Slow speed cold press juice extractors usually operate between the 40 to 200 rpm range. They are generally viewed as purpose built, speciality items, which appeal to a rather niche market; as opposed to high speed juicers, that boast a very high sales volume in comparison.
We chew our food at about 30 to 60 chews per minute via a cold press masticating process, thus insuring maximum nutrient availability. If our mouths were to imitate high speed centrifugal juicers, we would be chewing at an incredible 1,000 to 30,000 bites per minute ... That is rather unnatural!
Some discerning customers insist on using only 'Cold Press Juicers' with speeds ranging from 200 rpm and less, to preserve as many nutrients as possible. Cold press juicers separate / extract the juice from the produce via a slow speed 'cold press' masticating process. Because the nutrients are preserved, the juice tastes stronger (much better) and has a much longer shelf-life (can be refrigerated longer.)
Cold press juicers are especially appealing to health enthusiasts, sports people, convalescing people and the elderly, and are thoroughly recommended by Dr. Sandra Cabot.
Cold press juicers can be either: 1) horizontal single auger (masticating), 2) horizontal twin-gear (triturating) or 3) vertical (masticating) styles:
1) HORIZONTAL SINGLE AUGER JUICERS - masticating type
Singer auger / gear cold press juicers are usually more affordable due to their simple design.
They incorporate a slow turning auger to crush and squeeze (masticate) the fruit and vegetables. They usually expel
the pulp through a pressure adjustable end cap into a pulp bowl, while the juice filters through a sieve into the juice bowl.
Single gear / auger horizontal cold press juicers usually take up to 8 minutes to extract 1 litre of carrot juice; however, the resultant juice is an extremely high quality, has more nutrients than high speed juicers, is very rich in texture and has a very strong, natural taste.
They are usually very tough, muti-functional and come with everything you need to make: sorbet, ice-cream, noodles, pasta, sausages, vegetarian or meat patties, pasta, noodles etc.
They are also very easy to use and clean and are very popular for home use and especially juice bars.
2) HORIZONTAL TWIN GEAR JUICERS - triturating type
Twin-gear juicers are generally more expensive due to being higher precision juicers.
They incorporate two slow turning gears that rotate inwards, leaving a very small gap between them. They cut, crush and squeeze (triturating) the fruit and vegetables to extract the juice. They usually expel
the pulp through the end into a pulp bowl (some twin gear juicers have a pressure adjustable end cap) while the juice filters through a sieve into the juice bowl.
Twin gear horizontal cold press juicers usually take up to 6 minutes to extract 1 litre of carrot juice; however, the resultant juice is an extremely high quality, has more nutrients than high speed juicers, is very rich in texture and has a very strong, natural taste.
They are usually very strongly made, muti-functional and come with everything you need to make: sorbet, ice-cream, noodles, pasta, sausages, vegetarian or meat patties, pasta, noodles etc.
They are also very easy to use and clean and are very popular for home use and even juice bars.
The twin gears of the Greenpower Kempo cold press juicer at right turn at just 160 rpm, is very easy to operate and was endorsed by choice tv independent juicer comparison / juicer review in 2010 for producing a very high quality 'living' juice.
3) VERTICAL SINGLE GEAR JUICERS - masticating type
Singer auger / gear cold press juicers are usually more affordable due to their simple design.
These are a relatively recent addition to the market (2010 onwards.) They still use a gear to slowly crush the fruit, but the vertical format means that they have a smaller footprint than other cold press styles.
Single gear / auger vertical cold press juicers incorporate a slow turning auger that incorporates gravity, to crush and squeeze (masticate) the fruit and vegetables. They usually expel
the pulp through into a pulp bowl, while the juice pours into the juice bowl.
Single gear vertical auger juicers are usually much faster at juicing, and in the case of the LifeSpring Slow Juicer takes only about 2.5 minutes to extract 1 litre of carrot juice, which is very impressive! The resultant juice is extremely high quality, has more nutrients than high speed juicers, is very rich in texture and has a very strong, natural taste.
They are usually muti-functional in nature and can often also be used to make sorbet, ice-cream, noodles, pasta, sausages, vegetarian or meat patties, pasta, noodles etc.
They are also very easy to use and easy to clean, and are very popular for home use and especially juice bars.
The auger of the LifeSpring Slow Juicer at right, turns at just 50 rpm clockwise, and the juicing screen turns at just 25 rpm anti-clockwise, producing a high quality 'living' juice.
BENEFITS OF COLD PRESS JUICERS
Cold press juicers are mostly more expensive than centrifugal models. Despite this, they usually have a smaller chute
size and no dishwasher-safe parts or cord storage. They're also slower at processing and you sometimes need to cut the fruit
and vegetables more finely to get them down the chute.
However, there are several advantages to non-centrifugal type (cold press):
If you prefer to store your juice rather than drinking it soon after making it, one of these machines may suit you.
You can also use some of them for food processing, mincing, grinding coffee beans and for making sausages, pasta / noodles, seasonings, nut butter, soy milk, baby food and ice cream.
They have fewer parts and are easier to clean.
Cold press juicers can juice wheat grass and herbs.
Their warranties are generally longer than those for centrifugal juicers.
They're much quieter than centrifugal models.
Generally the juice remains fresh for much longer.
Cut produce into smaller pieces so that they can be fed through the juicer more easily.
Juice soft fruit first before juicing hard fruit - this will help to maximise extraction.
If you're using herbs like mint, add the leaves in between the fruit / vegetables to get the most out of them.
Add small fruits like grapes or strawberries in small handfuls.
Really soft fruit like bananas in particular can be more difficult to juice. Add them at the start and as the next piece of fruit is added it will help the banana nectar to move through the juicing screen.
Manufacturers claim that the juice from cold press machines is more nutritious and that it'll stay fresh and tasty for up to 48 /72 hours. According to the makers, the gentle, slow-turning action of a cold press machine produces a greater quantity of actual juice, which
retains more vitamins, minerals, enzymes, phytochemicals and fibre than that produced by other methods. Their argument is
that high-speed centrifugal juicers heat up the juice, which allows air to enter and therefore causes damage to some of the perishable
This is very similar to submarine propellers of old having just 2 blades turning quickly to travel at say 20 knots, creates a lot of turbulence and heat in the water, which creates lots of bubbles which explode and is easily heard by sonar. Great advances were made by having 4 blades instead of 2, which meant they submarine could travel at 20 knots, but with less revolutions of the propellers, which meant less heat / friction, which meant less bubbles, which meant less noise - hence stealth technology. In time many submarine propellers had 6, 8 or even 10 blades, which resulted in even less heat / noise.
As cold press juicers 'press' the juice out slowly, it minimises the heat problem that high speed centrifugal juicers have, which heat / oxygenate the juice to varying levels.
choice tv has reviewed / tested (2009) samples from carrot juice from high speed and cold press juicers in a laboratory,
analysing and comparing the various minerals (potassium and calcium), Vitamin C and the phytochemicals alpha and beta-carotene, to see if the non centrifugal
juicers did extract or retain more nutrients.
The juice from all the cold press juicers(non centrifugal juicers) contained about double - in some cases triple - the calcium of the juices
produced some of the centrifugal juicers except for two models (however, the
levels were small compared to the RDI.)
The juice from the Greenpower Juicer has more beta-carotene compared with juice from every other juicer in the test.
Potassium was much the same for all juices tested.
Vitamin C quantities were too low to measure accurately.
HOW LONG DID THE JUICE STAY FRESH?
The 2009 test was also to see how long the juice would stay fresh for. A sample of apple juice was used from each juicer,
refrigerated it for 48 hours, then evaluated for colour, overall appearance, smell and texture, to test the claim that juice from
non-centrifugal juicers holds up longer.
High speed centrifugal: The apple juice from the centrifugal juicers separated and went brown a few minutes after juicing. After two days it was noticeably deteriorating, didn't smell fresh, had a hard froth on top and a layer of sediment at the bottom - indicating a higher
level of oxidation.
Cold press juicers: By contrast, the juice from the non-centrifugal juicers didn't separate, smelt fresh and looked palatable and green after 48
hours in the fridge, indicating less oxidation.
choice tv concluded that it's possible that the oxidation or friction from higher speed centrifugal juicers turns the juice bad faster than the slow turning
High Speed Masticating Juicers
High Speed Centrifugal Juicers
Usually operating between the 1,000 to 30,000 rpm range.
High speed centrifugal juicers are very common, popular and usually inexpensive. They use a rotating blade to cut fruit and
vegetables into a liquid state at really high speeds, which is then forced through a strainer.
They have parts that spin at particularly high speeds, which can result in a lot of vibration, especially if the produce is not
evenly distributed. Some high speed centrifugal juicers vibrate so much, they even can 'walk' across the bench during use!
High speed centrifugal juicers usually have many good points such as:
really fast to make a juice drink!
relatively inexpensive to purchase
large chute for juicing whole apples etc
few parts and are easy to assemble
easy to operate
reasonably easy to clean
High speed centrifugal juicers may have a few bad points such as:
cannot juice wheat grass and leafy greens very well, or at all
resultant juice can be a combination of juice plus finely cut produce blended into the juice
can be noisy
may require regular pulp removal and cleaning
some have serious vibrational issues
generally extract less juice than slow speed cold press juicers
vibration woes - centrifugal juicers have parts that spin at very high speeds and this results in significant vibration with some juicers, especially if the fruit is not evenly distributed. Some high speed juicers tested professionally in an unbiased laboratory vibrated so much that they were literally
'walking' on the bench during use!
many people and some unbiased testing laboratories claim that the the juice (colour, appearance, taste, quality) does not keep as long due to it being oxygenated at extremely high speeds, and therefore needs to be consumed rather quickly
High speed centrifugal juicers are excellent for busy people who want a quick 'juice boost' on the run; supplying instant energy and nutrients as and when needed.