- by titration to end point by colour indicator
- by titration to end point using pH meter
- References and further reading
This document gives a brief summary of the procedures and equipment requirements for some commonly used techniques for determination of TA of grapes and wines. The TA is usually determined by titration with a sodium hydroxide solution of known concentration to a specific pH end point indicated either by a colour change of an indicator dye, or by a pH meter. In the case of the latter, automated titration systems are available and can offer considerable benefits to laboratories that routinely analyse relatively large numbers of samples.
Titration to end point by colour indicator
Description: The TA of grape juice or wine is determined by titration to an end point of pH 8.2 as indicated by a colour change (clear to pink) using phenolphthalein indicator solution. Wine samples are degassed prior to measurement to remove dissolved carbon dioxide.
Equipment: Burette for titration, flasks and vacuum for degassing (or nitrogen gas for sparging)
Reagents: Sodium hydroxide solution, phenolphthalein indicator solution
Calibration: Use standard buffer solutions, recommended daily or as per manufacturers instructions
Services: Wash up area
Space required: Small bench area
Titration to end point using pH meter
Description: The TA of grape juice or wine is determined by titration to an end point of pH 8.2 as indicated by a pH meter. Wine samples are degassed prior to measurement to remove dissolved carbon dioxide. The measurement is subject to temperature effects, due to both sample and instrument, and must be corrected, with most meters and electrodes having automatic temperature compensation.
Equipment: Burette for titration, pH meter, pH electrode, flasks and vacuum for degassing (or nitrogen gas for sparging)
Reagents: Sodium hydroxide solution
Calibration: Use standard buffer solutions, recommended daily or as per manufacturers instructions
Services: Electricity, wash up area
Space required: Small bench area
References and further reading
- Amerine, M.A.; Ough, C.S. (1980) Methods for analysis of musts and wines. New York Wiley-Interscience.
- Iland, P.; Ewart, A.; Sitters, J.; Markides, A.; Bruer, N. (2000) Techniques for chemical analysis and quality monitoring during winemaking. Campbelltown, SA Patrick Iland Wine Promotions.