why are the brix readings of fermented solutions usually higher than unfermented beverages
Brix Alcohol has a higher refractive index (1.361) than water (1.333). As a consequence, a refractometer measurement made on a sugar solution once fermentation has begun will result in a reading substantially higher than the actual solids content. Thus, an operator must be certain that the sample he is testing has not begun to ferment. Brix or Plato measurements based on specific gravity are also affected by fermentation, but in the opposite direction; as ethanol is less dense than water, an ethanol/sugar/water solution gives a Brix or Plato reading which is artificially low.
Long Island Iced Tea The drink has a much higher alcohol concentration (approximately 22 percent) than most highball drinks due to the relatively small amount of mixer. Long islands can be ordered "extra long", which further increases the alcohol to mixer ratio.