NOVELTY - Monitoring the fermentation process of a liquid, involves: placing the liquid in a container (101) having a headspace; and with a fuel cell sensor (104), measuring a percentage alcohol content of at least one vapor sample taken from the headspace during fermentation of the liquid.    USE - For monitoring the fermentation process of a liquid selected from wort, beer, must and wine (all claimed); and for measuring the percentage Alcohol By Volume (% ABV), specific gravity or sugar content of a fermented liquid.    ADVANTAGE - The automated method calculates changes in the specific gravity of a fermenting liquid based upon changes in measured alcohol concentrations. This method allows for the fermentation progress to be consistently monitored using electronically measured alcohol concentrations rather than using the traditional manual specific gravity measurements. Because a manual sample is no longer needed or required, the progress of the fermentation can be monitored and analyzed automatically in real time, freeing the brewer or technician to perform other tasks (or to allow a less skilled employee to monitor the fermentation). In addition, the efficacy of the measurements is increased since the measurements can be taken at a much higher rate, thus provides better insight into determining the quality of the fermentation and knowledge of when the product is ready for transfer. Finally, as the tests can be performed without opening the fermentation vessel, the likelihood of contamination is decreased.    DETAILED DESCRIPTION - Monitoring the fermentation process of a liquid, involves: placing the liquid in a container (101) having a headspace; and with a fuel cell sensor (104), measuring a percentage alcohol content of at least one vapor sample taken from the headspace during fermentation of the liquid. The method involves placing a fuel cell sensor in an antechamber in vapor communication with container; and with the fuel cell sensor, measuring a percentage alcohol content of a vapor sample taken from the antechamber during fermentation of the liquid. An INDEPENDENT CLAIM is included for a system for monitoring the fermentation process of a liquid, comprising: a fermentation vat filled with a liquid and a headspace above the liquid; a sensor housing (102) integral to the fermentation vat, where the sensor housing defines an antechamber; a sampling mechanism (103); a sampling inlet (205); and a fuel cell sensor; where the concentration of alcohol in the antechamber is generally and proportionally the same as the concentration of alcohol in the liquid; the sampling inlet connects the sampling mechanism to the antechamber; the sampling mechanism connects the sampling inlet to the fuel cell sensor, where the sampling mechanism takes at least one fixed sample from the antechamber on demand through the sample inlet; and the fuel cell sensor determines the percentage of alcohol in each of the fixed sample.    DESCRIPTION OF DRAWING(S) - The figure shows a front cut-through view of the fuel cell fermentation monitor.    Fermentation vat (101)    Fuel cell sensor (104)    Sampling inlet (205)    Temperature sensor (207)    Vent (300)