7 Ways To Preserve Food

7 ways to preserve food

By Dr Anny Manrich (PhD)

Page last updated: 02/04/2023 | Next review date: 02/04/2025

Author bio

Dr Anny March PhD is a food Engineer with expertise in Food Technology, Natural Polymers, Edible Films, Enzymes, and Nanotechnology.

Dr Anny Manrich’s Highlights:

Research and Technology at the Brazilian Agricultural Research Corporation

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Dr Anny Manrich (PhD)

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In this brief guide, we are going to answer the question “7 ways to preserve food” and discuss 7 ways to preserve food along with the benefits and implications of each method.

A major source of food waste in developed countries is the discarding by the consumer or food seller of foods that are perceived by the consumer to be relatively undesirable compared to other foods of similar consumption suitability, including foods close to, at, or beyond their ‘best-before’ date labels. In the United States, this confusion accounts for 20% of consumer food waste and leads U.S. consumers to spend $29 billion annually on wasted food. In Europe, it has been estimated that up to 8.8 million tons of food are wasted annually in the European Union due to date labeling (1).

7 common ways to preserve food are (2,3):

Freezing
Dehydrating
Pickling
Fermenting
Canning
Dry-salting
Curing and smoking

Preserving food by freezing

Freezing is the most widely used method of food preservation since it can be done easily at home by anyone and food is preserved for 3 to 12 months. Freezing is especially used for fruits, vegetables and meat products where the original taste and texture needs to be preserved.

Freezing food reduces the enzyme activity in food that causes spoilage. Freezing also crystallizes the water in the food so microorganisms cannot use it for growth. It reduces the amount of liquid water in the food items and diminishes water activity (2).

Freezing itself does not significantly reduce the nutrient content of food. However blanching before freezing and defrosting will cause the loss of some nutrients, mainly water-soluble nutrients such as vitamin C. Pre-blanching applications, such as peeling, trimming and ⁄ or slicing, can contribute to the negative effects of physical damage, which may lead to more leaching of vitamin C (4).

Preserving food by dehydrating

Dehydrating is one of the oldest methods of food preservation. Dehydrating works by removing the water from food, thereby reducing the growth of microbes that cause spoilage. Dehydrated food has a long shelf-life and can be stored for up to 5 years under the proper conditions.

Food has been dehydrated by natural sun-drying for ages. Now there are electric dehydrators which can be used at homes. Food can also be dehydrated using an oven or a microwave.

Drying has numerous advantages. It reduces weight and volume of foods, facilitates food storage, packaging, and transportation, and also provides different flavors and smells. With all these benefits, drying is apparently the cheapest method of food preservation. Significant loss of flavor and aroma has been observed after drying. Some functional compounds like vitamin C, thiamin, protein, and lipid are also lost because of drying (2).

Preserving food by pickling

Pickling is a method of preserving food by immersing in a solution of acidic brine or vinegar. Pickling adds a distinct flavour to food and pickles are used as side dishes and garnish in many cuisines.

Pickling is a type of preservation through fermentation. Fermentation method uses microorganisms to preserve food. This method involves decomposition of carbohydrates with the action of microorganisms and/or the enzymes. Vinegar fermentation takes place after alcohol fermentation. Acetobacter converts alcohol to acetic acid in the presence of excess oxygen (2).

Some commonly pickled fruits and vegetables include mangoes, cucumber, limes and radishes.

Pickles have a high content of sodium due to all the salt added for pickling. So eating large portions of pickles is not recommended. Pickles are also not recommended for people with hypertension and cardiovascular diseases due to the high sodium content (5).

Preserving food by fermentation

Fermentation is easily confused with pickling. The difference is that there is no addition of an acidic medium such as acidic brine or vinegar during fermentation. During fermentation, the carbohydrates in food are broken down into acids or alcohols by bacteria and yeast. Bacteria, yeasts, and molds are the most common groups of microorganisms involved in fermentation of a wide range of food items, such as dairy products, cereal-based foods, and meat products (2).

Fermentation preserves most of the nutrients and also produces probiotics. Probiotics are beneficial bacteria that help in maintaining gut health and improving immunity. Most probiotics fall into the group of organisms’ known as lactic acid-producing bacteria and are normally consumed in the form of yogurt, fermented milks or other fermented foods (6).

Some commonly fermented foods include cheese, yoghurt, sauerkraut, wine, beer and sourdough bread.

Preserving food by canning

Canning preserves food by killing the microorganisms that cause spoilage. Canning can be done at home using the correct equipment and proper sterilization of jars but it is time-consuming and needs practice. Thermal sterilization is a heat treatment process that completely destroys all the viable microorganisms (yeasts, molds, vegetative bacteria, and spore formers) resulting in a longer period of shelf life. Retorting and aseptic processing are two categories of thermal sterilization (2).

Canned foods are shelf-stable for years and do not need refrigeration until they are opened. However, the heating process during canning reduces the nutrient content of food, thus a severe heat treatment process at 135–140 °C and up to 150 °C are applied, which changes the properties of fats, protein, and sugar of food (2)

Canning is now done on a variety of commercial foods such as beans, corn, tomatoes, pineapple etc.

Preserving food by dry-salting

Dry-salting is simply the addition of salt to food. Dry-salting is related to pickling, but dry-salting can be done on foods without adding moisture by a brine or vinegar solution (3).

Salt is used as a preservative as it draws out water from the food thereby starving the microorganisms. Salt also kills some microbes by creating a pressure difference and rupturing their cell walls. Most bacteria cannot grow in an environment where the salt content is greater than 10%.

Dry-salting has the same disadvantages as pickling due to the high salt content used and must not be consumed in large portions. Dry-salting is mainly used in the fish and meat industry. Commonly dry-salted foods include beef jerky and salted dry fish.

Preserving food by curing and smoking

Smoking is a technique used to preserve food by dehydrating the food using smoke. Dehydrating and high temperatures will kill the microorganisms while smoke imparts a distinct flavour to the food (3).

Smoking food can be done at home and is also done on a large scale commercially. Fish and meat are among the most commonly smoked food products. The preservative effect is derived from reduced water activity (enhanced by salting) and the physical barrier represented by the dried fish surface combined with the antimicrobial and antioxidant properties of the phenolic compounds released in the wood smoke (3).

To preserve food for longer it is necessary to cure the food with salt before smoking. Cured and smoked meat can last for about a year. Cured and smoked meats have been linked to cancer in some studies so their consumption must be limited.

Conclusion

In this brief guide, we answered the question “7 ways to preserve food”. We discussed 7 methods of food preservation and looked at the benefits and implications of each method.

If you have any questions or comments, please let us know.