Principles and processes of food preservation

Food preservation is the process of handling food to prevent or reduce spoilage (reduce quality, reduce nutritional value) caused by bacteria. In addition, preserving food has the effect of preventing the growth of bacteria, fungi and other microorganisms, as well as preventing the oxidation of rancid fats. In addition, food preservation inhibits natural aging and discoloration that can occur during food processing such as enzymatic browning in apples after being cut. So how is the principle and process of food preservation done?

Fruits and vegetables are considered an important part of a healthy diet. The United States Department of Agriculture recommends that each person consume up to half of a healthy plate of fruits and vegetables. Adult women should eat about 1/2 to 2 cups of fruit and vegetables per day, and adult men should eat about 2 cups of fruit and 2.5 to 3 cups of vegetables. everyday. A diet rich in fruits and vegetables can help reduce a person's risk of many conditions, such as high blood pressure, heart disease, stroke, and some types of cancer. However, if these foods are not handled and stored properly, these fruits and vegetables themselves will become a source of foodborne illness. For example, each person can become infected with listeria, salmonella, or other bacteria. Besides, the taste, texture and appearance of foods can also be affected if they are not stored properly. That's why everyone should learn how to prepare clean food and preserve fruits and vegetables.
The following is the process and principles of food preservation:

Most of the food sources come from rural areas or farms, and are moved from many regions to sales locations. During the long journey, fruits and vegetables are very easy to be infiltrated by harmful bacteria or other contaminants on the way.
This is entirely possible with organic foods and without the use of pesticides, pesticides and conventional products. Even if these foods look appealing on the surface, there is a risk of contamination. Therefore, to avoid harmful contaminants to food, before processing foods, the products should be washed.

You also do not need to use additional detergent products such as soap or vegetable washes, simply using clean water can also clean food. In addition, cleaning tools such as brushes should not be used for other cleaning purposes. If there is wax coating on fruits and vegetables, wipe the coating off with a paper towel or cloth after being washed.
Although it is most important to wash produce before eating, it is best to store foods unwashed. The reason for this is that too much moisture can cause the vegetables to spoil quickly, or during the washing process, the vegetables can be crushed and become a risk for bacteria to enter. Therefore, only wash vegetables and fruits before processing them.

For food stored in the refrigerator, different fruits and vegetables should be stored in different ways. According to experts at the Cornell Cooperative Agricultural Extension Center, vegetables usually need one of the following four types of storage:
Cold storage (0 - 4 ° C) Cool moist storage (4 - 10 ° C) Storage cold storage (0 - 4°C) Warm dry storage (10 - 15°C) Generally, your refrigerator should be maintained at around 1°C. It's best to store vegetables in a cold storage area. dedicated to foods of plant origin. This section is usually arranged as a small drawer located at the bottom of most refrigerators. Today, modern refrigerators often have additional humidity control features suitable for each different type of food. Therefore, if possible, store vegetables at the temperature and humidity where they grow best.
Products best preserved in cold, moist storage include: apples, broccoli, carrots, lettuce, eggplant.
Products that are best preserved in cold, dry storage include: Garlic, onions.
Products that are best stored in warm, dry conditions include: Hot peppers, pumpkins, winter squash, sweet potatoes.
For safety reasons, you should refrigerate or freeze fruits or vegetables that have been washed and cut. Store washed and cut produce in a plastic bag or sealed container to ensure food freshness and limit exposure to air. Always store fruits and vegetables separately from raw meat and dairy products to avoid bacterial contamination.

2.1. Storing fruits and vegetables in the freezer Almost all fruits and vegetables can be stored in the freezer. Freezing can change the texture of many fruits and vegetables, but they generally retain their flavor, nutrients, and possible health benefits.
Storing in the freezer is a great way to stock up on seasonal fruits or vegetables for use at the end of the year, especially if housewives plan to use them to make smoothies or eat raw vegetables along with other dishes.
The most important thing is to store frozen fruits and vegetables in an airtight container. Avoid freezing unripe products. This can stop vegetables from ripening and they will still be green when removed. Green vegetables intended to be eaten raw, such as lettuce, should not be frozen.
2.2. Store vegetables and fruits in a cool, dry place There are a number of vegetables and fruits that scientists recommend not to be stored in the refrigerator, even the cooler or the freezer compartment. Instead, they should be stored in a cool, dry place. The list of fruits and vegetables that should not be stored in the refrigerator include: tomatoes, bananas, potatoes and lemons. In particular, tomatoes can lose flavor and nutrients if stored in the refrigerator. They can also degrade due to certain reactions occurring inside the tomato fruit under cold conditions.
Fruits also usually don't need to be refrigerated. However, refrigeration will slow down their ripening process. Refrigeration can help them stay fresh longer. After washing and slicing fruit, you should store it in the refrigerator or freezer.

Food preservatives play an important role in preventing food spoilage, protecting from spoilage caused by mold, yeast, life-threatening food poisoning. Food preservatives reduce food costs, improve convenience, extend shelf life and reduce food waste.
There are two modes of preservation: physical and chemical. Physical preservation refers to processes such as refrigeration or drying. Chemical preservation is the addition of chemical ingredients to food for the purpose of preventing potential spoilage due to oxidation, rancidity, microbial growth or other undesirable changes - and considered as “direct additive”.

The US Food and Drug Administration classifies both natural preservatives (e.g., from lemon juice, salt, and sugar) and artificial preservatives as “chemical preservatives”. While many common preservatives occur naturally, manufacturers often use synthetic versions of these chemicals. Artificial preservatives can be divided into three main groups:
Antimicrobial agents that kill bacteria or inhibit the growth of mold on food: Benzoates - salts of benzoic acid Sorbates - sorbic acid and three mineral salts its, potassium sorbate, calcium sorbate and sodium sorbate Propionates - salts of propionic acid Nitrite - salts of nitrogenous acids Antioxidants that inhibit oxidation: Sulfites - a group of compounds containing the charged molecules of sulfur in combination with oxygen, including sodium sulfite, sodium bisulfite, sodium metabisulfite, potassium bisulfite and potassium metabisulfite Vitamin E (tocopherol) - a fat-soluble vitamin Vitamin C (ascorbic acid) - a vitamin soluble in water and salt Its components, sodium ascorbate, calcium ascorbate and potassium ascorbate Butylated hydroxyanisole (BHA) - waxy solid used to preserve butter, lard, meat and other foods Butylated hydroxytoluene (BHT) - are structurally and functionally similar Similar to BHA, but in powder form Conjugated chelators t metal ions in certain foods to prevent oxidation: Disodium ethylenediaminetetraacetic acid (EDTA) - used in food processing to bind manganese, cobalt, iron or copper polyphosphates ions - is used Used as an anti-browning agent in dips and rinses of peeled fruit and vegetables Citric acid - found naturally in citrus fruits All preservatives added to food products must be declared in the ingredient list on food labels using the generic names of the ingredients. In the absence of such a name, synthetic forms may be listed. For example, synthetic vitamin B9 might be listed as "folic acid". Preservative ingredients must be identified as a preservative or must have a specific function, such as “sorbic acid (to preserve freshness).”

Food preservation is the process of preserving as well as preventing food from decomposing leading to rancidity. Since ancient times, many methods of food preservation have been discovered by humans, however, preserving food by refrigeration is showing outstanding advantages compared to other ways of preserving food. Depending on the type of food, the refrigerator can preserve them for a certain period of time, from a few days to even years of food if kept in the freezer.
Any questions that need to be answered by a specialist doctor as well as customers wishing to be examined and treated at Vinmec International General Hospital, please register for an online examination on the Website for the best service.

References: britannica.com, healthline.com, brainkart.com, foodandnutrition.org