Frequently Asked Questions about Vacuum Packers
What kinds of food can I vacuum pack?
In theory all foods can be vacuum packed but in reality the most likely types of food that are routinely vacuum packed are fresh foods such as meat, fish, poultry, vegetables, fruits and stocks and sauces to extend shelf life and sous vide cook as well as dry foods such as cereals, nuts, cured meats, cheeses, smoked fish and coffee to solely extend shelf life.
There are some foods which for their own unique reasons you might not wish to vacuum pack or need special attention e.g. tomatoes, garlic and cruciferous vegetables such as broccoli, cauliflower, cabbage and brussel sprouts. It is best to part-freeze tomatoes before vacuum sealing and pre-chill garlic, simply because the gases will not expand when frozen or chilled. Cruciferous vegetables should only be vacuum sealed after blanching, cooling and drying.
Mushrooms also need special attention to their preservation. Before attempting to vacuum seal mushrooms they should either be marinated in a sauce or fully frozen.
You may also find that burgers and sausages release air from within their mince meat after vacuum packing. The bag will look ballooned shape. It is not that air has entered the bag, it is trapped air already contained within the produce that cannot be extracted by a vacuum pump in the first place.
How long will vacuum packing keep my food fresh?
How long food will remain durable after vacuum packing depends on more than just the degree of reduced oxygen. Factors such as temperature, pH, nutritive content, degree of oxygen reduction, time (age and condition) and moisture content also control the speed and level of food deterioration. However, it is a well established fact that vacuum packed food kept in the fridge at 3° C can keep food fresh for up three to five times longer than afforded by refrigeration alone. In addition, cold frozen vacuum packed food does not suffer the affects of freezer burn.
It is worth noting that there is no legal definition of how long food will last in a vacuum packed environment and therefore if you are vacuum packing for any commercial venture it is worth investigating your own shelf life guidelines by undertaking a thorough research and development process in consultation with a micro-biologist. If you using a vacuum packer in the kitchen of a restaurant or other hospitality venue you should have in place critical control points in your HACCP plan dedicated to the vacuum packing machine, the vacuum packing process and other processes such as chilling, storage and sous vide cooking.
How long does it take to vacuum pack a piece of food?
In essence the workings of a vacuum packer are very simple. The vacuum packing machine consists of a hermetically sealed chamber from which all or part of the air inside the chamber is extracted by a pump consisting of rotating blades that absorb and expel air. A vacuum pouch is then sealed with a heat produced by thermal strips. In some models it is also possible to create a vacuum and seal the bag inside a box chamber (called a chamber machine) and in others it is possible to drawer a vacuum from a pouch whose open pocket is placed under a lid of a machine and heat sealed whilst under vacuum pressure (called an external suction vacuum sealer).
Most vacuum packing machines operate on a cycle time of between 20 to 45 seconds. Some more powerful machines with larger pumps can be quicker to operate, e.g. the cycle time can be lowered to 15 – 20 seconds. Some machines that have less powerful pumps will take longer. Basically, the more air that needs removing the longer the process will take to reach a maximum vacuum. High density blocks supplied with a chamber type vacuum packer will speed up the vacuum process by reducing the amount of air that there is to be removed.
Another measure that you can take to increase productivity is increase the number of pouches to be vacuum packed by placing vacuum pouches efficiently along the thermal heat strip. This can be done by placing pouches side by side and on top of each other. For example, most vacuum pouches are made from co-polymers and can burn the inside of the pouch at a lower heat than the outside. This means that they will seal the pouch without burning the pouches together.
What about vacuum packing liquids?
The vacuum packing of liquid products such as marinades, sauces, stock, soup, oils etc. is more complex than solid foods. This is because water molecules start boiling under extreme pressure at room temperatures. What happens is that the liquid will start to fizz or boil even though no heat is being applied and can start pouring out of the vacuum pouch and invisible water vapour can be aspired into the vacuum pump.
It is therefore recommended to always vacuum pack liquids in a pre-chilled state and use a vacuum chamber machine with an inclined shelf or a vertical drop down zone such as featured in the Cuisson SV31 & SV41 models. The force of gravity will hold the liquids in the pouch.
Additionally we highly recommend running a dehumidification programme on a weekly basis to burn out any vapour that may have reached the inside of a vacuum pump. A dehumidification programme effectively runs the vacuum pump between an 80% and 100% vacuum for about 20 minutes to heat the vacuum pump oil so hot that any water vapour that may have reached the pump is eliminated.
Whilst vacuum packing liquid in an external suction machine can be done with extreme care, we don’t really recommend it in anything other than a vacuum container. This is because the suction process can lead to the liquid being drawn into the vacuum pump and damaging the internal mechanisms of the machine.
What do I need to look out for when purchasing a vacuum packing machine?
Culinary Innovations recommends talking through the issues you face when choosing a vacuum packing machine. There are all sorts of machine types which reflect on your budget, as well as issues with regards to degree of vacuum pressure, pouch types, dimensions and speed.
Essentially we offer two distinct types of vacuum packing methods:
- Traditional chamber types that create a vacuum in a pouch by placing the entire contents of a pouch within a chamber and extracting the air from the chamber before heat sealing the pouch.
- External suction machines which use a vacuum pump to suck air out of a pouch from the exterior of the appliance, i.e. by placing the open end of the pouch underneath a lid, withdrawing the air and then heat sealing the pouch.
Both methods require high power vacuum pumps and heat sealing capabilities. Generally the chamber vacuum machine is consider to be the superior allowing you to vacuum pack with greater air pressure (0.5 mbar instead of 150 mbar) and can give you greater options in terms of preciseness of vacuum, double sealing and/or cut of seal, additional thermal sealing strips, inert gas and “softair”. Please contact us for more details on these options.
In some circumstances it is better to use an external suction machine, e.g. in some forms of dry packaging, medical applications and in the home or small commercial application where space is at a premium and budgets are more restrictive.
What kind of vacuum pouches do I need to use?
In order to vacuum pack you will need a special pouch called a vacuum pouch. These pouches are food safe on the inside and air impenetrable on the outside. There are many different types of vacuum pouches for different applications and for vacuum packer machine types. More information on vacuum pouches can be found on our vacuum pouch page.
Are there any dangers using a vacuum packing machine?
Yes there are dangers you need to be aware of when vacuum packing.
Firstly, your vacuum packer should be clean and safe to use. Your Environmental Health Officer will want to see a hygiene regime in place that ensures that your vacuum packer is cleaned on a regular basis and that there is no cause for concern of cross contamination of bacteria from cooked to raw foods. In fact they will insist that your have two separate vacuum packing machines to prevent cross contamination, especially of e.coli.
Secondly, and more importantly, vacuum packing is not a flawless system for prolonging the shelf life of foods. This is because certain micro-organisms classified as “anaerobic” prefer to grow in the absence of oxygen. One of these micro-organisms is one of the most deadly food-borne pathogens, Clostridium botulinum. It is therefore imperative to carefully monitor, document and control the preparation and packing conditions when vacuum packing all foods and prepare a sound HACCP food safety system and follow it diligently. This HACCP plan will include but not be limited to correct storage of food below 3° C and extended shelf life of cook/chilled products of no greater than the maximum legal limit of 10 days (preferably a lot less).
If in doubt, our best advice is to speak to a qualified micro-biologist.
What happens if my machine breaks down?
Vacuum packing machines do break down from time to time. A regular maintenance schedule will help reduce the risks of break down. This schedule will include regular use of the dehumidification programme as well as oil changes that protect the most important part of the machine, the vacuum pump. Other day to day care of the Teflon thermal sealing strips and any neoprene seals will help the longevity and quality of your vacuum packing process.
If for any reason your machine breaks down then we recommend either returning the machine to us for inspection or repair or consult a local catering equipment engineer. Either way we hold a stock of the most important parts and can obtain other parts where and when necessary.