Amid cooking and science: how does low-temperature cooking work?

Low-temperature, or sous vide, cooking is a slow cooking technique that requires a vacuum to be created using safe and professional machinery, in order to obtain high-quality results. With the sous vide method, the food is vacuum-sealed and immersed in a vat of water at a precise and controlled temperature to cook.

But what are the mechanisms involved, and why has this method become so popular? All the characteristics of the technique, as well as the tools needed and the tricks for using them, are briefly described below.

What is low temperature vacuum cooking?

As previously mentioned, sous vide cooking differs from traditional cooking techniques in three fundamental ways:

• temperature
• cooking time
• the use of vacuum

Sous vide cooking often takes longer than traditional cooking techniques, and is performed at lower temperatures. In order to be prepared safely, and achieve the desired texture and flavour, the food must be vacuum-sealed.

The combination of low temperatures and prolonged cooking times results in tasty entrées with a particularly tender and juicy texture, while the vacuum guarantees the safety of the food, and prevents the juices and flavours from escaping.

In addition to the high quality of the food prepared using this technique, sous vide appliances are also extremely reliable and easy to use, and guarantee precise, constant, and uniform temperatures, for a perfect cook every time.

Safety and quality: the fundamental role of vacuum cooking

The first step in any sous vide recipe is to vacuum seal the food to be prepared, using special bags that are also suitable for the cooking process. This is an essential step for two reasons: the quality of the dish, and consumer safety.

Using professional vacuum chamber machines it is possible to achieve a vacuum percentage of over 99%. The effectiveness of the machine and the quality of the bags is a determining factor, as the vacuum prevents bacterial growth and food deterioration during the cooking process. For some recipes, the cooking times can be up to 24 hours, as they are performed at much lower temperatures than traditional recipes. A 99% vacuum renders the food entirely safe, with no need for higher temperatures.

At the same time, the vacuum packed product is hermetically sealed, so none of the moisture or natural flavours are able to escape or evaporate. In fact, they are enhanced by the long cooking process and the low temperatures. The duration of the vacuum cooking process also has a positive effect on the food's consistency, especially that of meat, whose tough and stringy elements are greatly softened, even at the lowest cooking levels.

Sous vide recipes: temperatures, duration, and results

This low temperature slow cooking technique requires specific recipe books, which often differ considerably with respect to traditional recipes. Sirman, makes a recipe community available to its users free of charge via its App SRCS.

Most vacuum cooking recipes for meat dishes call for temperatures of 53°C to 72°C, with cooking times ranging from 30 minutes for small cuts to 24 hours for certain types of roast, and for more demanding meat varieties like pancetta. For fish, the temperatures and cooking times are both generally reduced, while vegetables require higher temperatures.

The great advantage offered by the sous vide technique, especially with meat, is the possibility of setting the temperature with absolute precision, thus always obtaining the exact level of cooking desired.

This is possible because professional sous vide machines have a very low delta value, so the set temperature won’t fluctuate by more than just a few tenths of a degree. Especially stick sous vide machines, or rather those consisting of an immersion thermocirculator, which ensure extremely precise and even heat distribution within the cooking vessel.

The vacuum cooking process results in tender, evenly cooked, and extremely flavourful entrées. Unlike with traditional cooking methods, the nutritional properties are better preserved, and no oxidation occurs. As a result, the colours remain bright, giving the dishes a healthy and appetising appearance.

In order to enhance their visual impact, and obtain an even more appealing exterior texture, more similar to that obtained through traditional cooking, food prepared by sous vide can also be briefly seared in a pan or grilled.