pH reading.

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pH reading.

Postby Johntheeng » Wed Nov 23, 2016 16:59

I have decided to start taking pH readings when making my wine instead of blindly following recipes. Hopefully I will get a more consistent tasting wine. Can any one tell how they take their readings and what benefits to be gained and if it does improve the end result.
Thanks.
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Re: pH reading.

Postby Bad 'Ed » Wed Nov 23, 2016 21:13

Most people who take the pH prefer an electronic meter to the strips. I don't think the strips are always that consistent.

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Re: pH reading.

Postby john luc » Thu Nov 24, 2016 12:47

Strips are ok but its hard to confirm exactly what PH you are reading from. If you are going to buy a meter don't waste your money on a cheap one as they feck up too easily.
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Re: pH reading.

Postby Aleman » Thu Nov 24, 2016 14:49

pH is not of that much use in wine making. What is more important is the 'Titrateable Acidty' which is usually quoted as ppt sulphuric (Parts Per Thousand).

Why?

pH is a logarithmic scale and as such is not linear. take as an example a theoretical apple juice that we measure the pH as 4.5. if we then dilute it with an equal volume of distilled water (pH7) the pH will not reduce (actually increase) by 50% to 5.7, it will be something more like 4.8/9. Now if we titrate the acidity with a testing kit and we find it has an acidity of 3.0 diluting it with an equal volume of distilled water WILL reduce the acidity to 1.5ppt sulphuric.

Titrateable acidity is a predictable method of measuring and using acidity in wine making. Ritchie products sell a kit for the purposes of measuring it.

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Re: pH reading.

Postby tonyhibbett » Fri Nov 25, 2016 13:09

I've been using a cheap (£7) meter for years and find it reliable and useful. However it does need to be recalibrated from time to time to maintain accuracy. I also use the titration kit which includes a solution of sodium hydroxide which soon runs out if you use it a lot. However this is in fact dilute caustic soda which readily available from my local grocery store very cheaply. The results are given as parts per thousand sulphuric acid. As a rule, wine acidity is measured as tartaric acid. The conversion is simple - add 50% to the result, so 5 ppt becomes 7.5. As far as I know, tartaric acid is only found in grapes. Other fruit contains malic acid (apples), citric acid (oranges) or combinations of both. All 3 acids have similar strength but differing affects on taste and are reduced at various stages of wine making. The most stable is tartaric but is slightly reduced when the wine is chilled, resulting in the formation of tartrate crystals. Malic acid is stable, unless a malolactic fermentation takes place, which can occur if non sterile fruit is used. Most, if not all citric acid tends to be consumed during fermentation. Also many harmful bacteria are encouraged by it.
Good recipes take account of the best balance of acids, but may not suit all tastes. It makes good sense to take readings before and after fermentation. However if pulp fermenting fresh fruit, more acid is released during the extraction process, and yeast nutrients can lead to inaccurate readings, due to their buffering effect. Therefore measurement is only really valid once the wine is finished. A young wine may have the 'correct' acidity but taste harsh, which usually is corrected by maturation.
A must which is too acidic can be corrected with dilution with water, adding precipitated chalk or potassium carbonate or even plain old bicarbonate of soda. Any deficiency is best corrected with tartaric acid.
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Re: pH reading.

Postby Johntheeng » Fri Nov 25, 2016 20:19

Thanks for your replies everybody. I have found them very interesting and they have given me plenty to think about.
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