Experimental Fermentation with and without Pectic Enzymes

Abstract

Let us assume for the moment that no undesirable characteristics in wines develop from the use pf pectic enzymes. These experiments did not show any reason why pectic enzymes should not be used and, further, they did suggest some interesting possibilities.

For example: if the fermentation time can be shortened through the use of pectic enzymes, more grapes may be used at optimum maturity. At optimum maturity a higher percentage of the Brix is fermentable sugar, and this should be good for some increase in yield. And further, at optimum maturity flavor and color should be at their peak.

If pectic enzyme treated fermentations contain less residual reducing sugar, some increase in yield and less loss of sugar in pomace are possible consequences. At the same time, the use of pectic enzymes could make pomace easier to drain and press, and alcohol losses in pomace could be reduced thereby. One per cent of alcohol in pomace runs to lots of proof gallons of alcohol during a while crushing season. Hence, the less pomace from the press, the smaller the loss.

If pectic enzymes facilitate and speed up low temperature fermentations in full scale operation as they did in several of these experiments, a substantial saving of time is possible. If low temperature fermentations can be conducted without the addition of sulfur dioxide and can still produce wines of low volatile acidity, low temperature fermentation should be adopted more widely. Besides, there is presumably less alcohol evaporation loss from a low temperature fermentation than from one of high temperature -- another potential saving.

If the use of pectic enzymes in actual operation results in a more quiet fermentation -- that is, with less foam -- there should be less alcohol lost on account of bubble entrainment.

If the unpleasant sulfurous odors during fermentation are due to some action of the pectic enzyme on the sulfur dioxide added to fermenting juice, the desirability of learning how to make wine without sulfur dioxide would seem to be indicated.

The formation of volatile acid seemed to be connected with the length of time the fermentation took to approach dryness. Just why the fermentations containing Pectinol should be so much lower in volatile acid is not clear.

The last experiment, using a 35 Brix juice, suggests the possibility of making 16 per cent alcohol high-Balling wines by natural fermentation. Offhand it seems that they should be better flavored wines.

Some of these experiments ought to be repeated using freshly crushed grapes or fresh juice in place of grape concentrate. It is quite possible that there might then be some variation from the results reported here. Commercial size experiments might reveal still further variation in results because of mass action of large quantities.