Wine: Gas and Liquid Chromatography

From the chemical point of view, wines are aqueous alcoholic solutions containing more than 1000 components that can be present at high concentrations (g L ), but also at trace levels (ng L ). Some of these components determine the organoleptic properties of wines, while others are signi"cant for classifying their origin and/or for checking whether some adulteration has taken place. Concentration levels of these compounds vary according to the variety of vine, the climatic conditions under which the grapes were grown, and the conditions under which vini"cation and ageing processes have been developed. The quality of wines is established by sensory analysis, which is clearly correlated to their chemical a process control valve in the beer feed line, which is fed by a constantly running feed pump. More recent technology has made it possible to control the proof more directly by using the temperature-corrected density function of a mass Sow meter, which can be correlated to the proof of the discharge from the still. The only downside to the use of a mass Sow meter is the process lag time that results from having to measure the proof of the distillate after condensation. Additionally, the control valve can be eliminated from this loop by using a frequency inverter, as described above. Some distillers employ a more sophisticated means of controlling the beer feed to the still by use of a cascaded control loop. Typically, a magnetic Sow meter is used to measure the Sow of beer to the still and control the operation of the control valve. The still top temperature transmitter provides a signal which is used to manipulate the control settings for this Sow control loop. In addition to the above controls, one or more condensers must also be controlled. Generally, a control valve on the inlet cooling water line is used to control this process. The control signal typically comes from a temperature transmitter which can either be located on the discharge water line or the discharge product line. Due to the relatively quick Sow rate of the cooling water with respect to the product Sow rate, process control response is generally much better if the temperature transmitter is located on the cooling water discharge line. Finally, if the product is double-distilled in a true doubler, one additional control loop is required. The steam Sow to the steam coils inside the doubler must be regulated. Almost without exception, this loop consists of a steam control valve and a temperature transmitter on the vapour discharge from the doubler. In a manner similar to the still top control, new technology has made it possible to control the discharge proof more directly using a mass Sowmeter.