In a commercial kitchen, organisation is crucial. And it is even more so in a large scale kitchen. When supplies come in, where it is stored and how it is stored has to be properly organised. A proper Standard Operating Procedure (SOP) right from the star t will help a kitchen work smoothly. In terms of storage, food items need to be packed properly to avoid cross-contamination and rotting that eventually leads to wastage. Many kitchens use cling wrap for meats, fruits and vegetables. However, it is possible for meats to start having freezer burns and even turn colour and / or texture due to atmospheric impact. Although they aren’t technically spoilt, it may still affect a dish.
To minimise atmospheric impact, air has to be removed. One of the earliest accounts actually dates back to a time before the World War II. Air was removed from rubber latex bags and then sealed which helped increase shelf life of frozen products. It did not take off until the 50s when vacuum packaging machines became available. The efficacy of this technique soon caught on and Chefs begun employing vacuum packing to fresh food. Simply by removing atmospheric air from its surrounding environment, fresh and dry items keep longer and better. It has advanced to the point that we can even cook food directly with the bag using the sous-vide method. However, the idea of food in plastic could still be a concern for many and to help us better understand the benefits and the way to do it, we have ORVED’s Marzia Burighel to share some insights.
WHY VACUUM FOOD?
Kitchens cooking a lot of food likely also order supplies in large volumes as well and many times produce are not used upon delivery. Therefore, vacuum packing plays the role of preserving quality of products’ structure, to improve their shelf-life and to reduce the weight loss.
SEALING & STORING
Theoretically, it is possible to vacuum any type of food product but one has to understand the composition of each item as some items might not respond well to vacuum. In relation to this, Marzia points out 3 important factors to consider when using vacuum.
(A) Solid Products
• The vacuum pressure vary between textures of products and typically can handle most produce such as meat, fish, poultry and hardy vegetables such as carrots, zucchinis or potatoes.
• Some chefs prefer not to vacuum mushrooms and garlic as these have natural internal gas production which causes the bag to inflate. It is possible to pack them after cooking or packed for sous-vide cooking.
• Tomatoes are considered fragile and unsuitable to withstand vacuum pressure although whole cherry tomatoes are strong enough.
• However, if you pack delicate items like peas, tomatoes and asparagus, the company recommends using a preservation liquid (ex: saline base water or oil) to reduce product compression.
This liquid could be used to cook the product, too. It is also possible pack very frail items like lettuce and cakes with ORVED’s Modified Atmosphere Packaging (MAP) vacuum process.
(B) Product Temperature
The most ideal temperature would be +3°C and a maximum of +6°C. This prevents liquid from steaming which results in weight loss, erroneous reading level, pump damages from oxidation and oil watering. Food, whether raw or cooked – needs to be packed cold. Blast chill cooked foods before vacuum packing and it can be kept in the refrigerator till service time.
(C) Product Volume
Know how much you will be packing because volume that can be packed is limited by the machines. Most manufacturers would have bags in different sizes.
PACKING FOR STORAGE VS PACKING FOR COOKING (SOUS VIDE)
Technically the process is similar but note that you need a deeper vacuum level for sous-vide cooking. You will need to remove as much air as possible to avoid the risk of bags inflating due to the gases present in the product. As for sealing for storage, different pressures would be required to ensure better “breathing” of the raw product.
A popular perception of bags is that they are unhealthy because you are cooking food in plastic. This is not exactly true because food safety regulations have approved certain materials as food grade quality and in Or ved’s case it uses PA/PE material for its storage bags. They are designed with a special multilayer structure to allow storing of both raw and cooked products. If you want to cook food ala sous-vide (immersion of bag into water bath); Marzia recommends its OPA/PP material bags as it is able to withstand up to 121°C being in water or steamed for up to 30 minutes. For cooked food sealed for rethermalisation, the regular PA/PE can stay in hot water or a steam oven at 65°C/to 85°C for a maximum of 30 minutes without any plastic being released into the food.
COST DIFFERENTIALS – PANS VS SEALED BAGS
Typically, kitchens use Gn pans or storage bins and they are undeniably cheaper. At what point would vacuum packing be actually a cost efficient approach? According to Marzia, thestorage bags, cooking bags and machine are definite initial investments. However, if you consider waste reduction from longer shelf-life of food and / or reduction of washing cost by cooking in a steam oven and not dirtying it; vacuum packing could be considered as par t of your large scale cooking operations.
A counter top unit, the open end of the vacuum sealing bag is placed inside the machine and is sealed by clamping the lid down. Air removal and sealing are done outside the machine that operates with heat. To effectively seal a bag with an external sealer, materials should have uniform thermoplastic monolayers or with materials with several layers; at least one being thermoplastic (pliable above certain temperatures and solidifies when cool). An external sealer would suit smaller operations with limited items to seal.
Single Vacuum Chamber Machines
The entire product is placed into the machine where the lid is closed and the chamber sealing machine removes all air from inside the chamber. Upon completion of the vacuum cycle, the heat bar rises and applies a seal to the bag. With a chamber machine, you can seal soups, sauces and other liquids because the bag is contained within the chamber and will not collapse around the liquid until sealed. Compared to a limited type of bag accepted by the external sealer, the chamber is able to seal a wide variety of flat bags which cost less; particularly if you seal a lot of items.
Double Chamber Vacuum Packaging Machine
Basically works with the same principle as a single chamber but with a lid that generally swings from one side to another. Production speed can be increased and is typically used in medium volume facilities.
This can be an option for cost conscious kitchens where vacuum packing is done on a nominal basis. The pistol style makes it easy to hold and runs on rechargeable batteries able to seal up to 50 bags with one full charge. However, range of sealable items are limited to dry goods and not liquids.
As we scratched the surface on the theory of vacuum packing, we hope that it has sparked questions which your selected Manufacturer would be able to tell you more about. In the meantime, you can explore possible ideas on managing large volume cooking alongside a more efficient packing method.