The Measurement of Density During Wine Fermentations Using Pressure Transducers

The changes in density and weight loss of juice during a 1500 L wine fermentation were measured using several pressure transducers. The influence of the sensor precision, the vertical separation of the transducers and the ambient temperature and pressure variation on the measurements were investigated and compared with density of samples using a hand-held densitometer. The effect of data smoothing across short and long time-domains was investigated. The transducer measurements were in agreement with the manual measurements. The precision of the Brix measurement was determined for the different spacings. The density and weight loss data were then contrasted using a parameter estimation routine and an existing fermentation model with both measurement approaches. The maximum fermentation rate determined from the first derivative of these measurements was compared to that estimated by the fermentation model.