SCALDING FOOD: PROCESS, TYPES, ADVANTAGES, DISADVANTAGES - NUTRITION - 2025

The blanching of food is a process by which the vegetable or animal piece is cooked in hot water at a temperature between 85 and 98 ° C. The techniques of exposing food to live steam, controlling its temperature and cooking time, or to a chemical process are also used.

It is generally used as a preliminary step to a certain type of food preservation process (ie dehydration, lyophilization, freezing or sterilization) or also to prepare it for washing or peeling. In this way the enzymes that are normally present in food are inhibited.

This cooking technique is commonly used in the food industry and in domestic culinary work. It is different from poaching, because in this the water or liquid used to submerge the food does not come to boil.

Generally, blanching time ranges from 30 seconds to 3 minutes. It will depend on the type of fruit or vegetable treated, the size, the blanching temperature and the heating system used.

Process

The blanching process of food is carried out in phases. The water must first be heated to a temperature that can vary between 70 ℃ to 100 ℃.

Then the treated food (tomato, broccoli, corn, pork, poultry) is kept submerged for a certain time. It can vary between 30 seconds and 2 or 3 minutes, depending on the objective, at the required temperature.

Later it proceeds to its rapid cooling. It is extremely important to do this step with the greatest care and in the shortest time possible, because there is a risk that the food will be contaminated with thermophilic bacteria, which are resistant to any temperature.

For an adequate enzymatic inactivation it is necessary to produce rapid heating until the desired temperature is achieved; then keep the temperature constant for the required time. Finally, rapid cooling is carried out to a temperature level similar to that of the environment.

The enzymes that produce the degradation process of food and that are neutralized with scalding are catalases, lipoxygenases and peroxidases. These enzymes are present in the skin of food.

Types

There are different domestic and industrial methods for treating food with blanching. The most important ones are mentioned below:

Scalding with hot water

It is the most used and common. It consists of immersing the piece or food in hot water until reaching the ideal point for its conservation or peeling. The advantages of this method are its efficiency, the control over the process and the uniformity that is achieved.

The disadvantages are that a significant volume of water is required. In addition, it produces a process of leaching or loss of acids, minerals and vitamins in food. On the other hand, large amounts of wastewater are generated that contain a high percentage of organic matter.

Steam blanching

It consists of a very intense local heating of the food surface; This causes the weakening or disorganization of the tissues. In this way, the skin is more easily detached from the food, because the steam at a high temperature causes its decompression.

There are industrial steam blanchers that consist of a wire mesh belt, which transport the food through a chamber or tunnel that injects steam. Other more modern and efficient blanchers are closed chambers where the food is introduced and, after a while, the piece is scalded.

Steam blanching offers the advantage that it causes less carry-over of nutrients and solutes from vegetables (corn, broccoli, peas).

The disadvantage is that in the artisanal or domestic process the enzymatic inactivation requires more time. Food can be damaged, and time and temperature are more difficult to control.

Chemical scalding

Because hot water and steam blanching methods damage some products such as strawberries, figs, etc.

Then blanching is used by applying a chemical compound. It consists of immersing food in a solution of ascorbic acid, sulfur dioxide, sulfites, bisulfites or meta bisulfites.

The advantage of this method is that it minimizes the oxidation of food and prolongs its preservation by preventing microbial growth. The downside to this method is that it can cause allergies in some people.

Microwave blanching

The food industry uses this method to treat some foods such as corn, potatoes and fruits.

So far it is unknown that there are commercial applications of this method. Its effects are not easy to quantify either, unlike those of hot water and steam blanching.

It is considered a clean technology for the processing of foods such as chard, artichokes, thistles, borage and beans. Microwave blanching is used in the preparation of vegetable preserves, which saves a lot of water and energy.

Scalding with hot gas

This method consists of heating the vegetables using a mixture of steam and gases that come from natural gas burners.

Its main advantage is that it reduces the amount of effluent or residual liquid. The downside is its poor performance; for this reason it is not used commercially.

Other experimental methods

In addition to the traditional and well-known methods of blanching food, there are other processes. There are canned blanching, vacuum blanching, and combined vacuum and steam blanching.

Advantage

- Partially reduces the presence of bacteria in food when it is cleaned, dried or frozen.

- Inhibits the enzymatic action.

- Softens the skin of food to be peeled.

- Improves handling and packaging of products.

- Prevents corrosion and prolongs the preservation of food.

- Helps to fix and accentuate the natural color of food by removing impurities from the surface.

- Removes undesirable flavors and odors.

- Eliminates fat in food making it more digestible.

Disadvantages

- Reduces the nutrients of some foods (vitamins and minerals), reducing their nutritional value.

- Depending on the type of scalding, a high volume of water is often required.

- Generates large amounts of wastewater containing a high level of polluting organic matter.

- There is a risk of contamination with thermophilic microorganisms present in the scalding tanks.

- May cause weight loss in products.

References

1. Blanching of food for greater safety. Retrieved May 22, 2018 from consumer.es
2. Steam blanched. Consulted of knowledgeweb.net
3. Peñuela Teruel, María José: Influence of cooking and preservation processes on the content of nitrates and nitrites in spinach (Spinacia oleracea L.). UCM Doctoral Thesis. Recovered from library.ucm.es.
4. Scalding. Consulted of sciencedirect.com
5. Scalding. Consulted from britannica.com
6. Scald. Consulted from geniuskitchen.com
7. Scald. Consulted of cooksinfo.com
8. Blanching with microwave for canned vegetables (PDF) Recovered from alimentatec.com