Vacuum cooking represents one of the most important technical innovations that have affected the professional catering business in the past few years.

Ingredients, even in a raw state, are stored in a resistant plastic bag, which can also hold preprocessed products like sauces, trimmings, and dressings.

The process is really quite simple.

The same machine that carries out the hermetic sealing of the pack at the end of the process, first creates an empty space in the bag in which foodstuffs can be placed.
Then, you proceed to cook the bag at a low and constant temperature ( from a minimum of 149 °F to a maximum of 208.4  °F ) in a steam cooker.
Once cooked, the product is refrigerated very quickly and kept at a temperature that does not exceed 37.4 °F.

Vacuum cooking presents many nutritious, qualitative, hygienic and economic advantages.
From a nutritional point of view, the low and constant cooking temperature allows for the minimization of changes in the vitamin content of the food.
In addition, the process of cooking the food inside a closed hermetic container avoids the loss of principle nutrients.
The organoleptic characteristics of food also benefit from vacuum cooking: you can obtain a concentration of juices that enhance the food’s natural tastes, thus allowing you to use fewer condiments, which then benefits digestibility.

The economic advantage of vacuums does not only include the possibility of organizing work in a more flexible manner, but also yields the same amount of product, subject to a weight loss decidedly lower than resulting from conventional techniques.

At last, hygienic benefits are not to be ignored.
First of all, the packaging in plastic bags protects the food from direct contact with external pollutant agents.
Secondly, cooking at a low temperature can be considered a method of pasteurization, able to guarantee the conservation of food in fully safe conditions.

The vacuum cooking process involves the use of a set of equipment: the machines to make the vacuum packaging, a steam cooker at variable temperature, an electronic probe for measuring the core temperature of the product, a refrigerator for the maintenance and storage of the products and a chiller.
Now, we should consider the characteristics of the first mentioned machines of this process: the vacuum packaging machines.

Vacuum packaging machines

Its job is to remove all the air (more than 99% of that present) from the casing that surrounds and contains a foodstuff: the operation is conducted by special “vacuum” machines.
Vacuum packing does not only apply to cooking processes, but can also be used for packaging raw foods that need to be stored awaiting processing, or to ensure that foods cooked in a traditional way keep before consumption.
The latter use resolves the problems surrounding the production of dishes for deferred service, specifically for catering banquets or large outdoor events.
In some cases, having to preserve raw, delicate foods or foods of fragile composition, the vacuum is able to be used to replace the extracted air with a shielding gas.
It creates therefore a sort of modified, inert atmosphere, which does not modify the form of the food.

These vacuum generating machines are divided into two types: those with external suction devices and those that are bell-shaped.

The first, characterized by their smaller size, suck the air directly out of the bag (vacuum bags, accordion-shaped, embossed) by means of a pump that can be a dry or lubricated.
Generally, external suction machines are made of stainless steel and in some models are extendable to ensure greater flexibility of use. Having a low weight and a particularly small size, they are ideal for storage in small places.
The bell-shaped machines instead look like a box whose lid is collapsible and is able to be made of steel or special plastic materials.
The food is placed in a clear plastic bag of polyvinylidene chloride that is inserted into the interior of the machine; the air intake is also ensured in this case by a pump, which sucks the air out of both the compartment of the machine and the bag container.
A heat sealing rod then provides the hermetic seal of the package.