Press cycles on a basket press

Anyone have press cycle programs on their basket press?

Do you have a specific amount of pressure you consider to be your sweet spot and if so, which varietal are you pressing?

Carlsen and Associates has a freebie program on their site and we’ve been experimenting but I was wondering what worked for others.

I have a older wooden slatted basket press that is a Marzolla from Spain. It can fit about 2.5 tons of whole cluster white and about 6 tons of red skins. It progressively builds pressure up to 2 set points and the 3rd stage is as hard as it can go.

I prefer to hang out during the cycle of about 1-2 hours and taste every few minutes to make the cut. I use some whole clusters and only work with PN for reds. Up here in AV we have variable berry size and skin thickness compared to what I have seen to the south of us in Sonapa. I think making the press cut by taste is a great equalizer of vintages in regards to the tannin extraction were looking for headed to barrel.

For example in a year like 2011 with larger thin skinned berries and only 10% whole clusters I pressed as hard as it would go. In a year like 2014 with small berries and 50% whole cluster inclusion I did not press as hard. In 2011 the PN I make that gets new oak also got more, in 2014 I used less new oak as there was more stem tannin present. Were on the skins for 21-30+ days, press at cap fall, native ferments, no temp control.

Most folks talk in bars for bladder/membrane presses. I can only guess those numbers based on gallons per ton. For the pressure set points on mine its measured pressure of the hydraulic lines in bars. First stop is 40 for 18 minutes, second is 80 for 45 minutes, max is 220 or 240 as I recall. It takes quite a while to hit the first stop, and usually when it heads to the second I start to taste some of the whole berries start to burst. The last few vintages (drought, small crop of small berries, 30-50% whole cluster) I cut it before it hits the second stop.

Our basket press doesn’t have a PLC or automation just variable set points based on pressure. It is a smaller press, holds about 1.5 tons worth of fermented skins with a fairly high percentage of whole berries. The typical routine is 100 bar as the first set point and hold there until the flow starts to drop. Then 150, pause for flow to drop, then 200 bar max. It will go all the way to 350 bar but I haven’t found that to produce much more juice and quality goes down. I kept track during a Zinfandel pressing of quantities at various stages -
Free run, pumped off - 225g
Press at 0 bar - 30g
Press up to 200 bar - 25g
The 0 bar amount is simply the head coming down prior to any back pressure registering on the gauge. So only 10% was actually pressed with any force. I would guess that pushing full pressure wouldn’t yield more than about 5 more gallons on 1.6 tons of picked fruit.