A juice extractor is a machine that mechanically separates juice from the solid part (pulp) of most fruits, vegetables, leafy greens, and herbs. The pulp is usually discarded, but can also be used in muffins and breads or composting.
Most juice extractors are electric, which requires less effort than their manual counterparts. A juicer differs from a blender: a juicer separates the juice from the pulp, a blender mixes everything together by liquefying the pulp.
There are three main types of juicer: centrifugal juicers use blades and a sieve to separate juice from pulp; masticating juicers that 'chew' fruit to a pulp before squeezing out the juice; and, triturating juicers that have twin gears to first crush fruit and then press it.
Masticating and triturating juicers can also juice wheatgrass unlike centrifugal juicers that cannot break the fibres of the grass.
The single auger masticating juicer uses a profiled screw style moulding to compact and crush fruit and vegetable matter against a static screen allowing juice to flow through the screen while pulp is expelled through a separate outlet.
Twin gear triturating machines are usually the most expensive juicers offering the best juice yield. Twin gear juicers employ two metal counter rotating gears to crush the juicing fodder. The precise tolerance of the gears allows the juice to flow through the gap between the gears while the large pulpy matter passes along the top of the gears and is discharged.
Several kitchen tools are made for extracting juice from various foods. There are several varieties of hand-held lemon and lime presses. There are also small devices that do not use electrical power and can be used for extracting juice when a large amount is not needed.