Cold-pressed juice
Making cold-pressed juice is a two-step process. The first stage is to shred the fruits and vegetables into a pulp. Typically the shredding process uses a steel rotating disc. Produce is loaded into a large hopper feeding tube and typically falls into a filter bag. The second process is the hydraulic press; this exposes the shredded produce to extreme pressures between two plates. The pressure causes the juice and water content from the produce to drip into a collection tray below, leaving behind the fibre content in the filter bag. The fibre left behind is generally composted, recycled in food products or discarded.
Reverse osmosis
In addition to desalination, reverse osmosis is a more economical operation for concentrating food liquids (such as fruit juices) than conventional heat-treatment processes. Research has been done on concentration of orange juice and tomato juice. Its advantages include a lower operating cost and the ability to avoid heat-treatment processes, which makes it suitable for heat-sensitive substances such as the protein and enzymes found in most food products.