Further Studies with Controlled Fermentations

¹ University of California, Davis, California

The art of winemaking, like that of brewing, is undergoing a rapid metamorphisis in the 20th century. As more and more of the technical details influencing quality are brought under the control of the wine maker the art of winemaking will gradually become the science of winemaking.

A variety of reasons may be given for this transformation. The scientific skills necessary for converting the industry have only been developed within the past 100 years and are by no means fully understood today. Even where the process variables were recognized the necessary instrumentation for their automatic measurement and control were not available. However, the great progress in the antibiotic industry has shown how far the fermentation industries can be brought under strict control. A second reason is our desire, and need, for uniformity. The intuitive type of control produced some very fine products but also some very poor ones. Efficiency is another reason for these developments. The cost of the raw material and the labor overhead have gradually become so great that we must control their efficient utilization. Competition alone requires efficient controlled operation.

This point of view was sumarized by Silox and Lee (1948) as follows:

"Although fermentation is one of the oldest processes and has important economic significance due to its widespread use in industry, it must still be classified as an art rather than a science. This is in part due to the complex nature of fermentation and the large number of independent and dependent variables that affect the evaluation of results. Secondly, although fermentation involves difficult interrelated problems in biology and engineering, men in these two fields have worked independently until recent years."

Of the three primary factors influencing the final quality of a wine we normally consider variety, fermentation procedure and aging in a decreasing order of importance. Actually, no fine wine can result when any of these three are neglected, so that in studying controlled fermentations there is no intention of minimizing the importance of the other two. Furthermore, there is an interrelation between the three which complicates their separate study. For example, a white grape requires a different fermentation procedure and method of aging than a red. A high acid must will ferment better and with less care than a low acid must and the wine will be more stable—other factors being equal.