Compressed air can be used to generate vacuum used in the packaging process, air is also used in conveying systems to move food and ingredients.
When beer is bottled, its residual oxygen content must be kept as low as possible. To this end, breweries employ two different methods, either alone or in combination. Bottles are flushed with CO2 and filled with beer via a long-tube filler. In this case, the filler tube is inserted into the bottle and the bottle is flushed with carbon dioxide before actually being filled with beer. This method consumes a relatively large amount of CO2. Bottles are evacuated and then flushed with CO2. This method greatly reduces carbon dioxide consumption because most of the oxygen is already extracted.
PET bottle blowing
High pressure oil free compressed air is fed into the bottle blower machine moulds where preforms are heated and the plastic is streched to form the bottle.
Air hoists and cylinders are used to move products, at very high speeds able to keep up with modern production practices.
Food filling machines
Food filling machines use compressed air to fill products such as cakes, pies, and liquid products.
Compressed air is generated to operate pumps such as diaphragm pumps to move liquid products in the production and filling process.
Nitrogen generators produce nitrogen from compressed air supplied by a dedicated air compressor. The compressor is mounted at the beginning of the system and passes compressed air through sets of filters to remove the impurities before entering into the generator. The filtrated air then passes through another filter that eliminates oxygen and carbon dioxide molecules resulting in a high purity of hydrogen gas.
Compressed air is used as a clean medium for cutting products. It is also used for peeling products such as fruit and onions.
Filtration units are used for filtering and cleaning liquids. The choice of the filtration membrane (nano-, ultra- or microfiltration) depends on the product requirements. Crossflow filtration, for example, involves re-circulation of the feed stream across the membrane surface caused by the pressure difference between retentate and permeate. During the filtration process, particles deposit on the membrane surface which are gradually removed by the cross flow velocity generated by the pump to minimise polarisation.
MAP storage and packaging
To prevent fruits or meat from maturing, they are stored in cooling chambers under so-called controlled atmosphere conditions: after having been exhausted, the cooling chamber is filled with inert gas. Alternatively, the inert gas is carefully compressed into the packaging.
Filing and closing machines
When bottling beverages, cosmetic or pharmaceutical products, the bottle is at first evacuated before being filled to make sure the product reaches the customer in good quality.
When beer is bottled, its residual oxygen content must be kept as low as possible. To this end, breweries employ two different methods, either singly or in combination:
Bottles are flushed with CO2 and filled with beer via a long-tube filler. In this case, the filler tube is inserted into the bottle and the bottle is flushed with carbon dioxide before actually being filled with beer. This method consumes a relatively large amount of CO2.
Bottles are evacuated and then flushed with CO2. This method greatly reduces carbon dioxide consumption because most of the oxygen is already extracted.
The surrounding pressure exerts a mechanical influence on the product that can greatly alter the external shape. For this reason, the MAP process has been the method of choice in many application areas. In this process, products are packaged in modified atmosphere and the oxygen removed. The product is enclosed in a blister package, placed in the vacuum chamber and evacuated. The modified atmosphere is then injected and the blister package and food are sealed with a protective film.
Using this method the food retains its original shape and meats present a suitably red appearance to customers, even after extended storage.
The packaging process has numerous requirements for vacuum pumps, as during evacuation of only air, but also water vapour, fat and spice mixtures are evacuated. Because of higher requirements for quality of food with regard to flavour, colour, homogeneity and durability, meat processing uses more and more vacuum, too, e.g. in filling machines, tumblers and cutters.
Dairy processing and milking
On yogurt filling machines the vacuum pump serves to position the lids on five pre-filled yogurt containers simultaneously. Suction cups on the machine grip the lids, separate them and move them into the correct positions. n addition to transporting the milk, the vacuum used in milking systems performs other tasks as well, such as attaching onto the udder and holding the weight of the milking claw assembly to the teat.
Liquid ring pumps and side channel blowers offer significant advantages over traditional oil-lubricated pumps because they use no oil. The side channel technology has the additional advantage of requiring no water connection - and it is optionally available with frequency converters.
Preservation of cooked food
Fruits, vegetables and their subsequent products, such as mash and purée, are preserved through cooking. This involves heating a small amount of water to generate steam which removes the air. To obtain a high product quality and energy efficiency, the preservation process is carried out under vacuum.
Tobacco packed in bales is so brittle that without proper humidification it would crumble into dust when processed further. A vacuum pump extracts the air from the bales and replaces it with steam, sometimes supplemented with aromatic substances. This approach is also used for other types of food in need of humidifiation.
Before any further processing can take place, fish and molluscs must be gutted and cleaned. Worktables are outfitted with suitable vacuum nozzles that extract the entrails from the fish. A central vacuum system then pipes the combination of liquid and coarse particles through a filter where they are separated for proper disposal. The same is possible in the poultry sector.
Sterilizing of tea and spices
Tea and spices imported from tropical regions are shipped in bales, which very often contain pests, insects, fungi and bacteria that must be destroyed before further processing can occur. This is done by placing the bales in vacuum containers and extracting the air. The bales are then injected with steam or a sterilized gas.
To produce sausages a meat mixture is chopped into small pieces and mixed with spices and other additives. Extracting air during the chopping and mixing processes can help prevent the mixture from oxidizing, which would have a negative effect on the sausage's flavour and appearance. The air is evacuated by means of a vacuum of about 100 mbar. The pump used must be insensitive to the meat particles and liquids that are also extracted.
Many food stuffs need to be dried during the production process and vacuum is used for that purpose.