, the latter to food safety
Foodborne illness
Foodborne illness is any illness resulting from the consumption of contaminated food, pathogenic bacteria, viruses, or parasites that contaminate food, as well as chemical or natural toxins such as poisonous mushrooms.-Causes:Foodborne illness usually arises from improper handling, preparation, or...

. A product that has passed its shelf life might still be safe, but quality is no longer guaranteed. In most food stores, shelf life is maximized by using stock rotation
Stock rotation
Stock rotation is the practice, used in hospitality and retail, especially in food stores such as restaurants and supermarkets, of moving products with an earlier sell-by date to the front of a shelf , so they get picked up and sold first, and of moving products with a later sell-by date to the...

, which involves moving products with the earliest sell by date to the front of the shelf, meaning that most shoppers will pick them up first and so getting them out of the store. This is important, as some stores can be fined for selling out of date products, and most if not all will have to mark such products down as wasted
Food waste
Food waste or food loss is food that is discarded or lost uneaten. As of 2011, 1.3 billion tons of food, about one third of the global food production, are lost or wasted annually. Loss and wastage occurs on all steps in the food supply chain...

, leading to a loss of profit.

Shelf life is most influenced by several factors: exposure to light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...

 and heat
Heat
In physics and thermodynamics, heat is energy transferred from one body, region, or thermodynamic system to another due to thermal contact or thermal radiation when the systems are at different temperatures. It is often described as one of the fundamental processes of energy transfer between...

, transmission of gas
Gas
Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...

es (including humidity), mechanical stresses
Stress (physics)
In continuum mechanics, stress is a measure of the internal forces acting within a deformable body. Quantitatively, it is a measure of the average force per unit area of a surface within the body on which internal forces act. These internal forces are a reaction to external forces applied on the body...

, 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).

For some foods, the shelf life is an important factor to health. Bacterial contaminants are ubiquitous, and foods left unused too long will often acquire substantial amounts of bacterial colonies and become dangerous to eat, leading to food poisoning. However, the shelf life itself is not an accurate indicator to the food safety. For example, pasteurized milk can remain fresh for five days after its sell-by date if it is refrigerated properly. In contrast, if milk already has harmful bacteria, the use-by dates become irrelevant.

The expiration date of pharmaceuticals specifies the date the manufacturer guarantees the full potency and safety of a drug. Most medications are potent and safe after the expiration date. A rare exception is a case of renal tubular acidosis purportedly caused by expired tetracycline. A study conducted by the U.S. Food and Drug Administration covered over 100 drugs, prescription and over-the-counter. The results showed about 90% of them were safe and effective as far 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.

Preservative
Preservative
A preservative is a naturally occurring or synthetically produced substance that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent decomposition by microbial growth or by undesirable chemical changes....

s and antioxidant
Antioxidant
An antioxidant is a molecule capable of inhibiting the oxidation of other molecules. Oxidation is a chemical reaction that transfers electrons or hydrogen from a substance to an oxidizing agent. Oxidation reactions can produce free radicals. In turn, these radicals can start chain reactions. When...

s may be incorporated into some food and drug products to extend their shelf life. Some companies use induction sealing
Induction sealing
Induction sealing, otherwise known as cap sealing, is a non-contact method of heating a metallic disk to hermetically seal the top of plastic and glass containers. This sealing process takes place after the container has been filled and capped.-How it works:...

 and vacuum
Vacuum
In everyday usage, vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty". A perfect vacuum would be one with no particles in it at all, which is impossible to achieve in...

/oxygen-barrier pouches to assist in the extension of the shelf life of their products where oxygen causes the loss.

Some degradation factors can be controlled by use of appropriate packaging. For example, the amber bottle used for many beers blocks damaging wavelengths of light. Transparent beer bottles do not. Packaging with barrier materials (e.g. low moisture vapor transmission rate
Moisture Vapor Transmission Rate
Moisture vapor transmission rate , also water vapor transmission rate , is a measure of the passage of water vapor through a substance....

, etc.) extends the shelf life of some foods and pharmaceuticals.

The United States Department of Defense (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.)


Shelf life is often described in conjunction with a specific product, package, and distribution system. For example, An MRE
MRE
The Meal, Ready-to-Eat — commonly known as the MRE — is a self-contained, individual field ration in lightweight packaging bought by the United States military for its service members for use in combat or other field conditions where organized food facilities are not available...

 field ration is designed to have a shelf life of three years at 80°F and six months at 100°F.

Temperature control

Nearly all chemical reactions will occur (at various rates depending on the individual nature of the reaction) at common temperatures. The degradation of foods and pharmaceuticals is usually accelerated by exposure to high temperatures. Another example is the breakdown of many chemical explosives into more unstable compounds. Nitroglycerine is notorious. Old explosives
Explosive material
An explosive material, also called an explosive, is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure...

 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
Rubber
Natural rubber, also called India rubber or caoutchouc, is an elastomer that was originally derived from latex, a milky colloid produced by some plants. The plants would be ‘tapped’, that is, an incision made into the bark of the tree and the sticky, milk colored latex sap collected and refined...

 products also degrade as sulphur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 bonds
Chemical bond
A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...

 induced during vulcanization
Vulcanization
Vulcanization or vulcanisation is a chemical process for converting rubber or related polymers into more durable materials via the addition of sulfur or other equivalent "curatives." These additives modify the polymer by forming crosslinks between individual polymer chains. Vulcanized material is...

 revert; this is why old rubber band
Rubber band
A rubber band is a short length of rubber and latex formed in the shape of a loop and is commonly used to hold multiple objects together...

s and other rubber products soften and get crispy, and lose their elasticity as they age.

These breakdown processes characteristically happen more quickly at higher temperatures. The usually quoted rule of thumb
Rule of thumb
A rule of thumb is a principle with broad application that is not intended to be strictly accurate or reliable for every situation. It is an easily learned and easily applied procedure for approximately calculating or recalling some value, or for making some determination...

 is that chemical reactions double their rate for each temperature increase of 10 degrees Celsius (°C) because of activation energy
Activation energy
In chemistry, activation energy is a term introduced in 1889 by the Swedish scientist Svante Arrhenius that is defined as the energy that must be overcome in order for a chemical reaction to occur. Activation energy may also be defined as the minimum energy required to start a chemical reaction...

 barriers become more easily surmounted at higher temperatures. However, as with all rules of thumb, there are many caveat
Caveat
Caveat , the third-person singular present subjunctive of the Latin cavere, means "warning" ; it can be shorthand for Latin phrases such as:...

s and assumptions. This particular one is most applicable to reactions with activation energy
Activation energy
In chemistry, activation energy is a term introduced in 1889 by the Swedish scientist Svante Arrhenius that is defined as the energy that must be overcome in order for a chemical reaction to occur. Activation energy may also be defined as the minimum energy required to start a chemical reaction...

 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, e.g., storing a product for one month at 35 °C simulates three months at 20 °C. There is enough variation that this practical rule cannot be routinely relied upon.

The same is true, to a point, of the chemical reactions of life. They are usually enzymatically
Enzyme
Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 catalyzed which changes reaction rates, but with constant catalytic action, the rule of thumb is still mostly applicable. In the particular case of bacteria and fungi, the reactions needed to feed and reproduce increase at higher temperatures, up to the point that the proteins and other compounds in their cells themselves begin to break down, or denature
Denaturation (biochemistry)
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent , or heat...

, so quickly that they cannot be replaced. This is the reason 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. This is the reason shelf life is generally extended by temperature control: (refrigeration
Refrigeration
Refrigeration is a process in which work is done to move heat from one location to another. This work is traditionally done by mechanical work, but can also be done by magnetism, laser or other means...

, insulated shipping container
Insulated shipping container
Insulated shipping containers are a type of packaging used to ship temperature sensitive products such as foods, pharmaceuticals, and chemicals. They are used as part of a cold chain to help maintain product freshness and efficacy...

s, controlled cold chain
Cold chain
A cold chain is a temperature-controlled supply chain. An unbroken cold chain is an uninterrupted series of storage and distribution activities which maintain a given temperature range...

, etc.) and the reason some medicines and foods must be refrigerated.

Temperature data logger
Data logger
A data logger is an electronic device that records data over time or in relation to location either with a built in instrument or sensor or via external instruments and sensors. Increasingly, but not entirely, they are based on a digital processor...

s, RFID tags and Time Temperature Indicators can record the temperature history of a shipment to help determine the remaining shelf life.

Best before

Best before or best by dates appear on a wide range of frozen, dried, tinned and other foods. These dates are only advisory and refer to the quality of the product, in contrast with use by dates, which indicate that the product is no longer safe to consume after the specified date. In spite of this, about a third of food bought is thrown away while still edible. In fact, food kept past the best before date will not necessarily be harmful, but may begin to lose its optimum flavour and texture. Eggs are a special case, since they may contain salmonella
Salmonella
Salmonella is a genus of rod-shaped, Gram-negative, non-spore-forming, predominantly motile enterobacteria with diameters around 0.7 to 1.5 µm, lengths from 2 to 5 µm, and flagella which grade in all directions . They are chemoorganotrophs, obtaining their energy from oxidation and reduction...

, which multiplies over time; they should therefore not be eaten after the best before date, which is a maximum of 28 days after the eggs are laid. Eggs must be sold to the consumer within 21 days of laying; this means that they must be sold 7 days before the 'best before' date expires.

Sometimes the packaging process involves using pre-printed labels, making it impractical to write the best before date in a clearly visible location. In this case, a term like best before see bottom or best before see lid might be printed on the label and the date marked in a different location as indicated.

Use by

Generally, foods that have a use by date written on the packaging must not be eaten after the specified date. This is because such foods usually go bad quickly and may be injurious to health if spoiled. It is also important to follow storage instructions carefully for these foods (for example, product must be refrigerated
Refrigeration
Refrigeration is a process in which work is done to move heat from one location to another. This work is traditionally done by mechanical work, but can also be done by magnetism, laser or other means...

).

Foods that have a best before date are usually safe to eat after the date has passed, although they are likely to have deteriorated either in flavour, texture, appearance or nutrition.

Bathroom products/toiletries usually state a time in months by which, once the product is opened, they should be used. This is often indicated by a graphic of an open tub
Period-after-opening symbol
The period-after-opening symbol or PAO symbol is a graphic symbol that identifies the useful lifetime of a cosmetics product after its package has been opened for the first time...

, with the number of months written inside (e.g., "12M" means use the product within 12 months of opening).

Open dating

Open Dating is the use of a date or code stamped on the package of a food product to help determine how long to display the product for sale. It is also beneficial to the customer and ensures that the product is at its best quality when bought. An Open Date does not supersede a Use by date, which should still be followed.

Sell by / Display until

These dates are intended to help keep track of the stock in stores. Food that has passed its sell by or display until date, but is still within its use by / best before will still be edible, assuming it has been stored correctly. It is common practice in large stores to throw away such food, as it makes the stock control process easier. It also reduces the risk of customers buying food without looking at the date, only to find out the next day that they cannot use it. Tampering with the posted date is illegal in many countries.

Most stores will rotate stock
Stock rotation
Stock rotation is the practice, used in hospitality and retail, especially in food stores such as restaurants and supermarkets, of moving products with an earlier sell-by date to the front of a shelf , so they get picked up and sold first, and of moving products with a later sell-by date to the...

 by moving the products with the earliest dates to the front of shelving units, which allows them to be sold first and saving them from having to be either marked down or thrown away, both of which contribute to a loss of profit.

Issues associated with sell by / use by dates

According to the UK Waste & Resources Action Programme
Waste & Resources Action Programme
WRAP works with businesses, individuals and communities to help them reap the benefits of reducing waste, developing sustainable products and using resources in an efficiency way....

 (WRAP), 33% percent of all food produced is wasted along the chill chain or by the consumer . At the same time, a large number of people get sick every year due to spoiled food. According to the WHO
Who
Who may refer to:* Who , an English-language pronoun* who , a Unix command* Who?, one of the Five Ws in journalism- Art and entertainment :* Who? , a 1958 novel by Algis Budrys...

 and CDC
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...

, every year in the USA there are 76 million foodborne illness
Foodborne illness
Foodborne illness is any illness resulting from the consumption of contaminated food, pathogenic bacteria, viruses, or parasites that contaminate food, as well as chemical or natural toxins such as poisonous mushrooms.-Causes:Foodborne illness usually arises from improper handling, preparation, or...

es, leading to 325,000 hospitalizations and 5,000 deaths.

According to former UK minister Hilary Benn
Hilary Benn
Hilary James Wedgwood Benn is a British Labour Party politician who has been the Member of Parliament for Leeds Central since 1999. He served in the Cabinet as Secretary of State for International Development from 2003 to 2007 and as the Secretary of State for Environment, Food and Rural Affairs...

, the use by date and sell by dates are old technologies that are outdated and should be replaced by other solutions or disposed of altogether. The UK government's Department for Environment, Food and Rural Affairs
Department for Environment, Food and Rural Affairs
The Department for Environment, Food and Rural Affairs is the government department responsible for environmental protection, food production and standards, agriculture, fisheries and rural communities in the United Kingdom...

 revised guidance in 2011 to exclude the use of sell by dates. The guidance was prepared in consultation with the food industry, consumer groups, regulators, and Waste & Resources Action Programme
Waste & Resources Action Programme
WRAP works with businesses, individuals and communities to help them reap the benefits of reducing waste, developing sustainable products and using resources in an efficiency way....

 (WRAP). It aims to reduce the annual £12bn of wasted supermarket food.

US Government guidelines

The Food and Drug Administration, which regulates packaged foods and drugs, only requires a use-by, or expiration, date on infant formula and some baby foods, because formula must contain a certain quantity of each nutrient as described on the label. If formula is stored too long, it loses its nutritional quality, and also separates or form lumps that will clog the bottle nipple. Except for infant formula and some baby foods, product dating is not required by FDA regulations.

The Agriculture Department (USDA), which regulates fresh poultry and meats, only requires labeling of the date when poultry is packed. However, many manufacturers also add sell-by or use-by dates.

The DoD Shelf-Life Program operates under the DoD Regulation 4140.1-R, DoD Materiel Management Regulation,

A. There are items in the Department of Defense (DoD) and the Federal Supply System that require special handling due to certain deteriorative characteristics. These items are to be properly maintained to ensure that the customer is provided fresh, useable materiel. The purpose of this Manual is to establish a shelf-life program and process, with special emphasis on those items having these known deterioration characteristics, to mitigate the risk of shelf-life expiration and lapses of shelf-life items/materiel beyond their inspect/test dates.

B. Provide policy and basic procedures for the management of both non-consumable and consumable shelf‑life items that may be hazardous material (HAZMAT) or non-hazardous material, spanning all classes of supply and stored at all levels of the Federal Supply System. Shelf-life management for hazardous materiel follows the same procedures as those for any shelf-life items, except that hazardous materiel should receive priority processing over non-hazardous materiel. Issues and guidelines concerning the acquisition, storage, handling, transportation, and disposal of hazardous materiel are addressed in Chapters 3 and 5 of this Manual. Class I perishable subsistence, Class III bulk petroleum, Class V ammunition, and Class VIII-B blood, are excluded from this Manual and shall continue to be managed in accordance with existing regulations. Commodities excluded from this Manual may be represented by their respective DoD Component to the DoD Shelf-Life Board. The definitions for “classes of supply” may be found in Appendix 16 of DoD 4140.1-R.

C. This Manual endorses the pollution prevention measures in DoD Instruction 4715.4 for hazardous materiel (HAZMAT) minimization (HAZMIN), as well as, the establishment of hazardous materiel control and management (HMC&M) philosophies which include consolidation and reutilization practices that embrace HAZMIN and HAZMAT elimination to reduce the hazardous waste (HW) stream.

D. Appendices A through K augment this Manual and furnish additional information germane to the DoD Shelf-Life Management Program. Appendix L serves as a quick reference index to this Manual.

Freshness date

A freshness date is the date used in the American brewing industry to indicate either the date the beer was bottled or the date before which the beer should be consumed.

Beer is perishable. It can be affected by light, air, or the action of bacteria. Although beer is not legally mandated in the USA
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 to have a shelf life, freshness dates serve much the same purpose and are used as a marketing tool.

Beginnings of freshness dating

General Brewing Company of San Francisco marketed their Lucky Lager
Lucky Lager
Lucky Lager is a beer that has a strong cult following on Vancouver Island. At one time Lucky was actually brewed on Vancouver Island in Victoria but in 1982 Labatt Breweries of Canada moved off the Island and proceeded to tear down the brewery to prevent any competition on the Island...

 Beer as "Age Dated" as early as late 1935. They stamped a date on each can lid to indicate that the beer was brewed before that date. This was not to insure that the beer was "fresh" but to insure that it had been aged properly. So many breweries had rushed beer to market before it was ready when Prohibition ended, that customers were wary of getting "green" beer.
The Boston Beer Company
Boston Beer Company
Samuel Adams is an American brand of beer brewed by the Boston Beer Company and its associated contract brewers. The company was founded in 1984 by Jim Koch, Harry M. Rubin, and Lorenzo Lamadrid in Boston, Massachusetts, USA...

, maker of Samuel Adams
Samuel Adams (beer)
Samuel Adams is an American brand of beer brewed by the Boston Beer Company and its associated contract brewers. The company was founded in 1984 by Jim Koch, Harry M. Rubin, and Lorenzo Lamadrid in Boston, Massachusetts, USA...

, was among the first contemporary brewers to start adding freshness dates to their product line in 1985. For ten years there was a slow growth in brewers adding freshness dates to their beer. The practice rapidly grew in popularity after the Anheuser-Busch
Anheuser-Busch
Anheuser-Busch Companies, Inc. , is an American brewing company. The company operates 12 breweries in the United States and 18 in other countries. It was, until December 2009, also one of America's largest theme park operators; operating ten theme parks across the United States through the...

 company's heavily marketed "Born-On dates" starting in 1996. Many other brewers have started adding freshness dates to their products, but there is no standard for what the date means. For some companies, the date on the bottle or can will be the date that the beer was bottled; others have the date by which the beer should be consumed.

Processing

Before a beer is bottled, it is process
Food processing
Food processing is the set of methods and techniques used to transform raw ingredients into food or to transform food into other forms for consumption by humans or animals either in the home or by the food processing industry...

ed to prolong its shelf life; this evidently affects the beer's freshness date. It may be done in several ways, not all of which will be used by a particular brewery:
  • Pasteurisation
    Pasteurization
    Pasteurization is a process of heating a food, usually liquid, to a specific temperature for a definite length of time, and then cooling it immediately. This process slows microbial growth in food...

     is a process by which a liquid is heated for a brief time to kill microbes that may be in the liquid. Pasteurisation has also been used for many years to keep milk safe for drinking due to bacteria that may be present.

  • Sterile filtration, in which the beer is passed through a mechanical filtration system which removes anything larger than 0.5 micrometre
    Micrometre
    A micrometer , is by definition 1×10-6 of a meter .In plain English, it means one-millionth of a meter . Its unit symbol in the International System of Units is μm...

    s. This removes any yeast
    Yeast
    Yeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with 1,500 species currently described estimated to be only 1% of all fungal species. Most reproduce asexually by mitosis, and many do so by an asymmetric division process called budding...

     or hops
    Hops
    Hops are the female flower clusters , of a hop species, Humulus lupulus. They are used primarily as a flavoring and stability agent in beer, to which they impart a bitter, tangy flavor, though hops are also used for various purposes in other beverages and herbal medicine...

     that may still be in the beer which would continue to react with it.

  • Bottle conditioning
    Bottle conditioning
    Bottle conditioned beers are either unfiltered so the final conditioning of the beer takes place in the bottle, or filtered and then reseeded with yeast so that an additional fermentation may take place.-Priming:...

     allows yeasts to remain in the beer after it is bottled. This helps prevent some oxidation
    Redox
    Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....

     of the beer.

  • Freshness longevity affects the time it takes a beer to become stale. Some of this depends on the type of beer ingredients included. If the beer has more hops and more alcohol than otherwise, it will stay fresh longer than those that are not as strong.

See also

  • Accelerated aging
    Accelerated aging
    Accelerated aging is testing that uses aggravated conditions of heat, oxygen, sunlight, vibration, etc. to speed up the normal aging processes of items. It is used to help determine the long term effects of expected levels of stress within a shorter time, usually in a laboratory by controlled...

  • Cold chain
    Cold chain
    A cold chain is a temperature-controlled supply chain. An unbroken cold chain is an uninterrupted series of storage and distribution activities which maintain a given temperature range...

  • Food waste
    Food waste
    Food waste or food loss is food that is discarded or lost uneaten. As of 2011, 1.3 billion tons of food, about one third of the global food production, are lost or wasted annually. Loss and wastage occurs on all steps in the food supply chain...

  • Modified atmosphere
    Modified atmosphere
    Modified atmosphere is the practice of modifying the composition of the internal atmosphere of a package in order to improve the shelf life....

  • Moisture vapor transmission rate
    Moisture Vapor Transmission Rate
    Moisture vapor transmission rate , also water vapor transmission rate , is a measure of the passage of water vapor through a substance....

  • Packaging and labelling
    Packaging and labelling
    Packaging is the science, art, and technology of enclosing or protecting products for distribution, storage, sale, and use. Packaging also refers to the process of design, evaluation, and production of packages. Packaging can be described as a coordinated system of preparing goods for transport,...

  • Permeation
    Permeation
    Permeation, in physics and engineering, is the penetration of a permeate through a solid, and is related to a material's intrinsic permeability...

  • Redox
    Redox
    Redox reactions describe all chemical reactions in which atoms have their oxidation state changed....

  • Shelf stable
    Shelf stable
    Shelf stable food is food of a type that would normally be stored refrigerated but which has been processed so that it can be safely stored in a sealed container at room or ambient temperature for a usefully long shelf life...


Further reading

  • Anonymous, "Cold Chain Management", 2003, 2006, http://www.iaph.uni-bonn.de/coldchain
  • Anon, Protecting Perishable Foods During Transport by Truck, USDA Handbook 669, 1995, http://www.ams.usda.gov/AMSv1.0/getfile?dDocName=STELDEV3021003
  • Kilcast, D., Subramamiam, P., "The Stability and Shelf-life of Food, Woodhead Publishing, 2000, ISBN 1 85573 500 8
  • Labuza, T. P., Szybist, L., "Open dating of Foods". 2001, Food and Nutrition Press, Trumbul CN; other edition: Wiley-Blackwell, 2004, ISBN 0917678532
  • Man, C. M., Jones. A. A., "Shelf-Life Evaluation of Foods", ISBN 0834217821
  • 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", ISBN 0841238014

External links

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