When winemakers are getting ready to buy a commercial press, figuring out what size press to buy can be really confusing. How many one-ton bins of fresh white grapes will fit inside a 12 hectoliter press? What about destemmed grapes? There are some practical and historical reasons for the confusing nomenclatures around sizing, and we’ll attempt to explain some of them, as well as strategies for thinking about sizing your press.
In the US we typically talk about wine grapes in terms of “tons”. We’re putting “tons” in quotation marks because it’s not a ton in the truest sense. A real ton is a measure of weight. It’s 2000 pounds. However, when we talk about a “ton of grapes”, it’s more likely that we’re referring to its volume—how much space it takes up. That’s because wine grapes are often sold, harvested, and processed in macro bins that are casually referred to as “half-ton” or “one-ton” bins because their load capacity is 1000 pounds or 2000 pounds, regardless of the actual weight of the grapes they contain. The weight of the grapes is, in fact, mostly irrelevant.
The most common bin we see referred to as a “one ton bin” is the Probin 44-S manufactured by Macro (hence why they are sometimes also called “Macro Bins”). The Probin 44-S has a volumetric capacity of about 240.7 gallons.
The Field Ton
A “Field Ton” refers to both the volume of some amount of grapes as well as how those grapes will be processed. Let’s use a simple example and imagine you have one “ton” of Pinot Noir grapes. In reality, you have a one ton bin of whole cluster Pinot Noir grapes. Its weight is irrelevant, and is almost certainly not 2000 pounds. All you want to know is what size press that one “ton” of Pinot grapes will fit in once you’re done processing it.
The typical workflow for Pinot grapes is to destem them, partially crush them (optional), and allow them to ferment for some time before pressing. After fermentation, any free-run juice is pumped out. This leaves behind just the wet fermented must for pressing. The volume of grapes you’re left with is quite a bit less than what you started with. In all likelihood, the volume is now just under 95 gallons, or about 350 liters. If you were looking for the ideal press to hold what you’re left with, you’d end up at the Mori PZ 70. In fact, we call the PZ 70 a one-ton press. One ton of red grapes from the field goes right into it after processing. This is where the term “field ton” comes from.
So you start with a one ton bin of grapes that has a volume capacity of about 241 gallons and you end up with about 92.5 gallons. 92.5 divided by 241 is about 3/8. Thus, we can say that a field ton of fermented red grapes is about 3/8 its original volume before processing. As noted previously, every grape varietal is different and every harvest is different, so the numbers we talk about here are approximate. Still, it gives us somewhere to start.
Meanwhile, in Europe the more common unit for volume is actually a real unit of volume. How refreshing! Europeans measure grape volumes in hectoliters (HL). One HL = 100 liters. Since many presses are made in Europe, their volume is often denoted in HL. If you want to follow along while still using tons as your default unit of measure, just know that a one-ton bin has a volume of 240.7 gallons, which equals about 911 liters, or 9.11 HL.
Some Calculations for Press Size
Fresh Whole Cluster Grapes
If you’re pressing fresh, whole cluster grapes, your press capacities are pretty straightforward. To press a one-ton bin of fresh whole cluster grapes, you’ll need a 10 HL or larger press. 10 HL = 264 gallons, and a one-ton bin has a capacity of about 240.7 gallons, so it just fits in a 10 HL press.
With that knowledge, just multiply 10 HL by however many one-ton bins you’re processing, or how many one-ton bins you want to process in a single pressing. For example, to process two bins at a time, you’ll need a 20 HL press.
Destemming grapes reduces their volume by about 1/4. So assuming you started with a one-ton bin (240.7 gallons), your volume is now 180 gallons. 180 gallons = 681 liters = 6.8 HL, so you’d need a 7 HL press to fit a one-ton bin of destemmed grapes. 14 HL would fit two bins, and so on.
As noted above, processing reduces the original volume of red grapes by about 5/8. After a one-ton bin is destemmed, crushed, fermented and had any free-run juice pumped out, you’re left with about 92.5 gallons, which is equal to 350 liters = 3.5 HL.
Hopefully these figures give you a good starting point when considering the size of your press. In an ideal world you’d have a Sraml Pneumatic Membrane Press for efficiently extracting juice from fresh white grapes or whole clusters, and a Mori Basket Press for gentle and efficient pressing of fermented reds like Pinot. In reality, though, you may have to make do with one press for all varietals as you grow and expand, so give us a call if you have questions about sizing the right press for your facility.