Think that when you were living in ancient society, in the hunting age there were no freezers to keep your foods in save as you do now. So you have to hunt every day to avoid eating spoiled foods. In that case, we have to use methods of preserving foods.
What is Food Preservation
Preserving foods is a process that prevents them from spoiling. It prevents the growth of bacteria and fungus which spoil foods.
History of Food Preservation
Food preservation is an action that has been done since in the past. There are numerous ancient methods of preserving foods. Burial, Jugging,Pickling and sugaring are few of them.
Methods of Preserving Foods
In the present, we use some Successful traditional methods and some newly oriented methods to preserve our foods. Here we have some discussion about methods of preserving foods.
This is a good method that preserves our foods for a long time. It is a process of reducing the temperature of a product to a particular storage temperature. It reduces growth and reproduction as well as the actions of enzymes.
Categorize of cooling foods
- Temperature range from -1 to 1 C is for fleshy foods like meat and marine products, poultry products etc.
- It goes the range from o to 5 C for dairy products like milk, butter, yoghurt, and foods like pasta goods, soup mixes, baked products like bread, pastries, pizza, etc.
- Temperatures range from 0 to 8 C for completely cooked fleshy foods such as meat, poultry and fish products as well as fresh fruits and vegetables.
- When determining a temperature range for fresh crops, it depends on various aspects. The main factor is the age of the crop and the nature of the edible part of the crop.
In the time of the first year of the Napoleonic Wars, the French government offered a cash award of 12000 francs for an inventor of a cheap and effective method of preserving a large number of foods. In 1809, Nicolas Appert could do that and the method was named as Canning.
There are two method of canning
1.Water Bath Canning
This boiling bath canning is a shorter, lower temperature process that is for high acid foods. The high acidity of the foods kills bacteria, allowing for the water bath method. We have to place six inches of water in the canner for hot packed jars, the water should be simmering at 180F for a row or cold packed jars, the water should be heated to 140 C. The water should rise to one to two inches above the tops of the jars more hot or boiling water can be added if necessary. Begin timing when water is at a full boil. After processing time, turn off canner, remove the lid and wait five minutes before removing jars. Check seals remove rings, store jars in a cool, dry, dark place.
Advantages and Disadvantages of Water Bath Canning
This is the best method for beginners to learn and the best method for fruits and high acid and pickled foods. It is also inexpensive to start. But the temperature does not get high enough to ensure the destruction of microorganisms in foods.
2. Pressure Canning
You know Pressure canning heats the foods to 240 F, eliminating the risk of foodborne bacteria. This method is used for low acid foods like many vegetables, meats, poultry and seafood products. A mixture of high acid foods and low acid foods can be preserved for a longer period with the pressure canning method. We have to place two to three inches of water simmering or hot in a canner.
Place jars on rack in canner. Put the lid on the canner with a weight off petcock open. Allow a steady stream of steam to escape for 10 minutes. Close vent or petcock. Count time when the correct pressure is reached. Turn off the heat at the end of processing time and let pressure drop to zero. Wait two minutes after pressure is at zero. Remove weight or petcock and wait ten minutes. open canner and remove jars. Cool the jars 12 to 24 hours. Check that jars are sealed.
Advantages and Disadvantages of Pressure Canning
This is the best method for low acid foods such as vegetables. This process reaches a higher temperature and completes in a short time period. But this method is more expensive than the water bath method. Some soft fruits may be damaged because of the high heat.
3. Burial of Foods
Burying foods is another good method of preserving foods. When you bury some foods, lack of light, lack of oxygen, cool temperatures and considerable ph levels are some of the factors that help you to preserve your foods. A salty and dry area can preserve many foods so that the burial method can be used with a combination of some several other techniques such as salting or fermentation.
Many things, such as edible roots of vegetables, prefer most for a dark, cool place. In such cases, we can bury them and preserve. Placing eggs in an alkaline mud is a traditional method that is used to preserve eggs for a number of centuries. So that they are called century eggs. Heat can kill pathogens, so foods like meat can be buried in hot coals or ashes. In northern US farms, they bury cabbage during Autumn for preservation. Another thing about burying is, if you bury something where the earth is very cold, the earth acts like a refrigerator.
4. Irradiation of Foods.
Approximately 550,000 tons of food items are irradiated per year worldwide in over 40 countries. This is a process of exposing foods to multiple types of ionizing radiations such as beta particles and gamma rays. Irradiation can kill most of the bacterias, molds, and insect pests, reducing the ripening and spoiling of fruits. Sometimes this method is called “cold pasteurization” because the foods do not get heated.
There were so many doubts with customers about irradiated foods. The major thing is based on micro concepts such as radio activation of foods. But organizations in the US such as the World Health Organization and Food and Agriculture Organization have endorsed food irradiation. Although in some cases, irradiation may allow low quality and contaminated foods.
5. Modified Atmosphere
It is a process of preserving foods by controlling and changing the atmosphere around it. Salad crops are heavily difficult to preserve. We can preserve them by modifying the atmosphere around it. You have to reduce the oxygen concentration and increase the carbon dioxide concentration in the air. Though salad vegetables retain their colour and textures in this condition, some of the nutritious factors such as vitamins may not retain.
There are two methods of preserving foods like grains by modifying the atmosphere around it. One is placing a dry ice block in the bottom and filling the can with the grain. It controls the humidity and preserves the grain. Another method is cleaning the bottom of the container with a bulk supply method of carbon dioxide gas. Carbon dioxide prevents the insects, mold and oxidation from damaging the grain you put in.
We can also use nitrogen gas for this purpose. In the air where nitrogen concentration at 98% or higher, can also kill the insects and other harmful factors. But killing carbon dioxide has a better ability than nitrogen. The case is, if you want to preserve foods with carbon dioxide you have to place carbon dioxide concentration at about 35%. It is very difficult.
6. Drying Foods and Vegetables.
This is an old and environmentally-friendly method of preserving foods, that is mostly done in summer. For a long time, since ancient people have been using sunlight for their drying process. Nutritional values and Inherent flavour will be remaining at a higher percentage if you can use solar power for your drying process.
As fruits have a higher sugar level and a higher acid concentration, they may spoil soon. So you can dry them and preserve. the common steps are,
- slice your fruit into some slices.
- soak them in lemon juice approximately for five minutes.
- Dry them in an area where the temperature is higher than 85 degrees Fahrenheit.
- Make sure to be contacted with them to prevent moisture.
- Place your fried things in a jar for seven to ten days. Shake it for moisture controls
- Then place them in an oven at 160 degrees Fahrenheit or in a freezer at 0 degrees for 48 hours.
7. Pickling the Foods
This is a process of preserving foods that have been doing for a long time ago. Pickling process mainly affects the texture and the taste of the food. Vegetables, Fruits, Meats, dairy products and eggs are some of the foods we can pickle. Here is a common way of a pickling cucumber that can be used with many fruits and vegetables.
First, wash and slice your cucumber into small pieces. Then put them in a pot and add a certain amount of salt on it for moisture control. Then add it 2 cups of vinegar, 1 cup of cider vinegar, 4 and a half cups of sugar, 1/3 cup pickling salt, spice, onion, garlic. Fill a water canner 2/3 of it and start heating it. Add your cucumber mixture into several jars and clean the jar rims. Then seal the jars with jar lids. Keep them in that hot water carefully. Place the timer for several minutes when the water comes to a boiling temperature. When the time comes, get the jars and put them on a cooling rack for 12 to 24 hours.
Future of Preserving Foods.
The main technique that is developing for food preservation is the High-Pressure Processing method. Dr V.M. Balasubramaniam, a food engineer from Ohio State University is developing this method to use in future. They use water or hydraulic liquid for pressing the foods. This may be a perfect method because in these methods no chemicals are used. We may have the ability to use this method soon.