Winemaking and technical services to the wine industry

Formol Titration method

Supplied by Michael Liedtke of Laffort

Apparatus and reagents

PH-meter
Burette
Aqueous solution of NaOH (N)- mother solution
Aqueous solution of NaOH 0,1 N
Aqueous solution of pure Formaldehyde (35% minimum)- Its pH will be adjusted to 8,5 (every day before use)
Solution of Peroxide (30%), H2O2

Method

1. Take 50 ml of juice (if you already added SO2 in the must put 2 or 3 drops of H2O2 in before starting)
2. Adjust the juice to pH 8,5 with the solution of NaOH (N)
3. Add 20ml of formaldehyde adjusted to pH 8,5
4. Wait a few minutes
5. Titrate to pH 8,5 with a solution of NaOH (0,1 N)

The value titrated will be "n" ml

Total assimilable N=n x 28mg/L

150mg/L of assimilable N is the minimum required to avoid any problem of stuck fermentation due to lack of nitrogen.

A more detailed discussion with some variations can be obtained from the Zoecklein site.

Read all about this.

Feel free to contact Loftie Ellis on any wine related subject by Email at winequality@gmail.com or contact us at

Tel: 021- 883 9017
Fax: 021-882 9487
Cell: 082 825 2489

Wine Quality Consultants
P.O. Box 6231
UNIEDAL
7612
South Africa

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