文档介绍：外文原文:
The Honest Guide to Choosing a Juicer
In the 1930's a chap called Dr Norman Walker invented a juicer which firstly grated and then cut produce. The resulting mass was then to be put into a linen bag and placed under a hydraulic press, directing juice down a spout. (Dr Walker lived to 108 years of age - he died in a surfing accident). You can still purchase this 2-stage "Norwalk" machine for around $2000, which is a very prohibitive price indeed. And most of the juicers you will find on sale haven't evolved much since then, which brings us to...Centrifugal juicers. Centrifugal juicers work by using a flat cutting blade on the bottom of a rapidly spinning strainer. Cut produce is flung out over the sides of the strainer. Due to the centrifugal force, juice then passes through tiny holes in the strainer. Features intrinsic to this design include:
􀁺 The strainers are HUGE and a pain to clean
􀁺 The cutting blades are tricky to clean and some are particularly dangerous to handle
􀁺 The process incorporates mass oxidization and therefore a 'dying' and brown juice
􀁺 There is a lot of unpleasant froth
􀁺 Leafy green vegetables are impossible, so no herbs and no wheatgrass
􀁺 Pulp builds up in the strainer and efficiency falls rapidly
􀁺 The centrifugal force pushes a lot of pulp through the strainer, resulting in a lot of pulp in the juice
􀁺 These juicers can seriously damage your hearing, and won't be popular in a terraced house or flat, or if anyone is still in bed
Ultimately, the technology inside a centrifugal juicer is not unlike that of a tree cutter. They're spinning at up to10000rpm. The resulting frictional heat is not good for your juice.
Neither is 10000rpm an easy task for a motor when under constant resistance. The amount you can spend on a centrifugal juicer varies from £30 to over £100 - so what are you paying for? Well, in truth, mostly brand name and aesthetic design. While the cheapest of machines are certainly week hearted and not go