Food hygiene is too important to neglect. If food isn't preserved and stored properly it can not only loose its nutritional value, but it can acquire unwelcome visitors - molds, microorganisms, insects, and so on. The Swiss Association for Nutrition has valuable information on the best ways to store and preserve your food.

Food - the sustainer of life

Our existence is based on the availability of sufficient good-quality nutrition and drinking water. In pre-industrial times, famine recurred repeatedly everywhere, and the management of food and potable water continues to remain a critical problem in developing countries. Negligent handling of foodstuffs and drinking water can result in malnourishment and disease. Food is therefore a valuable asset in every respect.

Mankind has responded by developing preservation methods and improving them tirelessly. There are two sides to food preservation. On the one hand, it addresses food safety in terms of contamination by microorganisms, and on the other, it addresses preserving quality, i.e., nutritional value, digestibility, and sensory properties (appearance, color, smell, taste, etc.). Manufacturers are responsible for the safety of production, packing, transportation, and storage methods. The consumer bears some responsibility too - for shopping, correct storage, and preparation of a food product. Compliance with the following guidelines is therefore imperative.

Why we protect food and drinking water

The quality of food and drinking water has a direct effect on our health. If food spoils, macro- and micro-nutrients are destroyed or altered so that dangerous contamination occurs. Heavy infestation of food or water with microorganisms leads to acute illnesses and epidemics, or even to chronic diseases. The most important food or water-borne pathogens are:

• Bacteria (e.g. salmonella, cholera, tuberculosis);
• Viruses (e.g. hepatitis A, K viruses);
• Mold (these can produce poisonous residues, called mycotoxins);
• Parasites, especially worms (these can entrench themselves in the human gastrointestinal tract and cause illness).

Food that contacts insects or rodents can likewise become a source of disease.To prevent such contamination, food and drinking water must be treated or preserved. Proper transportation, appropriate storage, and hygienic preparation are essential for food safety.

How foodstuffs are preserved

At first, people simply used whatever nature provided to preserve foodstuffs. Over time, methods such as drying in the sun or wind, smoking over a fire, or chilling in the snow were discovered. Then, with advances in technology, more promising procedures such as sterilization, freezing, and freeze-drying came into use. All serve the goal of limiting, suppressing, or preventing the development of microorganisms.

Preservation through drying

In this procedure water, which is essential for the survival of bacteria, molds, and yeasts, is removed from the foodstuffs.

Air Drying
Water is removed from the tissue through air drying, drying in the sun, or by industrial methods (warm air flow). Examples: cereals, green beans, figs, pepper pods, biscuits, cookies.

Drum Drying
In this technique, water is removed from foodstuffs by placing them over a heated drum. Examples: potato flakes, milk powder.

Freeze Drying
The food for drying is chilled to freeze the water content. The ice that forms is removed in a vacuum. In this procedure, taste and nutritional content of the product are not affected. Examples: freeze-dried coffee, mushrooms.

Smoking
The food is exposed to smoke from a wood fire. This method is often combined with drying and salting. The smoking process produces substances that counteract the development of microorganisms, while oxidation of fats is retarded and rancidity is prevented. Examples: smoked ham, fish, bacon.

Preservation by additions to the food

Bacterial proliferation is prevented by adding specific substances to the foodstuffs.

Salting or pickling
In this procedure, foodstuffs are treated with sodium chloride (salt) or pickling salt (a sodium chloride/sodium nitrite mixture), which makes the water content unavailable.Examples: anchovies, salt herring, sausage products.

Acidification
Most microbes cannot proliferate in an acid environment. Food can therefore be protected from spoiling by products that elevate the degree of acidity. Examples: vegetables stored in vinegar, yogurt.

Preservation with sugar (sugaring)
Microorganisms develop very slowly in sugar-rich products because of the absence of water. Examples: pastries, fruit pies, fruit sauces, candied fruits.

Cold preservation

Bacteria are not destroyed at very low temperatures, but their proliferation is limited.

Refrigerating
Refrigeration occurs at temperatures between -1°C and +8°C. Reactions leading to food spoiling are slowed down under this method, and microbial proliferation is reduced. However, shelf-life is not unlimited at this temperature. Examples: fresh products (milk products, meat, eggs, vegetables), cooked food.

Freezing
Food is gradually cooled to -18°C to -20°C in this procedure. Microbial proliferation is halted at this temperature. Large ice crystals are formed in the central areas of the products during the freezing process and possibly affect the cell structure, which causes some degradation in appearance and taste. Examples: fish, meat, vegetables.

Deep Freezing
This term applies to the industrial freezing method. The temperature of the foodstuff core is lowered as quickly as possible to at least -18°C. This changes the water into small, evenly distributed crystals that do not alter the product's structure. Its nutritional value is identical to that of fresh products, since these foods are deep frozen immediately after harvesting. Nutrients, vitamins, and other properties are largely preserved. Deep frozen products do not contain any preservatives. Nearly all foods can be deep frozen, thereby allowing a wide selection to be offered. This method can also be used for items from the home garden or for leftovers.

Vegetables must usually be blanched, that is precooked in boiling water or steamed. The reason is that at harvesting, they still contain several enzymes that remain active even at very low temperatures and alter the color and taste. The enzymes can also accelerate the degradation of vitamins, especially of vitamin C. However, they are also heat-sensitive and lose their effect during blanching. Some types of vegetables can be frozen without treatment, such as Chinese cabbage, cucumbers, carrots, green leeks for soup, peppers, celery sticks, tomatoes (for cooking), Jerusalem artichokes, and cooking herbs (parsley, basil, mints, chives). Examples: vegetables, ice cream, ready-to-use dishes.

Preservation through heat treatment

Pasteurization
Foodstuffs are exposed for a few seconds to a temperature less than 100°C and then rapidly cooled. Pathogens are thereby destroyed, and the number of microbes harmful to preservation is reduced in number. The product is thereby temporarily stabilized. Nutritional quality does not change. Examples: milk, fruit portions, partially-preserved foods (goose or duck liver pâté, meat in preserving jars, anchovy filets).

Sterilization or ultra-pasteurization
With this method the product is enclosed in a thick container (glass bottles or jars, metal cans) and subjected to heat treatment at a temperature above 100°C. This assures complete destruction of enzymes, microorganisms and their toxins. No more minerals are lost than in home cooking. For milk, a UHT process (ultra high temperature) is used. Taste and nutrients are better protected in this treatment (140°-150°C for 1-2 seconds). Examples: preserves, ultra-pasteurized milk, canned soups.

Preservation using food additives - "preservatives"

Specific additives are used to obtain longer shelf-life. They delay or prevent the impact on food of microorganisms that alter taste or appearance. Examples: light jellies, baked goods, sausage products, dried fruit.

Preservation by ionizing radiation

Ionization
No heating is involved in this type of sterilization. It prevents microbial development and destroys insects, some parasites, and bacteria through ionizing radiation. The shelf-life of very easily spoiled foods is extended since aging or rotting are slowed down. Authorization has not yet been granted in Switzerland for the irradiation of any foodstuffs. Examples: cereals, fruit, vegetables, spices, cooking herbs, potatoes.

Tips for food shopping

• Pay attention to the expiration date: "Sell by..." and "Use by..."
• Do not buy any precooked items in packages that are damaged, torn, or open.
• Do not buy any damaged or dented cans of preserved food.
• Buy frozen foods last.
• Do not buy any item that is iced up or has been thawed.

Tips for food transportation

• Put meat and poultry in separate plastic bags and pack them in the shopping bag so that any leakage will not contact fresh consumable foodstuffs (e.g. fruit and vegetables).
• In the case of long trips to the store (more than an hour) or in the summer, use a cooler pack or ice chest to prevent elevations in temperature.

Tips for food storage

• When you get home, first store the frozen items immediately in the freezer (temperature at -18°C).
• Put perishable items in the refrigerator without delay.
• Always read the label: it contains information on proper storage location, temperature, and duration. The minimum storage life: "Good at least through...." ensures quality and preservation during this time. After that date, the product may still be used, but the taste may be inferior. The expiration date: "Use before ..." must be absolutely observed, since it is used for perishable goods such as meat, milk products, etc.

Storage in a cool location (cellar, food closet, pantry)

• The cool area (ideally below 18°C) should also be dark and have circulating air. Avoid using cupboards near a heat source (near or over the stove).
• Do not store cold-sensitive fruit and vegetables in the refrigerator. The taste, smell, and consistency may change. Store such fruits in a relatively cool environment (definitely not in the kitchen) in a basket. They will ripen after a few days.

• Transfer the contents of opened packages (e.g., cereals) to hermetically sealed containers made of glass or plastic.
• Regularly check the expiration dates, and renew supplies by using the oldest foods first (preserves, flour).
• Mark self-prepared foods with the date and contents (e.g., jellies).

Refrigerator storage guidelines

• Keep all perishable foods (fresh goods and partially preserved foods), partially used fruits and vegetables (watermelons, melons, cucumbers) in the refrigerator.
• Refrigerate all pasteurized and ultra-pasteurized products after opening.
• Seal cooked leftovers and store them in a cool place.
• Leave cheese in its wrapper or wrap it in plastic to keep it from drying out, and store it in a plastic container.
• Products kept too long in the refrigerator gradually lose their quality, but do not "go bad" or create a health hazard.

How to store food in the refrigerator

• Open the refrigerator door only briefly to keep the temperature inside constant. Don't overload the refrigerator; allow for air circulation and thereby prevent a rise in temperature.
• Foodstuffs must be correctly stored in the refrigerator:

How long food may be stored?

The following information is just a guideline. The storage life may vary, depending on temperature, moisture content, and quality of the food. In any case, always check the expiration date on the package.

Source

Schweizerische Vereinigung für Ernährung / The Swiss Association for Nutrition (SAN). Merkblätter zur Ernährung, Vol. II. Main Editor: Herr Hansjörg Ryser, Bern.Website at : http://www.sve.org/english/index.html

Links

• How To Reduce Your Risk of Foodborne Illness
• Easing the Effort of Food Preparation