What You Cannot Put in a Juicer

Never put stones, pits, large hard seeds, ice, nuts or anything frozen solid into a juicer -- those break machines. Beyond that, the do-not list is really a will-disappoint list, and it has four causes: no free liquid to extract, too much starch, skins and seeds that pack a screen, and fiber that wraps an auger. Learn the four and you will never need to look a specific fruit up again.

The things that will actually damage the machine

This is the short, serious list. Everything here risks a cracked screen, a bent auger, a snapped blade or a burnt-out motor, and none of it is covered by a warranty.

• Stones and pits. Peach, plum, nectarine, apricot, cherry, mango, avocado, olive. Remove them first; the flesh is fine to attempt even where the yield is poor.
• Large hard seeds. Avocado stone obviously, but also whole dates with the pit in. Apple and pear seeds are small and soft enough to pass in the quantities a few fruit contain.
• Ice and anything frozen solid. A juicer is not an ice crusher. Partly thawed fruit is a different question -- see can you juice frozen fruit.
• Nuts, whole grains and dried beans. Hard, dry and with no liquid to extract. Some augers have a mincing attachment for this, which is a separate accessory with its own screen -- Tribest ships one with the Slowstar. Never through a juicing screen.
• Sugar cane, unless the machine is built for it. Dense woody fiber that will stall a domestic auger.
• Rhubarb leaves and other inedible parts. Nothing to do with the machine -- rhubarb leaves are toxic. Stalks are fine.

The four reasons everything else fails

None of those four will break a machine. They waste produce, block a screen and create a cleaning job -- which is a different and much smaller problem than a cracked auger. The practical rule: if you squeeze a piece in your hand and nothing wet appears, a juicer will not find any either.

What people wrongly avoid

The do-not lists circulating online are longer than they need to be. These all go through an auger machine perfectly well:

• Apple and pear seeds. Small and soft; fine in the quantities a few fruit contain. The stalk is worth removing.
• Ginger and turmeric skin. No need to peel, just scrub. Do you peel ginger before juicing covers the exceptions.
• Carrot and beet skin. Scrub, do not peel. Beet greens juice too.
• Cucumber skin. Fine unless it is waxed, in which case peel it. Best juicers for cucumbers.
• Citrus flesh. Perfectly fine through an auger -- it is the rind and pith that are bitter, which is why a citrus press exists. Can you use a citrus juicer for vegetables covers the reverse question.
• Watermelon rind, in moderation. The white part juices; the green skin is best removed. Best juicers for watermelon.
• Whole celery including leaves. In moderation. Leaves in bulk are the problem, not leaves at all.
• Kale stems. They juice; they are just tougher than the leaf. How to juice kale.

What to look for in a machine, if your list is awkward

Two published features change how forgiving a juicer is about marginal produce, and both are worth checking before you buy:

1. 1.A reverse function, which is how you back a wrapped wad of fiber out of the auger instead of taking the chamber apart over the sink. Nutribullet states one on its slow juicer; AMZCHEF states one on the ZM1501.
2. 2.Adjustable pressure or a second screen, which lets you reduce back pressure for soft produce instead of forcing it through a fine mesh. Omega states five adjustable end-cap pressure settings and two juicing screens on the NC900HDC -- the only machine on this site with both.

The Omega NC900HDC is the one we would buy if the shopping list is unpredictable: five published pressure settings, two screens, 80 RPM, 150 W and a 15-year limited warranty. The Nutribullet Slow Juicer and the AMZCHEF ZM1501 both publish a reverse function, which is the single most useful feature when something wraps the screw -- at $100-200 and under $100 respectively.

Soft fruit deserves its own warning

Berries, peaches, mango and banana are the produce people most often buy a juicer for, and the produce a juicer is worst at. Berry skins and seeds pack into a screen rather than being carried away as pulp, a banana yields essentially nothing, and mango has very little free liquid. None of it damages the machine; all of it disappoints.

If soft fruit is the plan, a blender is the correct appliance and no juicer is a substitute. Best juicers for berries makes that argument at length, and juice vs smoothie is the appliance decision.

For the things that are worth juicing and how to prepare each one, juicing for beginners is the starting point, and best juicers for vegetables covers the machine side.