This document discusses methods for estimating the shelf life of perishable foods. It defines perishable, semi-perishable, and non-perishable foods. The direct method for shelf life testing involves storing foods under expected conditions and monitoring deterioration over time, while the indirect method uses published data or past trials to estimate shelf life. Direct testing is preferred for highly perishable foods due to their short shelf life, while indirect testing can be used for foods with longer shelf lives. Sensory and objective laboratory tests are used to analyze deterioration during storage trials under optimum and realistic conditions.

1. By Sayanta Mitra

2.  Aim:
Estimation of Shelf Life of any highly perishable food.
 Principle:
Perishable:
Spoil quickly and should be refrigerated ASAP. Cooked foods
(leftovers) are perishable. Other perishable foods are meat, poultry, fish,
milk, eggs and many raw fruits and vegetables.
 Semi-Perishable:
Take longer to spoil and may or may not need immediate
refrigeration. Semi-perishable foods include onions and potatoes.

3.  Chilled food is food that is stored at refrigeration temperatures, which
are at or below 0 to −5 °C (32–23 °F). The key requirements for chilled
food products are good quality and microbiological safety at the point of
consumption.
 Date marking is the system for packaged foods with a shelf life of
less than two years.
 Best-before means the date until when, provided the food has been
stored in intact packaging and in accordance with stated storage conditions,
it will be fully marketable and retain its quality. The food will be safe to
eat after this date but may not be at its best. Its flavor and texture might
not be as good.
 Non-Perishable:
Will last for a while if stored properly, though they may lose
quality over time. Examples of non-perishable foods you may have in
your pantry are dried beans, canned soups, and spices.

4.  Shelf life is the period of time, established under intended conditions
of distribution, storage, retail and use that the food would remain safe and
suitable. Shelf life testing requires foods to be stored under the expected
conditions of storage and distribution for a period of time to determine at
what point chemical changes, deterioration and/or spoilage of the food
occurs.
 Shelf stable food is food of a type that, because of its composition (low
moisture, high salt or sugar concentration) does not require to be
refrigerated for storage or a food which would normally be stored
refrigerated but which has been processed so that it can be safely stored in a
sealed container at room temperature for a usefully long shelf life.

5. Use-by date is the date until when, provided the food has been stored in
intact packaging and in accordance with stated storage conditions, it is safe
to eat.
Shelf life testing
Direct method Indirect method
 Direct Method:
 These are real-time studies that consist of storing the product under
conditions similar to those that it will actually face, to monitor its evolution
in regular intervals of time.
 The main advantage of this method is that it creates a very accurate
estimation of the time it takes for a product to deteriorate.

6.  However, they are studies that usually take a long time and do not
consider the fact that storage conditions of a product are not always stable
over time. Although it’s very accurate but it is time consuming.
 Tests:
 Subjective or sensory testing:-
Color, textural, smell, changes. Test the food. Be careful about
food poisoning while taking or else we can skip the testing part.
 Objective lab testing:-
 Microbiology, indication of deterioration, are tested. If any material or
chemical has increased it shows deterioration. We can use publish
publication use past experience, or by matching other product. Then trial
run is done.

7.  After storage trial, the shelf life is coming as 10 days. Then addition trial
must be done after 10 days, how far at deterioration is taking place and how
it is working while marketing area.
 During storage trial, their difference conditions are observed.
I. Optimum condition: Maintain pH, temp., humidity at optimum
condition.
II. Under realistic condition: Subject product at temperature increased
and humidity and random fluctuation, a elevated temperature and
humidity fluctuation.

8. Discussion:
In perishable food direct testing is preferred as itself has a low shelf
life hence the direct process becomes easier. In case of low risk indirect testing
is done, as its shelf life is more hence, artificially shelf life is shortened.