Long live the food!
Nowadays, when ~2.5 billion tons of food is wasted, food preservation is especially important. It provides access to off-season fruits and vegetables. Thanks to different methods of preservation we have the opportunity to try cuisines from different parts of the world. Food preservation includes growing, harvesting, processing, packaging, and distribution. The main disadvantage is that different preservation techniques may cause the reduction of some vitamins and other nutritional values.
How long can we store food without any preservation process? Based on shelf life, we can define 3 categories of food:
- Perishable – these last several days to about three weeks: milk and dairy products, poultry, eggs, seafood
- Semi-perishable – under good storage conditions they can be preserved for up to six months: vegetables, fruits, cheeses
- Non-perishable – can be stored for years: dry beans, flour, sugar, nuts, canned fruits
The use of certain means can significantly extend the shelf life of food. The most popular processes we can use are:
Known to the early Egyptians, pickling is a process of preserving food in an acid solution, usually vinegar, or in a salt solution (brine). This process can be chemical or based on fermentation. Vegetables and fish are usually pickled raw while meats need to be fully cooked. Fermented foods have been shown to have anticancer benefits. What is more, while cooking can break down heat-sensitive nutrients, including antioxidants, pickling raw vegetables and fruits preserves their antioxidant power.
Salting and sugaring
Both salt and sugar stop bacterial growth by removing moisture. Unfortunately, these methods can lead to the overconsumption of both substances.
Invented by Nicholas Appert in the early 1800s to feed Napoleon’s soldiers. This process preserves food by removing oxygen and closing the product in an environment where bacteria cannot thrive – acid, sugar, or salt.
A method named after Louis Pasteur, a French scientist known as the father of microbiology. The process includes heating food up to a specific temperature to destroy spoilage-causing microorganisms and enzymes, and, after that, placing the product into a sterile container. There are some nutrition losses, but not that significant.
Drying is one of the oldest methods of food preservation, and perhaps the cheapest. Using sun and wind, or modern dryers like shelf dryers or bed dryers, you can reduce water activity, preventing bacterial growth. Most microorganisms can grow at water activity above 0.95; bacteria – above 0.9. A good method for meat, fruit, or fungi. Reducing the weight and volume of foods makes them easier to carry and store. It also retains smells and flavors quite well.
Another ancient method – exposing fish or meat to wood smoke helps it last longer thanks to its antimicrobial and antioxidant properties. Temperatures of this process vary from 109 to 160 °F (43 to 71 °C), and smoking periods vary from as short as a few hours to as long as several days, depending on the type of food. Smoked food, however, shouldn’t be eaten too often because of stomach cancer risk.
Freezing and chilling
Freezing converts the water present in the food into ice. However, unlike water, most food doesn’t freeze at 0, but between 0 and -5. Bacteria cannot grow where there is no liquid water. However, some nutrients begin to break down when frozen produce is stored for more than a year. Chilling retards the growth of microorganisms and it is short-term but allows for the preservation of nutritional values well.
Which method works best for you? Planning how to store and preserve your food in advance may help reduce the amount of wasted food!
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