Shelf life study concept basic

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Shelf life, most of us agree that it is one of important aspect when it comes to buying a food product from your local supermarket. But, most of us still wonder that what this term actually mean?  Shelf life is the period of time within which the food is safe to consume without considerable change in organoleptic (taste, texture, odor, appearance), microbial spoilage and chemical changes when it stored at an appropriate temperature condition.  This generally indicated on food label by either a best before date or a use by date or an expiry date.

Food Safety Standard Authority of India (FSSAI) – lingo on shelf life:

According to FSSAI – Food Safety Standards (Packaging and Labelling) Regulation 2011 under section 2.2.2.10 all pre-packaged food products need to be mentioned the life of products by either a best before date or a use by date or expiry date.

Best Before date:

Reflects the length of a period a food can reasonably be expected to retain its best quality example: flavor, and taste.  This terminology generally used for a product which is longer shelf life more than three months example: Rice, Dried, and Frozen food.

Use by date 

Reflect the length of period food can reasonably be expected to be safe to consume when stored at an appropriate storage condition Example: Milk, Fresh poultry, and cooked meats.

Expiry date:

It pronounces similar meaning of use by date.  However, as per the FSSR 2011, on specific products such as “Aspartame, Infant food substitute, and Infant foods”.

Factor influencing the shelf life of a product:

What is the shelf life of my breakfast bread slices? Unfortunately, there is no straightforward answer to this question. Foods are perishable by nature. Upon storage for certain period of time, one or more quality attributes of a food may reach an undesirable state.  Therefore it is very important to control parameters influencing deterioration or spoilage. These factors are commonly known as the end of shelf life parameters (EOSL). However, there is a considerable difference in spoilage rate for a product to product. EOSL parameters can be broadly classified into two groups a) Microbial spoilage b) Non- Microbial spoilage

Microbial spoilage:

The growth of some of microorganism in food such bacteria,spoilage or food poisoning. The EOSL parameter determined by recommended Indian Food Safety regulation or guidance.

Non- microbial spoilage:

There is numerous way foods get deteriorated during the course of storage before it reaches to a consumer. Unlike to microbial spoilage, the results of deterioration not necessarily being harmful (food poisoning) but can certainly result in the foods no longer in an acceptable state. Some of the EOSLs are. I) Moisture gain or loss, II) Chemical change, III) light induced change, IV) temperature change, V) physical damage

Methodology:

There are two different test methods for conducting or determining a shelf life of product a) Direct method b) Indirect method

Direct method (Real time)

This is one of the commonly used methods. It involves storing the product under specific conditions for a period of time longer than expected shelf life and checking the product at regular intervals to see when it begins to spoil. As stated earlier procedure of the study is unique for each product

Indirect method (Accelerated)  

It allows for shelf life prediction without conducting full-fledged storage trial. It is very useful for the product has longer shelf life.  The two most common indirect method are a) accelerated shelf life studies b) predictive modelling.  The first indirect method (predictive modelling) uses information from a data base that predicts bacterial growth under preselected conditions which later used to calculate shelf life of a product.  The second indirect method (accelerated shelf life studies) involves intentionally increasing the product deterioration, through increasing the storage temperature.

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The tool used in accelerated studies is “the rule of ten” or Q₁₀, which is the factor by which the rate of spoilage increases when the temperature is raised by 10⁰ C. It is calculated with the following equation.

Q₁₀ = (R2/ R1) ⁽10 / (T2-T1⁾⁾

Planning the shelf life study:

Shelf life study must be planned in order to give an answer to some important following question:

  • Which types analyses must be carried out?
  • How many analyses must be carried out?
  • How many samples need to withdraw per analytical point?
  • Which period is most appropriate to perform the study?

Responsibility of calculating a shelf life

Food business operator involved in packages and sells food that is required to be date marked is legally responsible for calculating. Along with shelf life on the food label, it is mandatory to mention storage instruction / appropriate storage condition to meet that shelf life. Generally, it is perceived that this the responsibility of the manufacturer, but it can also be re-packers, secondary processors, food retailer, and supermarkets.

Reference:

  • Principles and methodologies for the determination of shelf life in foods – Antonio Valero, Elena Carrasco, and Rosa M Garcia Gimeno
  • A guide of calculating the shelf life
  • The process of conducting a shelf life study

 

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