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Food preservation refers to any technique that prevents food from spoiling. It inhibits the growth of micro-organisms such as yeasts, as well as stopping rancidity, by slowing down the oxidation of fats. The preservation of food items can be done through traditional methods or modern techniques.
Traditional Methods of Food Preservation
- Boiling: this is the process of boiling liquid food items, to kill any existing harmful microbes present.
- Curing: this method has been used from as early as 12,000 BC, where food items are dehydrated or dried. Salting and smoking were introduced to improve the process, as they add antimicrobial agents that help preservation. Salt speeds up the drying process through osmosis, while smoke deposits pyrolysis products onto the food. Nitrates are also used in the curing of meat, giving it a pink colour.
- Freezing: this is a very popular method of preserving food, both in the home and commercially. It is used to preserve a wide variety of food, including prepared food that would not have required freezing, in their unprepared state.
- Heating: this is the process of heating food, to temperatures sufficient enough, to kill microorganisms present in the food. Milk is one food preserved this way.
- Cooling: food preservation is done under this method, by hampering the growth and reproduction of microorganisms. The introduction of refrigerators led to a drastic improvement in the dietary habits of a lot of people, as food items such as dairy, meat and fruits could be stored for longer periods of time, especially during warm weather.
- Sugaring: sugar has been used as a preservative agent by early cultures, as it was normal for fruits to be stored in honey. Heating food to be stored with sugar is a common practice in cooler r climate, where there is insufficient sunlight to dry food.
- Lye: when sodium hydroxide (lye) is added to food, it increases its alkalinity thus, making it difficult for bacteria to grow. Saponification of fats in food by addition of lye, changes the texture and flavour of such food.
- Pickling: under this method, food is preserved in an edible microbial solution. There are two broad categories of pickling; fermentation picking and chemical pickling.
- Canning: food is preserved here by cooking, then sealing it in a sterilised can or jar. The containers are sterilised by boiling them, in order to kill any remaining bacteria. This process was invented by Nicolas Appert, a French confectioner.
- Jugging: this is the process of stewing meat in a casserole or an earthenware jug. The meat is cut into pieces, placed in a tightly sealed jug with gravy or brine, and then stewed. The blood of the animal or red wine can sometimes be added to the cooking liquid.
- Burial: the lack of light, pH level, lack of oxygen, desiccants in the soil and cool temperature, are all factors that preserve food, whenever it is buried. Burying of food to preserve it is commonly combined with other methods of preservation, such as fermentation or salting.
Modern Methods of Food Preservation
- Artificial Food Additives: these additives could be antioxidants, such as oxygen absorbers, which prevents the oxidation of food constituents, or antimicrobial, which hinders the growth of bacteria, fungi or mould.
- Pasteurisation: this method is applied in the preservation of liquid food like milk. Here, milk is heated to about 700C, for not more than 30 seconds, s to kill bacteria in it, and cooled quickly to 100C, to stop the growth of the remaining bacteria.
- Freeze Drying: this is also called Cryodesiccation. It is a process of dehydrating food in low temperature, by freezing the food, reducing pressure and removing ice by sublimation. This is different from other methods, where dehydration is achieved through heat.
- Vacuum Packing: here, food is stored in a vacuum, which could be an air tight bag or bottle. This way, bacteria present in the food are starved of oxygen, required for their growth. A major disadvantage of this method is loss of flavour and deformity.
- Irradiation: in this method, food is exposed to ionising radiation. Several types of ionising radiation can be used, including gamma rays and beta particles. This method kills insect pests, mould and bacteria. It reduces the ripening and spoiling of fruits.
- Modified Atmosphere: Here, the atmosphere around food items is altered, to preserve them. Crops such as salad crops, are preserved this way because of the difficulties in preserving them. They are packed in sealed bags, the oxygen concentration around them is reduced, and the carbon dioxide concentration around them is increased.
Refrigeration and Food Preservation
Preserving food in cold temperature has been in practice for long in human history, as far back as when caves were used, to preserve and keep food cold. In recent history, southern Europe was already practicing the cooling of drinks in the 1600’s, where bottles are rotated in a solution of water and potassium nitrate. The introduction of the refrigerator impacted greatly on food preservation. Agricultural output has increased, because produce can be preserved longer by refrigeration, it also made out of season food, available all year round. Refrigeration has affected our diet positively, as meat and fish can be stored for longer periods, and be consumed as often as preferred. Salads have also become a staple, because fruits and vegetables can be preserved by refrigeration.
Refrigeration preserves food by slowing down bacteria activities, which prevents them from multiplying, and eventually kills them.
Refrigerated Vans at Glacier Vehicles
The invention of the refrigerator has not only improved the preservation of food, but has also made inaccessible food accessible. Food are transported in refrigerated vans and trucks, to maintain their freshness.
At Glacier Vehicles, we understand the importance of our refrigerator vans performing up to industry standards. Our refrigerated vans are guaranteed to serve you, for years to come. We have a team of in-house engineers, who make sure every refrigerated van we sell is in order.