FLOW-INJECTION PIEZOELECTRIC DETERMINATION OF BRIX IN SUGAR-CANE JUICE AND IN THE ALCOHOLIC FERMENTATION PROCESS

A flow injection piezoelectric procedure is proposed for the determina tion of brix (total solids dissolved) in the alcoholic fermentation pr ocess. A piezoelectric Perspex cell was constructed to fit one of the gold electrodes of a 10 MHz crystal and this sensor was adapted to a f low injection system. The analytical curve is linear over the brix ran ge from 0.5 to 20.0% with a detection limit of 0.3%. Seventy results c an be obtained per hour and the relative standard deviation was less t han 1.45% for a solution containing 6% of brix (n = 15). Applications of this method for the determination of brix in sugar cane juice and i n an alcoholic fermentation bench show satisfactory results in compari son with refractometric and densimetric methods, respectively.