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.
Cider English cider contained a drier, higher alcohol content version, using open fermentation vats and bittersweet crab apples. The French developed a sweet, low alcohol "cidre" taking advantage of the sweeter apples and the keeving process.[20] These are the roots of the standard styles we know today. Cider styles evolved based on the methods used, the apples available and local tastes. Production techniques developed, as with most technology, by trial and error. In fact, the variables were nearly too widespread to track, including: spontaneous fermentation, the type of vessels used, environmental conditions, and the apple varieties. Refinements came much later when cider became a commercial product and the process was better understood. However, since there is growing popularity in ciders, the production of specialty styles has begun to increase.[17]