question: Why do some products require refrigeration after opening, but can be on a shelf for long periods of time prior to?
comment: An item can be packed in such a way that specific conditions are maintained: such as the content being completely free of bacteria or not containing oxygen gas. Once opened, those conditions can no longer be upheld, and microbial growth and/or oxygen exposure will lead to product spoilage much quicker.
passages: Once opened for consumption, the product is immediately exposed to atmospheric oxygen and floating dust particles containing bacteria and mold spores, and all protections from the preservation process are immediately lost. At room temperature, mold and bacteria growth resumes almost immediately, and warmer temperatures can lead to an explosion of growth that rapidly degrades the food product. This organism growth can result in the accumulation of poisonous bacterial substances in the food product such as botulin, that lead to food poisoning, sickness, or death.
   BULLET::::- Keep the container closed and the contents contained for the specified shelf life until time of opening
  
  BULLET::::- Provide a barrier to dirt, oxygen, moisture, etc. Control of permeation is critical to many types of products: foods, chemicals, etc.
  
  BULLET::::- Keep the product secure from undesired premature opening
  
  BULLET::::- Provide a means of reclosing or reusing the container
  
  BULLET::::- Assist in dispensing and use of product
   Section::::Aseptic packaging.
  
  BiB is also used extensively in the packaging of processed fruit and dairy products in aseptic processes. Using aseptic packaging equipment, products can be packed in aseptic packaging. Pasteurised or UHT treated products packed into this format can be "shelf stable", requiring no refrigeration. Some products can have a shelf life of up to 2 years, depending on the type of bag that is used.
   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.
   Refrigerate after opening
  
  The term refrigerate after opening is an instruction on commercial preserved food products to cool the container after it has been opened and the contents exposed to open air.
  
  Moist foods are commonly preserved using canning and vacuum sealing to kill off any bacteria and molds, and to prevent further growth by removing oxygen. Dry-product containers are often preserved with heating and filling the empty container spaces with an inert nonreactive gas such as nitrogen.
   Depending on container size, 10 to 60 products can be displayed at once on a shelf. 
  
  To exploit the full potential savings of SRP, it may be removed from the shelf when the last article has been removed. This leads to gaps in the shelves that can affect the purchasing behaviour of customers. Through the use of an integrated product system, which pushes the remaining products to the front of the SRP whenever one product has been taken from it, shelf gaps can be reduced.
  
  Section::::See also.
  
  BULLET::::- Packaging and labeling
  
  BULLET::::- Merchandising
  
  Section::::External links.
  
  BULLET::::- Shelf Ready Packaging
   Newer jars of food tend to come with a plastic wrap around the edge of the lid, which is removed when opening, although the springy-cap designs are still in common use.
  
  Tamper-evident packaging also extends to protect stores; there are some scale labels for meats and deli products that will tear if removed.
   Secondary seals are common with sensitive products that may deteriorate or where extra security is needed. Foil or plastic innerseals are used on some bottles, Heat sealed lidding films are used on some tubs. External shrink bands, labels, and tapes are sometimes used outside the primary closure structure. Additionally, many closures feature ventilation to prevent bloating, collapse or explosion due to unequalized pressure during processing or storage. Venting technologies utilize common materials such as PTFE, PP, etc. These elements are preferred due to their ability to withstand temperatures of 260°C and water intrusion pressure levels of 770 mbar.
   Cooling the food product to a temperature just above freezing in a refrigerator is generally required to slow the growth of these organisms. This cooling can permit foods to remain safely edible for up to two weeks after opening.
  
  Simply loosening the lid of a vacuum-packed food product to break the seal is enough to permit the bacteria and mold growth to resume. The amount of air inhaled into the container when the seal is broken is small, but sufficient to permit slow growth of contaminating and decomposing organisms.
   Oxygen scavengers, carbon dioxide generators, ethanol generators, etc. are available to help keep the atmosphere in a package at specified conditions.
  
  Section::::Temperature monitor.
  
  Some temperature indicators give a visual signal that a specified temperature has been exceeded. Others, Time temperature indicators, signal when a critical accumulation of temperature deviation over time has been exceeded. When the mechanism of the indicator is tuned to the mechanism of product degradation, these can provide valuable signals for consumers.
   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.
   BULLET::::- Barrier protection – A barrier to oxygen, water vapor, dust, etc., is often required. Permeation is a critical factor in design. Some packages contain desiccants or oxygen absorbers to help extend shelf life. Modified atmospheres or controlled atmospheres are also maintained in some food packages. Keeping the contents clean, fresh, sterile and safe for the duration of the intended shelf life is a primary function. A barrier is also implemented in cases where segregation of two materials prior to end use is required, as in the case of special paints, glues, medical fluids, etc.
   Various food preservation and packaging techniques are used to extend a food's shelf life. Decreasing the amount of available water in a product, increasing its acidity, or irradiating or otherwise sterilizing the food and then sealing it in an air-tight container are all ways of depriving bacteria of suitable conditions in which to thrive. All of these approaches can all extend a food's shelf life, often without unacceptably changing its taste or texture.
   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
   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. Active packaging, on the other hand, employs the use of substances that scavenge, capture, or otherwise render harmless deleterious substances. 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.
   A digital Temperature data logger or a time temperature indicator is often enclosed to monitor the temperature inside the container for its entire shipment.
  
  Labels and appropriate documentation (internal and external) are usually required.
  
  Personnel throughout the cold chain need to be aware of the special handling and documentation required for some controlled shipments. With some regulated products, complete documentation is required.
  
  Section::::Design and evaluation.
  
  The use of “off the shelf” insulated shipping containers does not necessarily guarantee proper performance. Several factors need to be considered:
   Products must be clearly labeled by brand, name, stock keeping unit (SKU), etc. Bar codes and sometimes RFID tags must meet the retailer’s specification. 
  
  BULLET::::- 2 Easy Open
  
  All SRP solutions should be easy to open, in order to secure easier and quicker replenishment. Packaging needs to be secure enough to withstand distribution but allow easy opening, preferably without special tools or knives. Opening processes should be intuitive; pictograms are useful. 
  
  BULLET::::- 3 Easy Recycle/dispose
   Depending on the product, atmosphere, temperature, and the barrier properties of the package, vacuum packaging extends the shelf life of many foods. The shelf life of meats can be extended by vacuum packaging, particularly when used with modified atmosphere packaging.
  
  Section::::High barrier shrink vacuum bags.
   Closely related to the functional requirement "easy open" is the requirement of "easy shelf". Both requirements are intended to facilitate the replenishment of the shelves. To ensure proper replenishment, the SRP needs to be stable and should not lose its original shape.
  
  Integrated package handles can facilitate the placing of goods on shelves.
  
  SRP should be stackable and stable so that the space available on one shelf can be used efficiently.
  
  BULLET::::- 5 Easy Shop
   Shelf life is the length of time that a commodity may be stored without becoming unfit for use, consumption, or sale. In other words, it might refer to whether a commodity should no longer be on a pantry shelf (unfit for use), or just 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, chemicals, tires, 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.
   It should be acknowledged that a durable life date is NOT an indicator of food safety. Once something is opened, depending on how it is stored, the shelf life can change. For example, an open box of crackers meant to expire in two weeks, will expire much faster should the seal be left open after each use.
  
  Section::::Requirements.:Geographical indications.
   Many problems may occur when filling viscous media. The problems are often product-specific and are revealed when the product to be filled takes on an a-typical appearance. Examples of this are an inhomogeneous product appearance with sausage goods or when inserts are ground too finely during the pumping process.
  
  However commercial or legal problems can also arise, in the form of weight deviations or non-compliance with the specified quality regulations (e.g. the guidelines for meat products).
   Dairy products are constantly in need of refrigeration, and it was only discovered in the past few decades that eggs needed to be refrigerated during shipment rather than waiting to be refrigerated after arrival at the grocery store. Meats, poultry and fish all must be kept in climate-controlled environments before being sold. Refrigeration also helps keep fruits and vegetables edible longer.
   "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. 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 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 and six months at .
  
  Section::::Temperature control.
  
raw_presuppositions: After being opened a product's packaging can maintain the same conditions that it could when on a shelf.
raw_corrections: After being opened a product's packaging cannot uphold the same conditions that it could when on a shelf.