Flow thermal infrared enthalpimetry: Rapid and inexpensive determination of the alcohol content of distilled beverages

Abstract In this work, a simple and inexpensive flow thermal infrared enthalpimetry (TIE-F) method was developed through a combination of flow injection analysis and thermal infrared enthalpimetry (TIE) to determine the alcohol content of distilled beverages (cachaca, cognac, and vodka). The principle used in this method consisted of monitoring the enthalpy of dissolution of ethanol through a low-cost infrared sensor coupled to a flow system. The results showed an agreement between the proposed method and the conventional method, ranging from 96.5% to 99.0%. The obtained limit of quantification (LOQ, 10σ) of 25.10% (v/v) was enough for distilled beverages, which should present a minimum alcoholic content of 36% according to Brazilian legislation. In addition, the TIE-F instrumentation presented costs that were 100 times lower than the instrumentation that was used in the batch TIE, and the time of analysis was significantly reduced. The amount of residue generated was also reduced, thereby providing significant energy savings and easy adaptation to processes on industrial scales.