maximum extraction when pressing whites

[winemaker81]

I read an article this morning on WineMakerMag regarding maximizing extraction from white grapes. The article is a members-only, so if you don't have a membership you won't be able to read it.

https://winemakermag.com/wine-wizard/pressing-issues
The article mentioned adding rice hulls, which has been discussed on WMT. It also mentioned leaving 1/3 of the stems in, to create paths for the juice to run, but cautioned to not leave the stems in for too long, to avoid excessively tannic wine.

Freezing is an idea, but is feasible only if making a small batch OR if there is access to a walk-in type freezer. Cold soaking is dismissed as it produces "orange wine" (not the term used).

The idea that caught my attention is maceration enzymes. I use them for reds, but have no idea how quickly they break down structure, as I soak 24 hours, inoculate, then ferment for a week or so.

Has anyone used maceration enzymes with whites, and if so, how long did you let the crushed grapes soak before pressing?

 

[cmason1957]

This year I did about 150 lbs of La Crescent white grapes at a local friends vineyard. They were planning to harvest, but not make wine this year due to age of the winemaker and no support from children. My wife and I picked them early Sat. morning, crushed, but not destemmed. We wee offered the crusher/destemmer or just a crusher, whichever we wanted to clean up. I had used their crusher/destemmer on other occasions and didn't feel it took out enough to make the extra clean-up worth the effort. We drove them home (hour drive) then added pectic enzymes when we got home, poured the buckets together. Normally, I would have pressed soon thereafter, but my wife and i had tickets to go see a comic that evening, so into the fridge to cold soak overnight. Next morning we pressed. Out of our 140 we got about 10-11 gallons of white juice to ferment. We also added about 1/2 gallon of water after the press to the pressed stems, etc and forked the wine and repressed somewhat. This was a step the winemaker suggested to help tone down the flavors just a bit and to get more apparent juice out of the pressing.

If anyone cares D47 yeast, a bit of bentonite and fermented sitting on my basement floor under airlock.

It is now sitting in carboys. It has been racked twice, already starting to clear, somewhat. Down to about 10 gallons after the first two rackings. Taste is raw, but showing promise, the nose, so far is wonderful tropical fruits.

Time will tell. Based on information from the winemaker, it takes a good year or two for this wine to come around.

 

[VinesnBines]

This is timely because I'm making out an order to More Wine for yeast, enzymes and the like. I may macerate/cold soak my Traminette for 24 to 48 hours on the skins and maybe the Chardonnel. I hadn't thought of extraction enzymes and Opti white for white grapes. I need to research the use of rice hulls.

Thanks again Bryan!

 

[winemaker81]

I may macerate/cold soak my Traminette for 24 to 48 hours on the skins and maybe the Chardonnel.

I'm leery of too long a cold soak, to avoid color and tannin extraction. So far I haven't found anything solid regarding "how long".

 

[VinesnBines]

There's the rub. For me it may be as time/circumstances dictate. Like Craig, an overnight soak may be necessary or alternatively if pressed for time, not practical.

 

[Cynewulf]

Last year I crushed, destemmed, and immediately pressed 85% of my Itasca and macerated the remaining 15% for a week before blending and aging them together for 9 months. I go with ambient yeast, no added sulfites, unfiltered. These aren’t the best photos, but the color came out clear and golden (the second photo looks a little cloudy from the condensation on the glass). The wine has a nice body, with some unusual flavors of apple, pineapple, honey, and curry spices on the finish. My wife really likes it which is the important metric for me.


This year, I macerated 90% for 24 hours to improve the extraction and the other 10% for 7 days before blending together.

 

[Maheesh]

CMASON, did you leave the bentonite in during fermentation?

 

[balatonwine]

It also mentioned leaving 1/3 of the stems in, to create paths for the juice to run, but cautioned to not leave the stems in for too long, to avoid excessively tannic wine.

I crush and immediately toss it all, including the stems, into the press. I get no excessive tannins. This fear of tannins from stems I have been developing the opinion that is more a repeated myth from poor wine winemakers than an actual really important and relevant issue. Maybe more an issue of using too much pressure to squeeze out every little drop of wine is the problem. Not the stems per se. Light press and live with less wine. That is what I do.

So contrary to the topic: I do not try to get maximum extraction. I try to get maximum quality wine. Quality over quantity.

But I can get quite a bit of extraction using the press, pause, press, pause, press pause, etc. method. That is, press lightly. When the pressing gets a little hard, stop. Wait 5 or 10 minutes. Come back and you will find you can press easily again and get a lot more juice. Repeat until the juice flow is not improved after the pause. To get even more, remove the press cake from the press, put it into a container. "Fluff" it. Let it rest 4 to 6 hours. Put back in the press. And you will get even more juice.

Cold soaking is dismissed as it produces "orange wine" (not the term used).

Nonsense. Cold soaking is a short time issue. Before fermentation starts. Often after KMeta was added and before yeast is added. Often as little as 4 or up to 24 hours. It can aid in additional extraction. It does not create an orange wine, or any term the article may have used. To create an orange wine you have to ferment on the skins. Different process. But if you cold soak you have to first remove most or all the stems. The authors may be biased and not liked the wine created from cold soaking... but maybe you may like it even better than you may expect. Tastes differ. Do not be afraid to experiment.

Get a copy of "From Wines To Vines". Excellent discussion of the pros and cons of cold soaking (I think you can even find some of the text online if you search for it). But definitely not making orange wine. Completely different issue and process. I have done both. So I know the results of each. I stopped doing cold soaking as I did not find it gave many benefits. But I certainly do more and more orange / amber wine making these days.

how long did you let the crushed grapes soak before pressing?

I crush to fill about about 250 liters, then press. The grapes soak as long as it takes me to crush 250 liters. So some grapes soak for maybe 5 minutes or 20 minutes. Or else they continue to soak and are made into Amber wine.

Hope this helps.

 

[cmason1957]

CMASON, did you leave the bentonite in during fermentation?

Like a wine kit, I added it about two days into fermentation (because I forgot to add it sooner) and left until fermentation was nearly complete.

 

[winemaker81]

I screwed up when writing the first post, as the author of the article described browning, not orange wine. I have NO idea how that popped out of my fingers.

I crush and immediately toss it all, including the stems, into the press. I get no excessive tannins. This fear of tannins from stems I have been developing the opinion that is more a repeated myth from poor wine winemakers than an actual really important and relevant issue.

The point you're missing regarding stems is time. You crush and immediately press, so there is no extraction of tannin from the stems. Cold soak the grapes for 24 to 72 hours, and it's a apparently a different story. The story in the article indicates a winery cold soaked Riesling for 3 days, and produced a light brown, tannic wine.

Cold soaking of whites is not an area I would investigate. From what I've read there is no benefit and certainly drawbacks, and I wouldn't waste the grapes.

But I can get quite a bit of extraction using the press, pause, press, pause, press pause, etc. method. That is, press lightly. When the pressing gets a little hard, stop. Wait 5 or 10 minutes. Come back and you will find you can press easily again and get a lot more juice. Repeat until the juice flow is not improved after the pause. To get even more, remove the press cake from the press, put it into a container. "Fluff" it. Let it rest 4 to 6 hours. Put back in the press. And you will get even more juice.

I do this when pressing reds, post-fermentation. I purchased a second pitchfork that is used only for wine, and break up the cake, then press again.

 

[balatonwine]

I screwed up when writing the first post, as the author of the article described browning, not orange wine. I have NO idea how that popped out of my fingers.

Ah.... We all have demon fingers at times. Totally understand.

The point you're missing regarding stems is time. You crush and immediately press, so there is no extraction of tannin from the stems. Cold soak the grapes for 24 to 72 hours, and it's a apparently a different story. The story in the article indicates a winery cold soaked Riesling for 3 days, and produced a light brown, tannic wine.

Well.. Actually, I did not miss the point. And if I cold soak, or make amber wine, I remove the stems. And, as I wrote, I have done cold soaking. ("I have done both." when referring to cold soaking and amber wine making).

But I also said that cold soaking is a limited process. That is, I wrote "up to 24 hours". Cold soaking often is less than 24 hours. If one is soaking for 72 hours, as in this article, that is a different game. And they should not call it "cold soaking". In that time frame they are entering amber wine production.

Hope this helps.

 

[balatonwine]

in the article indicates a winery cold soaked Riesling for 3 days, and produced a light brown, tannic wine.

Side note: Different wines need or can tolerate different wine making methods in the cellar.

Riesling is not an ideal wine to cold soak.

In fact, I would never cold soak a Riesling. That would be, IMHO, stupid. This is one of the the worst grapes to cold soak. You get no benefits, and only cause problems.

Beware extrapolating a bad experiment, on the wrong wine, to all wine varieties. Just saying....

 

[winemaker81]

Beware extrapolating a bad experiment, on the wrong wine, to all wine varieties. Just saying....

Such things make me cautious.

 

[balatonwine]

Such things make me cautious.

In the current miss-information climate I do not trust anyone but me, myself and I.

And even then, I only trust me, myself and I half of the time.....

 

[wood1954]

Last year I crushed, destemmed, and immediately pressed 85% of my Itasca and macerated the remaining 15% for a week before blending and aging them together for 9 months. I go with ambient yeast, no added sulfites, unfiltered. These aren’t the best photos, but the color came out clear and golden (the second photo looks a little cloudy from the condensation on the glass). The wine has a nice body, with some unusual flavors of apple, pineapple, honey, and curry spices on the finish. My wife really likes it which is the important metric for me.
View attachment 91784
View attachment 91786
This year, I macerated 90% for 24 hours to improve the extraction and the other 10% for 7 days before blending together.

glad to hear your itasca turned out good. Ive got 10 plants 3 years old with a few pounds on them. They taste very good now, hope to add them to some marquette to make a rose this year and a white winem next year.

 

[BRossi]

I also have 10 Itasca vines that are 4 years old this year and should produce enough for harvest this fall. This will be my first attempt at white wine. Up to now, I have not used a press. I was interested in a bladder style press for ease of clean up, etc. The ones I’ve seen are around a $1000. What are people using to press white grapes? even the wooden press is over $500.

 

[balatonwine]

I also have 10 Itasca vines that are 4 years old this year and should produce enough for harvest this fall. This will be my first attempt at white wine. Up to now, I have not used a press. I was interested in a bladder style press for ease of clean up, etc. The ones I’ve seen are around a $1000. What are people using to press white grapes? even the wooden press is over $500.

I mainly make white wine. I have three wood presses. Different sizes. For use with different amounts of grapes to be pressed. So I calculate as needed. So you should also (i.e. do not buy too large a press for your needs).

Thus, be aware that a basket press can be multi-loaded. That is, I fill the press, press, remove the press plates add more must, press, etc and repeat. I get about three pressings before I have to disassemble and clean a press**. The first press, leaves about 50% of the volume to be reloaded. The second press leaves bout 30% to be reloaded

But this is for my vertical basket presses. Horizontal bladder presses may have different capacities and ability to reload. I have less experience with bladder presses so others should be consulted.

** I use a pressure washer, so cleaning is rather easy. What is not so easy is hefting the wood press baskets for my very large #55 press, but my smaller presses this is not an issue and easy to do.

 

[BarrelMonkey]

Thus, be aware that a basket press can be multi-loaded. That is, I fill the press, press, remove the press plates add more must, press, etc and repeat. I get about three pressings before I have to disassemble and clean a press**. The first press, leaves about 50% of the volume to be reloaded. The second press leaves bout 30% to be reloaded

Huh... I never considered doing this, I always just empty out the pomace after the first press and start over. (But I don't wash, pressure or otherwise between pressings, as long as I'm processing the same batch of grapes). I wonder if there are advantages/disadvantages either way eg does reloading on top of already pressed grapes decrease efficiency and/or lead to more extraction from seeds/skins? Or maybe double/triple loading is more efficient? Washing or no it would be nice to not have to break down and reassemble the press so many times...

 

[wood1954]

I use a nylon bag in my press and empty it after every time I load and press. I don’t have a picture of the bag in it. The bags are usually a laundry bag with larger mesh and usually only last for one day’s pressing.

 

[balatonwine]

Huh... I never considered doing this, I always just empty out the pomace after the first press and start over. (But I don't wash, pressure or otherwise between pressings, as long as I'm processing the same batch of grapes). I wonder if there are advantages/disadvantages either way eg does reloading on top of already pressed grapes decrease efficiency and/or lead to more extraction from seeds/skins? Or maybe double/triple loading is more efficient? Washing or no it would be nice to not have to break down and reassemble the press so many times...

Multi-loading of basket presses is a thousands year old tradition. That is what improves efficiency, at least in pressing time, of this press type.

As for your other questions, that has been researched :
https://ifst.onlinelibrary.wiley.com/doi/epdf/10.1111/jfpp.16707

Utilization of the basket press method to extract verjuice​

Ali Hajiahmad, Amir Hossein Mirzabe

Abstract​

In this study, two cylinders were used as the main part of the basket press. Berries were poured into the cylinders and were subjected to compression force. Loading rate, layer height, number of layers, and cylinder diameter were considered operating factors. Force–deformation data were recorded. At the end of each test, the mass of extracted juice was measured. Extraction Yield of Juice (YOP), pomace density, Specific Absorbed Energy by Berries (SAEB), and Efficiency Index of Energy (EIE) were output variables. Analysis of variance and optimization were performed. The operating parameters on YOP and SAEB were effective at a significance level of p-value < .01. Moreover, the EIE was significant under the effect of all inputs at 5%. YOP and SAEB ranged from 23.42 to 43.10% and 192.23 to 255 J kg−1, respectively, for basket 1. The corresponding values for basket 2 were 11.07 to 27.81% and 53.53 to 84.01 J kg−1, respectively.

Novelty impact statement​

The basket press method helps to maintain the quality of the juice because by applying the controlled pressure, the bitter seeds of the unripe grape berries can be prevented from being crushed and the bitterness transferred to the juice. The pressure on the berries was increased to the point that the quality of the extracted verjuice did not decrease. Effects of loading rate, layer height, and the number of layers are significant on the performance and efficiency of the method.