Wine Making

Contents

Specific Gravity and Wine The basis of wine making is the conversion of sugar to alcohol through the fermentation process. The alcohol yield is directly related to the level of sugar in the must (the stuff being turned into wine, typically a mix of grape juice concentrate and water or parsnips, sugar and water if you are into that sort of thing) at the start and end of fermentation. Most older books express sugar content in ounces per gallon. Some hydrometers are calibrated in ounces per gallon, if not the table below will give you an approximate value of sugar content from the specific gravity.

S.G.	oz/gal	kg/l	% Wt
1.00	0.0	0.000	0.0
1.01	4.3	0.270	2.7
1.02	8.6	0.054	5.3
1.03	12.9	0.080	7.8
1.04	17.2	0.107	10.3
1.05	21.5	0.134	12.8
1.06	25.8	0.161	15.2
1.07	30.1	0.188	17.5
1.08	34.4	0.214	19.9
1.09	38.7	0.241	22.1
1.10	43.0	0.268	24.4
1.11	47.3	0.295	26.6
1.12	51.6	0.322	28.7

A rough guide to the alcohol content of wine is to divide the %wt of sugar at the start of fermentation by two, assuming that the S.G. at the end of fermentation is around 1.00. Typically wine should have an alcohol content between 9 and 11%.