richie acid test kit

[bill]

hi, got my acid test kit this morning. now only having half bottle of a wine i made left ( apart ftom my fermenting ones) i decided to have a try with it..

i did as per instructions the only problem is it states to add the solution ( sodium hydroxide) till the specimen turn and stays a light pink in colour. i did this with using 3ml of the solution . this would indicate a 3ppt acid content.

thing is i was able to add an extra 2 ml and the colour stayed the same so im a bit confused as to where to actually stop adding the solution .

cheers billy

[goldseal]

JUST before it turns pink, you'll see it go grey. That's when you stop. Well, that's when I stop

[Cellar_Rat]

Yeah - I all but gave up on this . Good for white very difficult with red. Any suggestions?

[bill]

yes i tried it with a red. it started to lighten slowly till it reached a pink colour but was difficult to know when to stop as the transition was gradual . when i dropped the solution in it the top of the test liquid went dark pink till it was shaken to mix it. the pink indication colour doesnt seem very accurate to me as this will depend on how someone is interperating the colour change and what they think a light pink colour is.

it worked but it was difficult to know when i got to the point i should stop adding the solution..

billy

[bill]

JUST before it turns pink, you'll see it go grey. That's when you stop. Well, that's when I stop

ill have a go that way..

[granda]

try this blog,it will help, as he has done a few experiments with red wine acid testing,plus loads of other stuff,so this should help http://wijnmaker.blogspot.com/2009/1...cidity-04.html

[ms67]

colour changing indicators can be extremely sensitive (like 1 drop will swing it), but like many have already said a strong colour to start with makes things very difficult. Try diluting your wine, 2, 3 or 4 times. you'll have to remember how much of course when you come to doing your calcs. i don't use these things meself, plenty of other stuff for me to get right before reaching this stage, but i do have a background in chemistry so my comments are slightly better than a guess. I would however go with advice given by those who do use these kits, experience is better than theory in such matters.

[NorthernWiner]

Yeah - I all but gave up on this . Good for white very difficult with red. Any suggestions?

Do you have a pH meter by chance? If you grow grapes, I'm guessing that you might.

If so, there's actually a very easy way to test acidity that doesn't rely on inspecting for color change. And you can use everything else that comes with the Ritchie Acid Test kit.

1. Measure out a "small" sample of wine or must. The amount doesn't matter, as long as you keep track of how much it is. I use a 15 ml sample.
2. Measure out a sample of sodium hydroxide (NaOH) solution using a syringe (I also start with 15 ml/cc), and begin adding it to the wine sample, a few drops at a time.
3. After each addition, swirl the sample and check it with the pH meter. While it's nice to have a magnetic stir plate for this, it isn't necessary.
4. When the pH reaches 8.2, STOP (once you get to 7 pH, this will happen very quickly, so you have to pay attention).
5. Carefully note how much NaOH was used.
6. Plug your numbers into the formula below:

[75 x 0.1 x NaOH (ml)] ÷ Sample (ml) = Acidity (gm per litre)

So, for example, if you started with a 15 ml wine sample, and added 11.5 ml of NaOH solution to bring it to 8.2 pH, then the formula would look like this:

[75 x 0.1 x 11.5] ÷ 15 = 5.75 gms per litre acidity

Now you may wonder why the "0.1" is used in this formula. This is the "normality" of the NaOH solution that is provided with the Ritchie acid kit. If you use a different normality solution (for example, 0.2N), then you should also change this parameter accordingly.

I understand this probably sounds confusing, but once you've done it once or twice, you'll find it's really quite easy. Or at least easier than trying to detect a color change in red wine.

[Rich]

Yeah - I all but gave up on this . Good for white very difficult with red. Any suggestions?

The instructions with the Ritchies test kit say to dilute with DISTILLED water. There is no need to take account of this in your calculations, as the total amount of acid you are measuring is still the same. Thinning down the red wine will make it an obvious colour change, as Pete has said it's just before as it starts to change.

Adding more solution won't make any difference, as it has already changed colour..

[ms67]

I understand this probably sounds confusing, but once you've done it once or twice, you'll find it's really quite easy. Or at least easier than trying to detect a color change in red wine.

this is definately a better method for red wines where it's colour makes things so hard. and then once you have the gear you would probably use it all the time. Where it get's more complicated is the odd mix of units used to measure concentrations. Theres molarity, molality and normality (and others) and which you'll see will depend on who is supplying/measuring concentrations; could be chemists, old skool and modern, laypeople with a good understanding of such things, or people who think they are all the same. Standardisation takes a long time and the apple cart gets very upset in transitional periods - which we are still in. However, once you have found the units you are happy with then as Steve says it just comes down to plugging the numbers into a simple formula and it will be worth the initial effort. its shouldn't be hard to find conversion tables or formulas to convert one unit to another. You'll just have to pay attention to the units on the bottled solution.

[Cellar_Rat]

Damn I had given this up as utter madness - now it seems I will have to go and fiddle about with it again.....

My plan was going to be.... dilute with 50% water - to get a batch of about 50 ml - my ph meter is a probe type about the size of a board marker so I need the extra volume and it would make it easier to see any change?

Will the water affect the maths? Given that it is Ph7 and acid free?

[lockwood1956]

You can also drop a tiny bit onto some white card to see any changes, but I always dilute with distilled water till its just a light pink....works for me

[bill]

could i not use my baby and keep dropping samples of must in its mouth till it stops cringing like a bulldog eating a wasp ?? or is that against the law

[bill]

ok just had another go, when i put the wine in its red, when i add the water it obveously goes much lighter. when i start adding the solution i get a redish cloud on the top till i mix it in.. at first this seems to make the sample go even lighter .

i then carried on adding the solution and again get the red cloud on top till mixed. eventually this red cloud starts to turn grey on shaking.

if i carry on adding solution this sample then turns and stays the same red as the cloud i get when first putting it in.. is this the correct way of doing it??

if it is thats cool.

the instructions say to add solution till sample turns light pink but that happens as soon as iv added water and stays pretty much the same till it gets a grey cloud then a few drops later turns to the same shade of pink as you get at the top of the test tube whilst adding the solution before shaking..

billy

[lockwood1956]

if i carry on adding solution this sample then turns and stays the same red as the cloud i get when first putting it in.. is this the correct way of doing it??

Correct!

(I'm fairly sure your baby theory would be frowned upon by the authorities.....might prove more accurate than a test kit though? )

Remember theses test kits are a reasonable guide, and when using them, and adjusting the acid, be sure and taste the must too, so you build up a picture of different acidity profiles on your palate