Process Facts

Storage conditions and products quality

Storage conditions

Groceries and pharmaceuticals are especially sensitive to storage conditions. In case of frozen groceries and some pharmaceuticals (CRT), factors such as temperature and time have significant influence on preserving high quality and consumption usefulness (expire date), and what follows it – consumers’ safety. It should be remembered that expire date defines only the lifetime of a product when kept in ideal storage conditions. On the other hand, any exposure out of defined storage conditions has negative influence on quality of a product, which is difficult to define on the base of appearance and smell observed. Therefore, a hundred percent certainty of safety of a product can be ensured by constant monitoring of temperature and time changes, from the moment of production up to consumption. The only solution to the problem of constant monitoring of quality of a product is application of temperature indicator (TTI- time temperature indicator) directly on the product.

Factors having influence on lifetime of a product

A key-factor influencing the quality of groceries is a correlation of temperature in which the product is stored, together with the time in which this product is kept in a given temperature. It means that, the higher temperature in which the product is stored, the faster physical and biochemical processes which lower the product’s quality proceed e.g. the expire date placed on the packaging by the producer is most frequently given for the temperature -18˚C, (microbiological activity is suspended at this temperature) and yet storing it in -12˚C shortens the expire date up to 4 months, and storing in the temperature -6˚C up to 4 weeks. The complete defrosting of a product also depends on temperature and the time in which it is kept. Complete defrosting will occur much quicker at e.g. 20 ˚C than at 5˚C (size of a product also influences defrost time)

Visual relation between shelf life of a product and storage temperature
  • Groceries and pharmaceuticals have strictly defined expire date- time of consumption usefulness - but only in defined storage conditions
  • After exceeding the defined storage conditions, expire date is significantly shorter
  • In case of extreme exceeding of storage conditions, the product should be consumed immediately or in some cases it is incapable to be consumed
  • Placing the product in proper storage conditions again will not return its quality and durability
  • In case of frozen products - once being defrosted are incapable of being frozen again

Quality of frozen products

The basic conditions of good quality of frozen food are: clean, healthy, high quality raw products, proper preliminary preparation, proper freezing and storage parameters, proper packaging. Generally, frozen food keeps quality when obeying accurate rules of Good Producing Practice. It should be remembered though that at low temperatures, during the time of cooling storage, physical, chemical and biochemical changes still occur but in slow rate, and by degrees they cause a decrease in quality of frozen products. The character of quality changes is specific for the given group of products and consolidation technology being used. The most important physical changes that occur in frozen products are changes in the structure of products which are shown as the loss of turgor, decrease in firmness, weakening of product’s consistence, and loss of mass due to evaporation and sublimation of vapor. Chemical and biochemical changes are created mainly due to enzymes, which can be the cause of complicated reactions. Nutritive value of frozen products is also worsen due to decrease of vitamin C, vitamin from group B and others. Preserving proper quality of frozen food depends on conditions of storage i.e. temperature and humidity of air. Humidity of air in low temperatures is set spontaneously according to general balance of warmth and humidity, in normal conditions it is set in the range of 95,98%. Temperature is a decisive parameter, which characterizes the run of physical processes, kinetics of chemical and biochemical reactions and life activity of microorganisms. The function of storage temperature is a durability of frozen products i.e. the time in which quality changes do not exceed the assumed range. Presently -18˚C and lower is a temperature which on an international scale is considered as the maximum temperature of long-term storage of groceries, deeply frozen in appropriate industrial devices. In modern cooling objects the temperature of - 30˚C is widely used, and recently even lower temperature has been used for products especially susceptible to quality changes(e.g. some fish species). Storage temperatures that ensure obtaining the required durability level of frozen food should be treated as optimum.

Cold chain and HACCP legislation

Frozen products should be transported and stored in an unbroken cold chain. It means that, from the moment of production by the net of distributors up to the final consumers, they should be kept in proper temperatures. The exposure of a product to the temperatures out of the recommended range in any of the chain cell may result in lowering the quality of the product. In times when groceries travel through many kilometers and by different means of transport from producers to consumers, structures of cold chains develop significantly.

Monitoring of temperature

It is to remember, that the cold chain can be broken in any time. Although, that presently there are mechanical or electronic monitoring systems of transported or stored goods, the problem is left unsolved. These devices register only the temperature of the surrounding which is inside the mean of transport or storing place; however they do not register the temperature of the products. It is very easy to break the chain at the moment of e.g. reloading of goods. Therefore, very often there are a lot of misunderstandings on the line among the producer- transport company and distributor. It is also connected with the problem of taking responsibility for braking the cold chain and damage of goods.

TTI application

Application of temperature indicator directly on a single pack of a product or on a combined pack (more developed indicators) will allow for eliminating the threat of delivering the product not suitable for eating to the next cell of a cold chain –together with the consumer as the last cell of the chain.

HACCP Legislation

HACCP - Hazard Analysis and Critical Control Point – is done to ensure the safety of groceries designed for consumers. HACCP is used in companies producing and trading in groceries. This method ensures safety of food. It is based mainly on preventing the threats, by identification of places in which the threats may occur and the proper reaction in case of threat. HACCP legislation constrains the temperature monitoring for the products sensitive to its change. Therefore TTI indicators are an ideal tool that allows producers to fulfil this condition. The use of temperature indicators on the level of single or combined pack will ensure constant measurement of monitored product and will indicate the possible cold chain break.


In countries of the European Union, there is a duty of monitoring of temperature inside the means of transport, and storing temperatures of products deeply frozen. Deeply frozen food is the food that is treated by so-called – deep freezing , in which the zone of maximum crystallization is exceeded as quick as possible, and the final temperature of a product after thermal stabilization is constantly kept on the level of -18˚C or lower. In the countries of the European Union there are two regulations describing the production conditions and storage of food. These are Regulation no 852/2004 passed by the European Parliament and Council from the 29th of April 2004, establishing the special rules concerning hygiene as regards food derived from animals.


Even the best frozen product can quickly lose the proper quality due to even slight omission in storage process, transport or selling. The emphasis is put mainly on these cells of cold chain. It is so, because researches show that these are the points of potentially the biggest threat of decreasing the quality of frozen products.

Stock management

Expiration date based systems

Presently, stock systems in groceries industry which are most often used, are based on the date of production and the expire date. Not always, when we base the stock management on these data will we receive the optimal way of stock management. The problem may arise in case of a situation when part of the products was not kept in optimal storage conditions, which directly influences the lifetime and quality of a product. In such situation the expire date is significantly shorter and being followed by this date may lead to the situation in which goods taken from the store may reach the shop too late or may be useless. It is connected with big financial loss for producers and distributors and what is more important, with a decrease of quality and safety of products getting to the customer.

LSFO System

An alternative system is constant monitoring of product’s conditions by using TTI indicators. It allows for organizing a stock rotation in LSFO system - Last Shelf Life First Out. It is based on a consumption usefulness of a product and allows for letting out products with the shortest real consumption date. It also eliminates the threat of letting out the product not suitable for consumption on the market.

TTI requirements

TTI indicator in order to fulfill its tasks, to be used on a large scale, or to be a widely used standard must fit the following requirements:

Each active indicator must indicate exceeding of defined conditions in which the product exist.
Should be defined on the level +/-1˚C.
The indicator should be made of materials legalized to be used in the groceries and pharmaceutical packages specialty
The price should enable the indicator to be placed on each single product
The indicator should be applied in easy way enabling mass application. Applying machines should be integrated with production lines with ease
The indicators should be activated in an easy way enabling its mass use in the moment of applying it on a product
Before application, the indicator should be adjusted to be stored in room temperatures
Indication should be irreversible, legible and understandable by the consumer
parameters of indication should be properly matched to physical properties (mass, shape) and the kind of monitored product
Indicator should be resistant to physical, mechanical and chemical activities to which it can be exposed, in production process, transport and product’s storage. Its endurance should be at least as big as the endurance of the whole package
Indicator should be “sticked” to the product in such a way that it’s impossible to tear it off

Public opinion

Public opinion on TTI

The research done at the University of Minnesota show that 96% of people questioned claim, they would prefer to buy products with temperature indicators informing of the product’s quality.

The public opinion research done in Great Britain showed that the use of an indicator showing the exceed in the required temperature is an excellent idea. (J.P. Kerry*, M.N. O’ Grady, S.A. Hogan, Past, current and potential utilization of active and intelligent packaging systems for meat and muscle-based products: A review (2004).

According to marketing research the project done with the cooperation of the EU, regarding “Intelligent packaging”, German, Dutch and Spanish consumers are ready to pay more for the guaranty of freshness up to 6% more than the present price. Other research says about additional amount of 10 eurocents.

Experts opinion on TTI

Analysts claim, that in the near future TTI devices will without any doubt find a vast application in groceries industry, especially in meat industry - beef, pork, seafood, ready made meals etc. (J.P. Kerry*, M.N. O’ Grady, S.A. Hogan, Past, current and potential utilization of active and intelligent packaging systems for meat and muscle-based products: A review (2004).

Invenview Company is currently working on public opinion research regarding the use of temperature indicators in pharmaceutical or groceries industry. The results will be known soon.