When to press

[CDrew]

I have two wines at 5 brix, was hoping to press today. They've been on the skins for 17 days so that should be plenty long enough. By what I'm reading here it won't do any harm to press today, is that correct?
Actually, I thought of a possible scenario. Ferment has been slow due to cool temps, not complaining. But what if it gets stuck? It would be easier to work with in the primary, no?

I agree, it might be a bit early, What is the true brix? The highest I've pressed at is +4 and it finished OK. But in general, I'd get closer to dry. You are right that dealing with a stuck ferment will be easier while still in the fermentor. Good luck.

 

[winemaker81]

Correct, I guess my point being that you don't need to ferment to dry on the skins like you would if using a kit. It will get to dry during the Mlf stage.

I can't refer to my own experience on the subject, but numerous respected members of WMT have reported successful co-inoculation. AFAIK, you can inoculate with MLB at any point you desire.

 

[meridaen]

I would never press on taste, more on time spent on skins, the data, and my life schedule, in that order. Taste is profoundly dependent on our neurophysical environment at the time and how it influences our mind/sensory interface, how you are feeling and your physical state will so easily overpower anything that is in your must. Taste being based purely on what is in our mouth is just a story we tell ourselves, and using that alone to choose when you do anything in the winmaking process is akin to oenological astrology IMO.

 

[SLM]

Hydrometer vs refractometer? True brix? Please explain more.
My SG is at 1.020

 

[sour_grapes]

Hydrometer vs refractometer?
My SG is at 1.020

What instrument did you use to determine this?

 

[winemaker81]

Hydrometer vs refractometer? True brix? Please explain more.
My SG is at 1.020

A refractometer accurately measure the brix in unfermented juice or grapes. However, during fermentation, as the amount of alcohol goes up, the accuracy of the reading decreases, since alcohol weighs less than water. There is a conversion to translate the inaccurate brix reading into a supposedly accurate SG reading.

A hydrometer measures specific gravity, the density of a fluid with respect to water (SG 1.000). The SG indicates the relative location in the fermentation process, and at the end of the process the reading enables the winemaker to make a judgment call when fermentation is complete without using a translation.

 

[SLM]

The longer I do this, the more complicated it gets!

I use hydrometers. On the scale, 5 brix = about sg 1.020. I just like to use the brix scale because it's 2 digits as opposed to 4, less computing for my brain. Is brix on a hydrometer not accurate? Whatever the number, we are not close to dry yet. We decided to put off pressing for a couple days.

 

[hawkwing]

The Italian guy I got my grapes from said to press in the first week otherwise there would be too much tannins. But he also told me to leave more stems in. Probably more to the style he’s used to. I let it go dry as was told on this forum. Also had lots to do with my schedule too.

 

[winemaker81]

I use hydrometers. On the scale, 5 brix = about sg 1.020. I just like to use the brix scale because it's 2 digits as opposed to 4, less computing for my brain. Is brix on a hydrometer not accurate? Whatever the number, we are not close to dry yet. We decided to put off pressing for a couple days.

Few of the frequent posters use Brix after fermentation starts. The brix scale on the hydrometer is correct -- before fermentation. This question has not arisen before, but I assume the hydrometer will report false Brix, same as a refractometer. Note that while the Brix reading on the hydrometer does correspond to the SG reading, the meaning of the Brix is incorrect -- 2 Brix doesn't mean there is 2% sugar remaining -- IIRC, it's actually zero.

The Italian guy I got my grapes from said to press in the first week otherwise there would be too much tannins. But he also told me to leave more stems in. Probably more to the style he’s used to. I let it go dry as was told on this forum. Also had lots to do with my schedule too.

He is correct -- if the stems are left in, a short fermentation prevents the extraction of too much tannin. Yeah, different style of winemaking.

 

[CDrew]

The longer I do this, the more complicated it gets!

I use hydrometers. On the scale, 5 brix = about sg 1.020. I just like to use the brix scale because it's 2 digits as opposed to 4, less computing for my brain. Is brix on a hydrometer not accurate? Whatever the number, we are not close to dry yet. We decided to put off pressing for a couple days.

I find brix scale much more intuitive and easier to work with too, Thanks for confirming that you are using a hydrometer. Someone had suggested you might be using a refractometer. Brix vs specific gravity is a subjective choice, but most commercial guys use brix. For me on my full scale hydrometer the brix scale is easier to see so I use that, and on my +5/-5 hydrometer, it's only in Brix, thus making the choice easy! When I was making beer 20 years ago, we always used SG!

Regarding when to press, I've (fortunately) never had a stuck fermentation, and have pressed at 4brix for convenience but I like to press around 0 or below.

And @winemaker81 the hydrometer will not report anything false. There is a direct consistent relationship to SG. It's just easier to use. And just like the SG scale, -brix is analogous to SG below 1.000.

 

[winemaker81]

And @winemaker81 the hydrometer will not report anything false. There is a direct consistent relationship to SG. It's just easier to use. And just like the SG scale, -brix is analogous to SG below 1.000.

Nope. Brix is a measurement of sugar, and as fermentation progresses, the reported value is increasingly wrong. 2 Brix at the end of fermentation is inaccurate -- there is not 2% sugar remaining.
See @sour_grapes's post (#34) below, as he identified my error.

The difference is that you know what it means, and mentally translate. For less experienced folks, the common question is, "why is my ferment stuck at 2 brix?" when it's not actually stuck -- it's done.

I agree that SG takes more effort to measure, but IME it's easier to explain to beginners and to have them understand.

 

[CDrew]

Nope. Brix is a measurement of sugar, and as fermentation progresses, the reported value is increasingly wrong. 2 Brix at the end of fermentation is inaccurate -- there is not 2% sugar remaining.

The difference is that you know what it means, and mentally translate. For less experienced folks, the common question is, "why is my ferment stuck at 2 brix?" when it's not actually stuck -- it's done.

I agree that SG takes more effort to measure, but IME it's easier to explain to beginners and to have them understand.

I'm not sure what to make of this. Maybe I did not explain well. 0 brix and SG 1.000 are the same. Fermentation when finished shows a brix between -1 and -2 (note the negative sign), 2 brix would not be complete and stuck in your example above. If you read my comment #30 carefully, note I specified (negative) brix.

And brix goes negative for the same reason SG goes below 1.000; ie that the solution now contains alcohol which is less dense than water.

 

[winemaker81]

I'm not sure what to make of this. Maybe I did not explain well. 0 brix and SG 1.000 are the same. Fermentation when finished shows a brix between -1 and -2 (note the negative sign), 2 brix would not be complete and stuck in your example above. If you read my comment #30 carefully, note I specified (negative) brix.

Nope -- you are explaining fine. I am not.

Please note that I'm using the literal meaning of Brix, which is the percentage by weight of sugar in a liquid. There is literally no such thing as "negative brix" as it's not possible to have a negative amount of sugar. The negative values on a hydrometer are an extrapolation of the brix scale, and do not exist in reality.

This is not to say the negative values have no use -- as a user of the brix scale as presented on a hydrometer, the negative values are meaningful to you, and enable you to make the same decisions I do with SG. There is no difference in the outcome -- we reach that outcome using different paths.

This is yet another good discussion, as I now know more about SG and Brix than I did a few days ago.

 

[sour_grapes]

but I assume the hydrometer will report false Brix, same as a refractometer.

Bryan, the problem with using a refractometer after fermentation is NOT the same problem as reading Brix from a hydrometer. In fact, those problems have a different sign!

Alcohol affects two things: It affects the density (as you know), and it affects the index of refraction. Alcohol decreases the density, but it increases the index of refraction. In contrast, sugar increases both the density and the index of refraction.

Thus, on a hydrometer, the presence of alcohol makes it look like there is less actual sugar than there is. On a refractometer, the alcohol makes it look like there is more actual sugar than there is.

 

[winemaker81]

Bryan, the problem with using a refractometer after fermentation is NOT the same problem as reading Brix from a hydrometer. In fact, those problems have a different sign!

Thanks for the correction. I modified my post (#31).

 

[distancerunner]

Is this the reason we look for negative numbers, <1.000 SG or -5° Brix for instance, on a hydrometer instead of zero?

 

[sour_grapes]

Is this the reason we look for negative numbers, >1.000 SG or -5° Brix for instance, on a hydrometer instead of zero?

Yes, assuming you meant "<1.000," not ">". The alcohol lowers the SG to less than 1.000.

 

[distancerunner]

Yes, I did.

Sorry.

Edited.

Thank you.

 

[winemaker81]

Is this the reason we look for negative numbers, <1.000 SG or -5° Brix for instance, on a hydrometer instead of zero?

Some SG-to-Brix tables include negative brix values when the SG is < 1.000. Others list all SG values of 1.000 or less as equating to 0 brix. While accurate, this is not useful to a winemaker.

 

[CDrew]

I just thought you might be interested in the business end of my finishing hydrometer. +5/-5. Obviously all hydrometers only read density. The negative #s may not be strictly real, but they are very useful at the end of fermentation. The scale is just being projected to account for the fact that the wine is less dense than water due to alcohol at the end of fermentation.