Grapefest 2010 Ferments

[goldseal]

I agree completely... it is great. I use it religiously!

And I think there is a "make tea" button somewhere there.

Still can't find that button

I still like to do the calcs manually, just so I keep in practice and actually understand what I'm doing, then use FermCalc to confirm my numbers.

[lockwood1956]

I adjusted the acidity on the Trebbiano, adding it in three stages, it required all 385 grams, and acidity now stands at 7 g/l exressed as tartaric

measured thye merlot (tricky as it is very dark) and I get it to 6.5 g/l expressed as tartaric

Ferment is underway today, punched the (small) cap this morning

[solly]

I dont have an Acid test kit, but looking through the posts the average seems to be 5.3 for the Merlot and 5.8 for the Monte (expressed as Tartaric).

So for a 5 gallon batch (22.5 lts) you would need 112gms of Tartaric Acid?
And for a 1 gallon batch (4.5 lts) you would need 22gms of Tartaric Acid?

I assume that you could use the same amount for both the Merlot & the Monte as the figures as about the same for both?

Do these figures seem about right? Going to buy a test kit anyway, but it might be handy for those that dont have a test kit. (If I am looking at the right thing then they seem to be about 6 quid for the test kit).

[goldseal]

That looks a bit too much.

It depends what acidity you are aiming for. I'd say somewhere in the 6.5 - 7 range. Let's aim for 6.5, because we can always add more acid later, but it is a bit trickier taking it out.

If the must is currently at 5.3 we need to add 1.2 grammes per litre. 1.2 x 22.5 = 27 grammes (in 22.5 litres).

If your Monte is at 5.8, you only need 0.8g per litre, which is a total of 18g.

[solly]

That looks a bit too much.

It depends what acidity you are aiming for. I'd say somewhere in the 6.5 - 7 range. Let's aim for 6.5, because we can always add more acid later, but it is a bit trickier taking it out.

If the must is currently at 5.3 we need to add 1.2 grammes per litre. 1.2 x 22.5 = 27 grammes (in 22.5 litres).

If your Monte is at 5.8, you only need 0.8g per litre, which is a total of 18g.

OK thanks Pete..I understand it now, if my reading was 4.5 and I want to up to 6.5 then its a matter of adding 2gms to take the reading upto 6.5

(I got confused as I was reading were Bob was adding 5g/L to his must, thanks for putting me stright)

[NorthernWiner]

OK thanks Pete..I understand it now, if my reading was 4.5 and I want to up to 6.5 then its a matter of adding 2gms to take the reading upto 6.5

Only if you are measuring your TA expressed as tartaric.

Personally, I've never understood measuring TA as sulphuric. Firstly, because there is no sulphuric acid in grapes (or most any fruit, for that matter), and second, because the idea of doing so is a French concept.

However, if you use tartaric as the standard, it makes acid additions easy to calculate and meaningful. For example, if the TA is at 5.8 g/L and you want to bump it up to 6 g/L, it only takes some basic maths to calculate that's a 0.2 g/L addition.

[goldseal]

Agreed. The Ritchies kits work in sulphuric, so ...

Measure in sulphuric
Convert to tartaric
Calculate the addition

[NorthernWiner]

Pete, just out of curiosity, what is the "normality" of the sodium hydroxide solution that comes with the Ritchies kit?

[Rich]

Steve, Just checked on mine and it doesn't say at all. either on the bottle, or in the instructions (or on the box).

[kampervan]

well i got home to a box of grapes. so i crushed and then split treb grapes into 2 lots one added the scottish grapes at 1050 so giving a final sg of 1080 the other half added apple juice also to 1080. dont know acid as dont have kit but just ordered one after going to local home brew to be told youngs have discontinued item. but did get 3 youngs cherry kits. reds are all going well now.

[goldseal]

Pete, just out of curiosity, what is the "normality" of the sodium hydroxide solution that comes with the Ritchies kit?

I think it's 0.1N. Trying to find confirmation at the moment.

[koomber]

I think it's 0.1N. Trying to find confirmation at the moment.

I'll take some into work tomorrow and have a go at it with an indicator and some acid.

[koomber]

Pete, just out of curiosity, what is the "normality" of the sodium hydroxide solution that comes with the Ritchies kit?

I just worked it out:

From the Richies Test Kit:

5mL of NaOH = 5g/L of H2SO4

This basically means that in a 5mL NaOH sample, we will have enough NaOH to exactly react with 5/gL H2SO4

Therefore
= (5/98.02) moles of H2SO4
=0.051
But, H2SO4 has 2 atoms of acidic hydrogens per molecule, therefore the NaOH will have to be twice as strong.

EQUATION: 2(NaOH) + H2SO4 ---> Na2SO4 + 2(H2O)
Both sides are balanced out. A properly balance chemical equation should account for all components on both sides.

So the Normality should be 0.102 NaOH

Incidentaly, by the time I went through Uni they had scrapped normality in labs, we worked exlusively in molarity and moles. I've had a quick scan at what normality is, and it just appears to be molarity but taking into account the number of reactive sites (hydrogens/hydroxides/etc)

EDIT: If you work this out for an organic molecule, not all hydrogens will be acidic.

[NorthernWiner]

So the Normality should be 0.102 NaOH

Sounds darn close to 0.1 to me.

[koomber]

Sounds darn close to 0.1 to me.

I can almost hear my organic chemistry lecturer's blood boil