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Cellar Operations · 7 min read

Must & Juice Handling Equipment Guide

Moving must and juice well comes down to three decisions: a pump that handles solids without macerating them, lines wide enough to keep the flow slow, and a layout that limits drops, splashing, and air pickup. A must pump — usually a peristaltic or a large-bore positive-displacement unit — is the core of the setup, but the hoses, fittings, and how you route them decide whether the wine arrives intact or stressed.

This guide covers what counts as "gentle," which pump types suit must versus clarified juice, how to size lines, and the practical mistakes that quietly add bitterness and oxygen at the start of every vintage.

What "gentle" actually means at crush

Gentleness is not one thing. Three separate stresses act on must and juice as they move:

• Shear and maceration — mechanical tearing of skins, seeds, and pulp that extracts harsh phenolics and can grind seeds into the must. The faster a pump spins and the tighter its internals, the more shear.
• Oxygen pickup — air drawn in through suction leaks, splashing, free-fall into a tank, or pulsation. White juice is especially sensitive before any protective additions are made.
• Crushing of intact berries — when you want whole or partial berries to reach the tank unbroken (for example, feeding a fermenter for carbonic or semi-carbonic work), the transfer must carry them without bursting them.

A handling setup is "gentle" when it addresses all three, not just one. A pump can be low-shear yet still aerate badly because of a bad fitting or a long free-fall at the tank top.

Matching the pump to what you're moving

The right pump depends on solids load. Crushed-and-destemmed red must, free-run white juice, and pressed juice with fine lees are three different duties.

Crushed must with skins and seeds

This is the toughest transfer in the cellar. The standard answer is a large-bore peristaltic must pump: rollers squeeze a wide food-grade tube, moving must in sealed pockets with no internal contact, no internal slip, and minimal seed grinding. Flow reverses easily to clear blockages, and speed control lets you slow down for fragile lots. Lobe and certain progressive-cavity pumps also move must, with their own trade-offs in cost and cleaning.

Free-run and pressed juice

Clarified or lightly turbid juice is far more forgiving. A peristaltic still works and adds almost no oxygen, but a flexible impeller pump run slow or an air-operated diaphragm pump can be enough for routine clean-juice moves. For a side-by-side of the common transfer pumps, see the wine pump comparison.

Whole or partial berries

If you want berries to arrive intact, slow positive-displacement movement with very wide bore, or gravity feed, beats any high-speed pump. Some cellars avoid pumping berries entirely and rely on elevation instead — see the trade-offs in the broader winery pumps guide.

Must pump types at a glance

Buying education only, not engineering advice — confirm duty ratings, materials, and solids tolerance with suppliers before purchase.

Sizing lines and fittings for slow flow

The pump gets the attention, but line diameter often does more for gentleness. Wider hose carries the same volume at a lower velocity, which means less shear, less turbulence, and less chance of clogging on skins and stems.

Practical principles:

1. Match the hose bore to the pump's inlet/outlet — necking down to a smaller fitting forces velocity up at exactly the wrong point and invites blockages on must.
2. Keep suction runs short and airtight — most oxygen pickup on the inlet side comes from loose camlocks or tri-clamps drawing air, not from the pump itself.
3. Use the widest practical bore for must — narrow lines that are fine for clean wine choke on crushed red must.
4. Minimise sharp bends and long verticals — every elbow and lift adds back-pressure and a spot for solids to pack.

Food-grade hose and sanitary fittings rated for the duty matter as much as the pump. A matched transfer hose kit or food-grade wine hose kit keeps bore, material, and fittings consistent. For the wider picture on hoses, gaskets, and connection standards, see the wine transfer equipment guide.

Controlling oxygen and splashing

Even a perfect pump can aerate juice through the destination. The fixes are low-cost:

• Fill from the bottom, not the top — a drop tube or bottom-fill valve avoids free-fall splashing into the tank.
• Slow the flow at the start so the first juice doesn't splash against the tank floor.
• Check every gasket on the suction side — a single tired seal pulls air for the entire transfer.
• Dampen pulsation on diaphragm pumps with a dampener or lower air pressure if you're moving sensitive white juice.

Whites generally need tighter oxygen control than reds at this stage; reds are protected later by skin contact and fermentation. For the equipment angle on managing dissolved oxygen across the cellar, see oxygen management equipment.

Fitting must handling into the crush pad

Must and juice handling is part of crush-pad flow, not a standalone choice. The pump has to reach from the crusher-destemmer to the fermenters with hose runs that don't cross walkways or force tight bends. Decisions about gravity versus pumping, hopper height, and tank placement all interact — plan them together using the crush pad planning guide.

The same pump that feeds fermenters at crush often does double duty for racking and pumping over later in the season, so buy for the hardest job it will face, not just the easiest. If you're also choosing the crusher-destemmer that feeds it, the crusher-destemmer selection guide covers throughput matching.

FAQ

What is the best pump for moving grape must? A large-bore peristaltic pump is the common benchmark: it moves crushed must and even whole berries in sealed tube pockets with minimal seed grinding and very low oxygen pickup, and it reverses to clear blockages. Lobe and progressive-cavity pumps also handle must, usually at higher cost and with more cleaning.

Can I use one pump for must and clean wine? Yes — a peristaltic or progressive-cavity pump that handles must will also move clean wine and juice gently, which is why many cellars buy one capable pump rather than two. A flexible impeller pump, by contrast, suits clean juice only and should not be used for crushed must.

How do I stop juice from oxidising during transfer? Keep suction lines short and airtight, fill tanks from the bottom to avoid splashing, slow the initial flow, and check every gasket on the inlet side. Most oxygen pickup comes from air leaks and free-fall, not the pump itself. Whites need the tightest control before protective additions.

Does line diameter really affect must handling? Yes. Wider hose moves the same volume at lower velocity, which reduces shear and the risk of clogging on skins and stems. Necking down to a smaller fitting at the pump outlet is a common cause of blockages and unnecessary maceration on red must.

Bottom line

Choose a must pump for the toughest job it will face — usually a large-bore peristaltic for crushed must — then back it with wide, well-matched lines and a fill method that avoids splashing. Gentleness is the sum of pump, line size, and layout, not any single component.

Put the candidates side by side: compare must pumps and transfer gear on wine.equipment by flow rate, solids handling, and bore before you request supplier quotes.

Related on wine.equipment

• Compare machines side by side
• Browse wine transfer equipment
• Winery Pumps 101: Wine Pump Types Compared
• Peristaltic vs Impeller vs Diaphragm Wine Pumps
• How to Choose a Crusher-Destemmer: Buying Guide
• Wine Transfer Equipment: Hoses, Pumps & Fittings Guide
• Crush Pad Planning: Layout, Utilities & Flow
• Oxygen Management Equipment for Wineries

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