Taking Density With Hydrometers
Density is measured in sake via hydrometers to determine fermentation progress and sweetness/dryness. Baume and SMV are the density scales typically used in sake brewing. Baume/SMV has an equivalent to Specific Gravity, Plato, and Brix but other scales can be more difficult to read with precision.
There are two types of Baume scales, a heavy scale for liquids denser than water and a light scale for liquids less dense then water. The Baume Light scale is not typically referenced in sake brewing, instead a specialized hydrometer called the Sake Meter Value (SMV) is used to read density when sake transitions from more to less dense than water.
Specific Gravity | 1.0149 | 1.0079 | 1.00087 | 1.0000 | 0.9940 | 0.9872 |
Baume Heavy | 2 | 1 | 0 | – | – | – |
Baume Light | 8 | 9 | 10 | * | 11 | 12 |
Sake Meter Value | -20 | -10 | 0 | 1.26 | 10 | 20 |
Text book of Sake Brewing P118: Table 5-4 Relationship between Specific Gravity, Sake Meter Value, and Baume Degree
The range of Baume heavy hydrometers is between 20 and 0. An SMV hydrometer is equivalent to Baume between 3 to 0 but also goes lower. These numbers are equivalent to -30 and 0 respectively and then lower down to +20. For example if you have a baume heavy reading of 1.2 you will have an equivalent SMV reading of -12.
Needs:
- ~50ml sample of clear sake
- Graduated Cylinder
- Baume Hydrometer
- SMV Hydrometer
Method:
- Place sample in graduated cylinder
- Place appropriate hydrometer into sample
- Read and record your result