Compressed Air In The Food & Beverage Industry

Chopping, Cutting, Slicing & Dicing

Most of these operations are carried out by compressed air-driven tools, including saws, knives and mandolin blades. These can be mounted on a rotary table or travelling carriage. Chopping foodstuffs into a coarse pulp requires a rotating bowl and high-speed rotary blades, which can be programmed for the time and degree of chopping.

Bacon slicing, cheese grating and fruit fanning can be undertaken with compressed air tools, dicing vegetables for freezing, or canning and chopping meat for processing. Precision adjustments can be made for size, thickness, angle and direction of cutting. More sophisticated designs allow for variations in product uniformity to offer a more natural result.

Ingredient Dispensing

Compressed air is used to push materials through static or flexible pipework to move them from the point of supply to the point of use or to transfer materials from the delivery point to in-plant storage. A compressed air pump will create a vacuum at the receiving end of the transport, drawing liquids, grains or powders through the pipework. A series of valves open and close ports where the ingredients are to be dispensed and can be precisely programmed for the timing and amount of material to be issued. Items can be placed on a conveyor or rotary table, passing beneath a dispenser.

Mixing

Pneumatic mixers use compressed air or air bubbles to mix materials and consist of a mixing silo and usually a conveying tube, which dispenses and spreads the materials. They have nozzles at the side or bottom of the mixing silo, which intermittently pump in high-velocity compressed air or gas. Increasing the air velocity agitates the powder bed, causing bubbles to form and initiate blending. Powders at the bottom expand when they're aerated and cause other particles to reorient themselves and rise.

Moulding

Other food and beverage industry uses for compressed air include blow-moulding hollow objects. This is similar to glass blowing, where compressed air is forced into a hollow tube, and a molten material is extruded from it to form a particular shape dictated by a mould. Most hollow polyethene (PET) products are produced this way, including milk, water, soft drink bottles, and bottles for cooking oil, salad dressings, and honey.

Shaping

Pneumatic presses can be used for mincing and pulping operations, where the press contains a central pneumatic inflatable membrane or is pushed down by a pneumatic actuator. They also form and shape many items, such as bread and pastries, confectionery and cheese. Many of these processes are now governed by automated controls and sensory equipment. This can assess the condition of the food to be processed and adjust the degree of processing accordingly.

Packaging

Vacuum pressure is very well adapted for the efficient lifting, placement and manipulation of food products, especially if they're delicate or asymmetric. Items can be placed on conveyors or rotary tables and picked up by vacuum cups or pneumatic grippers to be put into cartons or packs. Compressed air systems are also used in food packaging for tasks like forming bubble packs and cleaning, filling and sealing all package types.

What To Consider When Using Compressed Air?

Various matters must always be considered when using compressed air to ensure absolute hygiene, compliance with standards, and the smooth running of the application.

Contaminants

Solid particulates, including spores, dirt and rust from metal components, can adhere to parts and clog up nozzles. Downstream pneumatic tools and equipment will be damaged if subjected to contaminated compressed air, causing potential downtime, expensive repairs and loss of productivity.

Eliminating moisture for compressed air applications in the food and beverage industry is imperative, as it provides an ideal breeding ground for fungi and microorganisms. Water may collect in areas of the piping system where the compressed air comes into direct contact with foodstuffs. Microorganisms or fungi could then be transferred into food containers or products.

It's also crucial to consider the ingredients to which the application's parts may be exposed. Ingredients like sugar crystals, ice or dough mixtures can interfere with the proper operation of the cylinder by forming deposits on the piston rods. These residues can be removed by installing metal (rather than plastic or rubber) scraper rings with the piston rod seal, preventing any deposits from building up.

Air Preparation

To eliminate contamination, the compressed air must be adequately prepared before it reaches any active part of the system. This entails installing an FRL unit and ensuring it's regularly maintained. Lubrication-free or pre-lubricated assemblies that use food-grade grease and don't demand any additional lubrication should be installed whenever possible.

Automatic stainless steel or tapped manual drains are often used as filter options. These remove any excess liquid that might otherwise collect and drain straight onto the floor. Non-relieving regulators are also advisable for the food and beverage industry, as they don't allow any liquid or gases to escape into the atmosphere.

Energy Consumption

Reductions in the type of materials used in, for example, PET bottles, mean that the energy required to produce them can also be reduced. The amount of PET previously needed for a 450g bottle was over 14g. Reducing PET's amount per bottle demand to under 10g has decreased the demand for compressed air pressure, leading to significant energy savings.

Over the last 20 years, advances have been made in developing compressed air recovery systems. In this way, energy savings can be increased by recovering and reusing high-pressure compressed air from the exhaust for other processes. This compressed air can be recirculated as pre-blow air in a moulding application, for example, or as service air for the blowing apparatus. In some traditional types of machinery, this process can recover up to 60% of the exhausted compressed air for reuse in lower-pressure circuits.

Food-Safe Pneumatic Components

Clean design is essential when manufacturing food-grade pneumatics, as strict hygienic standards cannot be compromised. Pneumatic products in the food and beverage industry are commonly made of high-performance stainless steel, which can withstand the corrosive materials often used in wash-downs. Some components, including valves, may be designed for mounting within a protective enclosure. Still, cavities or crevices may exist in the enclosure where bacteria can linger and must be cleaned even more carefully.

Stainless steel is expensive, so cheaper alternatives are being developed for food and beverage applications that combine it with anodised aluminium parts. Moving parts such as pistons and bearings can now be constructed from low-friction thermoplastics with high rigidity and excellent dimensional stability.

Critical Issues And Compressed Air

Cleanliness, hygiene and sanitation are critical in the food and beverage industry. Failure to comply with the requisite standards can lead not only to prosecution and fines but to illness, a consequent loss of customer confidence, and even the potential of bankruptcy. The food and beverage industry uses many compressed ingredients, but the principle behind all applications is that they must be scrupulously clean and sterile.