Apart from air and water humans require both natural and man-made commodities for sustenance. Foods and pharmaceuticals constitute the major chunk of such commodities.All manmade products for human consumption reach you with an expiry date which is decided by the manufacturer on the basis of stability of the product under normal storage conditions. Preservatives are added in specified doses to most of the commercial products meant for human consumption as these help prolong the useful life of the product but even then all products cannot be stored for consumption indefinitely and have a shelf life.
What is shelf life?
Shelf life is the maximum time that a product can be used safely without any side effects under specified environmental conditions of temperature, moisture and exposure to light. It is a rough indicator for safe consumption. A food or drug does not become unsafe overnight after lapse of expiry date provided it is stored under the recommended conditions. It is important to differentiate between shelf life and date of expiration of foods. One should not consume any food after the expiration date.
Shelf life is dependent on storage conditions and growth of microorganisms. Such growths are promoted in foods exposed to higher humidity. One should be careful when consuming milk or other dairy products as harmful bacteria if already present result in faster decay even before expiration date and lead to food poisoning. On the other hand for pharmaceuticals the expiration date mentioned on the labels guarantees the full potency and safety claims of the drug within this period under the prescribed conditions.
Criteria for Stability studies
Stability studies play a vital role in estimation of shelf life of a product under controlled environmental conditions such as humidity, temperature, exposure to light, etc. The product is exposed to the defined conditions for the required time in stability chambers and important parameters such as concentration, active ingredient, appearance, colour change, growth of moulds or bacteria, etc are recorded at defined intervals. Based on such results the shelf life of the product is decided. Such data also proves useful for product development. The conditions of tests can be modified to include accelerated studies. Subsequent articles will cover the commonly used conditions and parameters tested for conducting stability studies of pharmaceuticals, foods and other consumer products.
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