This document gives a brief summary of the procedures and equipment requirements for some commonly used techniques for determination of the density (specific gravity, sg) of wine. The two most frequently used techniques are hydrometry and densitometry.
Distillation/hydrometry
Description: This technique measures the density of the liquid. A glass hydrometer with a suitable scale is floated in a sample of the test liquid usually held in a measuring cylinder. Hydrometers can be bought pre-calibrated to a variety of scale ranges of specific gravity. The measurement is subject to temperature effects and therefore the temperature must be measured and the observed reading corrected using published tables. Such correction tables together with simple conversion tables for converting readings in one scale to another have been published (e.g. Amerine and Ough 1980; Rankine 1998).
Equipment: Hydrometer, measuring cylinder, thermometer
Calibration: Pre-calibrated, check with pure water
Services: Wash up area
Space required: Minimal bench space
Distillation/densitometry
Description: Density meters or pycnometers can measure the density of a test liquid with great precision, although the temperature of the sample must be well controlled. In the case of density meters, a variety of scales are available and most instruments have automatic temperature compensation provided.
Equipment: Density meter
Calibration: Pre-calibrated, check with pure water
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.
- Rankine, B.C. (1998) Making good wine: a manual of winemaking practice for Australia and New Zealand. South Melbourne, Sun Books (Macmillan Australia).