Shelf Life

Related Content
Changed on: 24.04.2019

With the expiry date (MHD), the manufacturer guarantees that the product, if properly stored, will retain its full fitness for human consumption at least until that date.

In general, exceeding the best-before date does not mean that a food is no longer fit for human consumption. This means that a food will usually keep longer than the best-before date indicates. How much longer, however, is difficult to predict in advance; it depends on the product and also on the storage of the product up to this point in time.

If there are no abnormalities in a sensory test (texture, appearance, smell) and the duration of the excess is short, there is no reason not to consume the product.

A significant difference exists if the packaging indicates a so-called consumption date ("to be consumed by"). Very perishable goods (e.g. fish and raw meat) have a consumption date. A product for which this date is exceeded is no longer considered safe. It should no longer be eaten but disposed of immediately.

With the expiry date (MHD), the manufacturer guarantees that the product, if properly stored, will retain its full fitness for human consumption at least until that date.

In general, exceeding the best-before date does not mean that a food is no longer fit for human consumption. This means that a food will usually keep longer than the best-before date indicates. How much longer, however, is difficult to predict in advance; it depends on the product and also on the storage of the product up to this point in time.

If there are no abnormalities in a sensory test (texture, appearance, smell) and the duration of the excess is short, there is no reason not to consume the product.

A significant difference exists if the packaging indicates a so-called consumption date ("to be consumed by"). Very perishable goods (e.g. fish and raw meat) have a consumption date. A product for which this date is exceeded is no longer considered safe. It should no longer be eaten but disposed of immediately.

Shopping and Storage

Pay attention to the freshness of the food. Perishable foods (fresh poultry meat, minced meat, fish, dairy products, etc.) should be transported home as quickly as possible after purchase. A warm car can help interrupt the cold chain. Therefore use cool bags for delicate food and frozen products to ensure that the food is transported sufficiently cool. Check the refrigerator and freezer temperatures regularly.

Foods for which the minimum durability date ("at least stable until...") has been exceeded are not automatically spoiled. It only means that the manufacturers guarantee that their products will be in perfect condition until then. After the expiration date, check that the product is fit for human consumption. Use your senses - see, smell, taste. You can then decide for yourself whether the food is still edible or not.

The consumption date ("to be consumed until...") indicates the deadline by which a food should be consumed. It is an expiration date with which perishable foods (e.g. meat, fish) are labelled. The following applies here: It is imperative that you adhere to the consumption date printed on it, otherwise you run the risk of food poisoning.

Ideally, different foods are stored in the refrigerator in separate, liquid-tight and clean containers (ideal: sealable cans).

This is how you should store your food in the Refrigerator

  • The glass plate above the vegetable compartment is the coldest place in the fridge. It is recommended to store sensitive food such as meat, fish or poultry in this area.
  • Raw meat and fish should be stored covered in appropriate containers. This prevents direct contact with other food in the refrigerator. The transfer of bacteria to other foods is thus prevented.
  • If the room temperature increases in summer, it may be necessary to change the setting of the cooling thermostat.
  • Check the internal temperature of your refrigerator with a thermometer. This slows down or stops the growth of bacteria. Storage below 5 °C is ideal. Follow the cooling recommendations of the manufacturer.
  • The refrigerator itself can also become a hygiene problem if it is not cleaned regularly. Use a household detergent with a good grease dissolving power.
  • Sweat water and moisture should be removed as far as possible, as germs need moisture to grow.

38 percent of the refrigerators examined have a temperature of over 8 °C. Only just under half of the respondents knew about the optimum refrigerator temperature of 1 to 5 °C. The temperature of the refrigerator is between 1 and 5 °C. Only less than one third set the refrigerator below 5°C.

Cleanliness is also important in deep freezers, freezer compartments or freezers. As long as food is unopened, liquid-tight and not soiled/fatty/tacky from the outside, the other food and the freezer are not contaminated. Compared to the refrigerator, the freezer has the advantage that pathogens cannot multiply at minus temperatures. However, many pathogens do not die at sub-zero temperatures and can multiply again after thawing.

Tips on the shelf life of foods

Moldy apple sauce

Correct handling of foodstuffs for which the minimum durability date (MHD) has already been exceeded.

The manufacturer guarantees that food can be eaten without hesitation up to the stated shelf life. However, food producers are very cautious about this, as the law stipulates that they must guarantee the greatest possible safety for consumers. The actual shelf life is therefore often longer.

Consider the following points when considering whether an expired food can still be eaten

  • Check appearance, smell and taste. You should take your time and know exactly what the food should be like. Beware of a cold!
  • Is the food originally closed or in an already opened package? Foods that are industrially produced and originally packaged come from a very clean environment. Therefore, they are contaminated with only a few germs and last longer than those in opened packs. After opening, however, you should use up food as quickly as possible.
  • Look at the properties of the food. Foods that are dry (flour, sugar, soup cubes, etc.), preserved (e.g. by high salt content such as anchovies, by high sugar content such as jam, etc.) or made long-lasting by heating (e.g. long-life milk, tins) do not spoil within days just because the shelf life has been exceeded. Animal products with a short shelf life (sliced sausage), on the other hand, are susceptible to spoilage and pathogens.
  • Think about what you want to do with the food. When heated thoroughly, germs are reliably killed off. Therefore, eggs that look and smell normal can be cooked hard or used for baking even after the specified MHD without hesitation. However, such eggs should never be eaten raw, e.g. as tiramisu.
  • Note that there are circumstances in life where you should be particularly careful. This is the case during pregnancy, with very young and very old people, with people who have serious illnesses or have to take medication that weakens the immune system. If one of these points applies to you, don't take any risks and follow the manufacturer's instructions!
  • Do you suffer from a histamine degradation disorder? In this case you should consume protein-containing foods, even if they have a long shelf life, e.g. hard cheese (e.g. Parmesan), only with as long a shelf life as possible and never after the minimum shelf life.

These tips only apply to foods with a best-before date. Foods with a consumption date "to consume until..." should not be eaten after the date has expired!

Signs of spoilage

If only one characteristic applies, consumption is not recommended.

  • Changes in smell and taste (rancid, mouldy, musty)
  • Visible mould growth (throw away the entire product)
  • Conspicuous consistency (moist, lumpy)
  • greasy Surface
  • discoloration, dried spots
  • insect infestation
  • Grating of containers / Lids
  • Inflating containers / preserves (never open them or throw them away)
  • freezer burn

Guidelines for shelf life

  • When shopping: Perishable foods (fresh poultry meat, minced meat, fish, dairy products, etc.) should be transported home as quickly as possible after shopping. A warm car can help interrupt the cold chain. Therefore use cooling bags for delicate foods and frozen products.
  • Store food at home according to the manufacturer's instructions.
  • Clean the fridge regularly. The glass top above the vegetable compartment is the coldest place in the fridge. Store sensitive foods such as meat, fish or poultry in this area.
  • The food must be visually inconspicuous.
  • The packaging must not be opened or damaged.
  • Fruit and vegetables should be unpacked from the foil. If left in the packaging, condensation can form which stimulates germ formation and can lead to mold growth.

Tips for avoiding food waste

  • more economical. Do not go hungry shopping. Write a list before every purchase.
  • Simply brush the rolls and pastries from the previous day with cold water and put them in the oven for about 10 minutes.Slice too much bread and freeze. Portionwise it can be baked in the toaster or in the oven.
  • Freeze the butter in portions.
  • Store separately: In addition to mould cheese, other cheese begins to mould more quickly. Apples release ethylene, which makes other types of fruit ripen faster. Therefore, store elsewhere.
  • Hard cheese, which has dried but still smells good, can, for example, be grated and processed in a casserole. However, heat up well.
  • Water test for eggs: How to do it - You can see how fresh a raw egg is by placing it in cold water. With increasing age the density decreases. If the egg goes under and remains flat on the ground, the egg is fresh. Slightly older eggs float in the water and should be processed and heated as soon as possible. Caution is advised when the egg is already floating on top or when the blunt tip protrudes from the water. In this case the egg is no longer suitable for consumption.

Mildew

Mildew, rot - No more eating!

caption
Moldy food
Mildewed ham

It is assumed that there are more than 100,000 different types of mould in the environment. In the course of evolution, humans have developed extensive resistance to fungi.

Mould fungus poisons (mycotoxins) belong to the strongest poisons occurring in nature. Not all moulds produce toxins. Nevertheless, several hundred mycotoxin-forming fungi and about 350 different toxins have been identified.

Even if the mould is cut out or spooned away, the food affected can be impaired. Possible poisons do not necessarily remain in the visible mold (fungus body), but can spread in the entire food. Large parts of a fungus are often invisible. The single hyphae, the thread-shaped cells of the fungus, are not to be recognized with free eye, can pull themselves however through the entire food. Without a suitable laboratory, it is not possible to detect toxin-forming moulds.

In summary it means therefore: mouldy food better to dispose in order to exclude a possible impairment of the health. Cooking is also no alternative due to the resistance of the poisons. Cutting away is to be recommended, if at all only with food such as bacon and hard cheese, at which the mold can grow only at the surface, (at least half a centimeter). If you want to be safe, it is better to dispose of mouldy food.

At home it is recommended to store food in a cool and dry place. Plastic foils should therefore be avoided, as condensation can form due to inadequate ventilation. Fruit and vegetables in particular are often sold packaged in plastic film. These films should be removed before storage in the refrigerator.

Focus on mould in sliced cheese (German)

 

Freezing Food

Tips for freezing

caption
Frozen raspberries

Preparation

The right preparation is important: cleaning, crushing, etc. can be done much better before freezing than after thawing, e.g. also breading mushrooms. Take a look at the instructions for your appliance. Many manufacturers provide valuable information in this manual. Numerous websites also provide detailed advice.

Blanch vegetables beforehand or not? A question of faith that is objectively difficult to answer. A certain amount of nutrients is already lost before blanching. On the other hand, the remaining nutrients (because the enzymes are deactivated), as well as colour and taste, are retained longer.

Rapid freezing process

Ensure that the freezing process is as rapid as possible, because this is where the greatest loss of quality occurs (slow growth of the ice crystals destroys the cell walls and thus damages the texture, the fruit becomes "muddy"). Switch the appliance to full cooling capacity a few hours before (a largely filled one better the day before). Do not freeze too large packs and fill the bags as flat as possible. Do not place them on top of each other when freezing; you can stack them afterwards to save space. Do not freeze too much at once. By the way: you can also buy frozen food.

Setting the storage temperature

Set the storage temperature to at least -18 °C, better still below. Then almost all foods should be kept in appropriate packaging for approx. 10 months. A longer storage period makes no sense anyway, as a freezer is not intended for bunker storage in times of emergency.

Defrosted food

Freeze thawed out again? From a microbiological point of view, no problem if something was just thawed or the defrosting phase was short. Bacteria hardly multiply at freezing temperatures, so there is no fear that this could damage your health. But the loss of quality can take on drastic proportions.

Packaging

Do not underestimate the influence of the packaging: Unsuitable or too thin materials can allow oxygen or odours to penetrate. After removing as much air as possible, ensure that the seal is as tight as possible. (Leaks or too much air will cause freeze burning. This causes the surface to dry out. This is not dangerous, but the enjoyment value suffers.) Vacuuming and welding is ideal, as is a knot in the tightly twisted end of the bag. A wire paper clip is not ideal. Use cans only if they are leak-proof even when frozen and can be filled as full as possible. Do not burden your freezer by freezing odour-intensive goods such as onions or garlic, this can take revenge on the frozen cake.

Last but not least, you can keep an overview by labelling and keeping things tidy.

Do not refreeze defrosted food!

Refrigerator

Defrosted food should not be refrozen: Pathogens may have multiplied during thawing; freezer burn is bad for quality.

Pathogens: Many pathogens do not die at sub-zero temperatures and can multiply again after thawing. Particularly delicate in this respect are perishable foods such as raw meat and fish or raw milk products. If too much raw meat/fish has been defrosted, the food should be completely cooked before freezing again (at least 70 °C for 2 minutes in the core of the food).

Frozen spirit: When food is frozen, the water contained in the cells freezes to ice crystals and destroys the cell walls. During thawing, this ice crystal also thaws and the food loses water. This results in a loss of weight and the prepared food is drier than freshly prepared food.
When frozen again, the thawing water forms larger ice crystals that destroy even more cells; the food then shows dry spots, the so-called freezer burn.
Products that are offered frozen on the market are usually shock frozen. These foods are cooled to the desired storage temperature - 18 °C or lower - within a very short time. This rapid process keeps the cell walls intact (only very small ice crystals are formed) and food retains its consistency and other properties such as flavours etc. The food is stored at a temperature of -18 °C or lower.

Tips

  • Transport: Transport frozen products in cool bags or containers so that the cold chain is not interrupted. Observe the instructions on the product packaging regarding storage temperature and shelf life.
  • Freezing: Allow prepared food to cool before freezing so that no condensation forms in the freezer compartment. This would freeze and form large ice crystals on the food.
  • Defrosting: Food should be defrosted in airtight containers in the refrigerator. Carefully remove defrost water and clean used kitchen utensils - knives, chopping boards and also hands - well with detergent or soap and hot water.
  • Re-freezing: If too much raw meat/fish has been thawed, always cook thoroughly before freezing again (at least 70 °C for 2 minutes in the core of the food). This is the only way to ensure that all germs are killed.
  • Freezing containers: For freezing in the household, use only materials suitable for freezing. These are freezer bags, plastic films or stackable plastic boxes with a tightly closing lid. Packing and parchment paper, plastic carrier bags or garbage bags as well as yoghurt or margarine cups and glasses that can break or splinter are unsuitable.

Defrosting and Preparation

Defrosting and Preparation

  • Do not thaw frozen food at room temperature, but in the refrigerator. Always use tightly closing containers for raw meat and fish. This prevents bacteria from being transferred via dripping meat juice to foods that are no longer heated before consumption (e.g. fruits, salads).
  • Washing hands regularly before preparing food, immediately after handling poultry or other raw foods of animal origin and after going to the toilet is an important measure to protect against pathogens. Fruit, vegetables and salads should also be thoroughly washed before consumption. Be sure to use clean towels to dry your hands.
    -Meat and raw vegetables must be prepared in the kitchen using separate kitchen utensils (e.g. cooking spoon, chopping board, knife) on different work surfaces or at different times.
  • After handling raw poultry, hands, knives and chopping boards should be washed with hot water before carrying out any other kitchen work. Otherwise the germs could be transferred to other foods that are no longer heated, such as salads, ready cooked foods, sauces. The order of preparation can also prevent cross-contamination from the outset if, for example, raw poultry meat is only processed after salad washing.
  • Sufficient heating is a safe method to kill pathogens. Food, especially meat, poultry, eggs or pasta with cream filling, should be boiled well or cooked thoroughly. Most pathogens are killed by heating to over 70 °C for 2 minutes in the core of the food. If, when cutting meat, the meat juice is clear and not pink; if in doubt, check the temperature with a meat thermometer.
  • Food already prepared should be cooled rapidly and not stored for several hours at room temperature. It is best to store them in the refrigerator after cooling. To speed up the cooling process, food can be divided into smaller portions and placed in a cold water bath. If you want to keep heated food warm until it is eaten, you should keep it at a temperature of over 70°C.

Food Irradiation

Food irradiation is a physical preservation process by treatment with ionising radiation. Electrons or gamma radiation from the radioactive decay of cobalt-60 are typically used as ionizing radiation. However, irradiation does not make the food radioactive.

Treatment with ionizing radiation kills microorganisms and delays maturation and germination processes, thus prolonging shelf life.

Food irradiation is a physical preservation process by treatment with ionising radiation. Electrons or gamma radiation from the radioactive decay of cobalt-60 are typically used as ionizing radiation. However, irradiation does not make the food radioactive.

Treatment with ionizing radiation kills microorganisms and delays maturation and germination processes, thus prolonging shelf life.

Current research results

Focus action 2017: Control of exotic seasonings and dried herbs for treatment with ionising Radiation (German)

In 2016, more than 100 samples were tested with a focus on teas, dietary supplements (NEM) and dried mushrooms. The graph below shows in detail which and how many samples have been tested with which methods. Of a total of 112 samples, no irradiation could be detected in a single sample.

 

 

Legal Regulations

Legal Regulations

The legal basis of food irradiation in Austria is regulated in §9 LMSVG. Accordingly, it is forbidden to treat foodstuffs with ionising radiation or to place them on the market without authorisation. At EU level, food irradiation is regulated in the Framework Directive 1999/2/EC (which defines labelling, among other things) and in the Implementing Directive 1999/3/EC (which contains the list of products authorised for irradiation throughout the EU). Currently, only dried aromatic herbs and spices may be irradiated in Austria on the basis of the EU Directive 1999/3/EC. There are no further national approvals, while in other countries a number of foodstuffs may be irradiated. Irradiated foodstuffs must be labelled with the words "irradiated" or "treated with ionising radiation".

Link to the EU legal framework: Legislation Food Irradiation

 

 

Detection Methods

Detection Methods

Evidence of food irradiation is based either on "frozen" excited charge states or on radical species arising during irradiation or their derivatives. The various analytical methods are briefly described below.

Luminescence measurements

These processes are based on charge carriers excited by irradiation in mineral impurities in food, e.g. earth traces. The energy supply (heat or light) causes the charge carriers to return to the ground state. The resulting luminescence is measured. These include photostimulated luminescence (PSL), which is a rapid screening method, and the more complex thermoluminescence (TL), which is used as a safeguard. Applications are e.g. spices and teas.

Electron spin resonance (ESR) spectroscopy

During irradiation, stable radicals are formed in crystalline structures (bones, shells, etc. in animal products or crystalline cellulose and sugar in plant products). These absorb microwave radiation in a magnetic field.
With this procedure poultry, lamb, fish and shellfish, nuts, berries, etc. are examined.

Gas Chromatography Mass Spectrometry (GC-MS) of Fat-Radiolysis Products

In fatty foods, the radicals produced during irradiation lead to the formation of 2-alkylcyclobutanones, which are radiation-specific marker substances and can be detected by GC-MS analysis. This method is used, for example, for meat and fish samples.

 

 

Examinations

Examinations

The Group "Contamination and Special Analytics" is Austria’s sole institute conducting routine examinations on food irradiation. It uses a variety of special equipment enabling it to apply all the methods mentioned above.

Official food inspections test a variety of foods, such as spices, herbal tea, instant soup, poultry, fish, shellfish and crustaceans, etc. to determine whether irradiated herbs or spices have been labelled properly or whether other foods have been illegally treated using irradiation.
We also offer services in the field of special analytics to private clients from production and retail, as well as to other laboratories.


Contact

Dr. Christoph Czerwenka
Phone: +43 50 555-32531
Spargelfeldstraße 191
1220 Wien



Dr. Christoph Czerwenka
Phone: +43 50 555-32531
Spargelfeldstraße 191
1220 Wien



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