Sous-vide, French for "under vacuum" was originally developed in France by Georges Pralus during the early 1970`s. The process evolved when Pralus and a food scientist joined forces to devise the perfect method for producing 'foie gras'.
Sous Vide is a professional method of cooking food sealed in airtight vacuum packed bags in a water bath for a long time — 72 hours is not unusual — at an accurately determined temperature much lower than normally used for cooking, typically around 60°C or 140°F. The intention is to maintain the integrity of the ingredients and achieve a very precise control of cooking. It differs from conventional cooking because the raw food is sealed in an oxygen free environment and the food is cooked using precisely controlled heating at a variation of only ±0.1°C.
From a culinary viewpoint the exclusion of air is secondary, but this has practical importance: it allows cooked food to be stored, still sealed and refrigerated, for considerable times, which is especially useful for the catering industry; and it excludes oxygen from food that requires long cooking and is susceptible to oxidation, e.g. fat on meat which may become rancid with prolonged exposure to air.
Sous Vide is a precision cooking technique which requires precise temperature control. This can only be achieved by using a water bath that allows exact thermal transfer of energy, stable temperatures and quick heat transfer into vacuum pouches. Precise cooking is especially important when cooking fish, meat and poultry. Consider the problem of cooking a 280g fillet steak to medium-rare. Cooking the steak on a grill at over 280° C until the centre comes up to 53° C will result in everything but the very centre being overcooked, but with the Sous Vide method of water bath cooking this is not a problem. The steak is poached in the pouch in a water bath at 54° C for 60 minutes and then seared in a hot pan to finish. The result is a great crust with same doneness at the edge as in the centre.
The sous vide method is used in many high end gourmet restaurants including Heston Blumenthal, Paul Bocuse, Michael Carlson, Thomas Keller, Gordon Ramsay and other chefs. Sous-vide cooking has become a common feature on television cooking shows such as MasterChef and Great British Menu.
There are many benefits to Sous Vide cooking. These can be summarised on two levels: nutritional and operational.
Because sous vide involves specific cooking times and precise temperatures, the risk of human error is eliminated, provided the right equipment is used. The Sirman stirred water baths offer unparalleled accuracy in temperature control.
Sous vide cooking can reduce labour & food costs, and produces a tastier, healthier product.
Blast chiller/freezers use a powered refrigeration system that fiercely drives cold air to pull down the temperature of hot food quickly to a low temperature that is relatively safe from bacterial growth, whilst maintaining food quality. Bacteria multiply fastest between +8°C and +68°C. By reducing the temperature of cooked food from +70 °C to +3 °C or below within 90 minutes, the food is rendered safe so it can be safely stored in chilled or frozen form for future reheating. Food temperature and chilling time must be able to be controlled and monitored simply in order to control these decisive factors in order to comply with the current requirements to chill food items from +70°C to +3°C in 90 minutes in a cook-chill operation.
A blast chiller is an integral part of any cook-chill operation, as the time taken to cool products is major factor in preserving the appearance and taste of the food, preserving the vitamins and nourishment value and preventing the growth of bacteria. Cooling hot foods in a fridge already containing chilled foods is very dangerous as it will raise the temperature of all of the food in the fridge and pose a major food safety risk.
With Blast Freezing current European guidelines recommend that food be reduced from a temperature of +70ºC to –18ºC in no more than 240 minutes. With blast freezing colour, texture, flavour, structure and nutritional value is locked in. Delicate food surfaces such as pasta and fruit are protected, as rapid chilling stops an “ice skin” forming which otherwise dehydrates and damages the products’ appearance. Blast freezing also helps to keep food looking good. The slower food freezes, the larger the ice crystals formed; and large ice crystals can damage food, dry it out, and break down the physical structure leaving you with an unusable product. Air chill/freeze temperatures are fully adjustable, depending on the food to be chilled, to ensure your end product is of the best quality.
Blast chilling/freezing of food also makes it possible to separate the preparation and cooking activities from the serving. This enables the kitchen to utilise preparation and cooking equipment in a more even manner throughout the day, resulting in a reduction in stress at peak periods.
Kitchens with blast chillers and freezers throw away less food. Food left over, from a hot servery for example, can quickly and safely be chilled for later use, with complete confidence in its quality and safety. Once prepared and chilled, only the correct numbers need be reheated, as legislation states that chilled food can be safely kept below +3ºC for up to 5 days after production. Blast chillers can even be used to chill wine, cans or other drinks, buffet dishes, salads and serving dishes.
Vacuum packing is a method of packaging, storing, presenting and then cooking food. Appropriate types of food are stored in an airless environment, usually in an air-tight packaging to reduce the growth of microorganisms. The vacuum environment removes atmospheric oxygen, protecting the food from spoiling by limiting the growth of aerobic bacteria or fungi, and preventing the evaporation of volatile components. Vacuum packaging food can extend its life by up to 3-5 times.
The vacuum packer has also become an essential piece of kitchen kit for many chefs and caterers who gain specific benefits in terms of advanced food preparation, portion control, spread workload, reduced food wastage, lower food costs, safer food storage, higher standards of food hygiene and sous vide or water bath cooking.
Key advantages can be gained in the kitchen from vacuum packing and storing pre-prepared foods such as fresh or sliced meats, fish, poultry, vegetables, fruits, salads and cheeses for several days without any deterioration in quality and pre-portioning soups, sauces and entire dishes to reduce food wastage. All these benefits contribute to increasing the efficiency of the kitchen and the possibility of offering a wider choice on the menu. All food – both cooked and raw – can be hygienically stored in vacuum pouches for storage in one refrigerator or effortless transported between locations thus minimising the risks of cross-contamination.
Moreover, vacuum packing has advanced over the years and progressed from purely being a shelf life extender and portion control tool into a forward thinking cooking technique in its own right. Sous vide cooking refers to a cooking technique by which ingredients are sealed in a pouch under vacuum, that are subsequently cooked at precisely defined temperature to reach a desired result. This gentle cooking method has proven to be an innovative tool for a growing number of leading chefs, and continues to grow in popularity. This method is one of the most important culinary innovations of modern times and heralds in a new era of gastronomy, including new cooking times for service that keeps meat tender, fish succulent no matter how long it’s been cooked.