Most enological enzymes are specialized enzymes derived from fungi, including Aspergillus niger and Trichoderma harzianum. Enzymes are present in all plants, animals, and microbes, including grapes, yeast, and bacteria, and are responsible for accelerating a variety of reactions. While enzymes are naturally present in grapes, juice, and wine, their activity is limited by fermentation and wine conditions. Enological enzymes can be added to compensate for this lack of activity.

The organism used to produce them, the substrates during production, and the specific formulation all influence what a certain enological enzyme can do in wine.

In winemaking, the main function of enological enzymes is to break down pectin and structural polysaccharides, and release sugar-bound aromas.

Break down pectin and structural polysaccharides

Enzymes can break down complex polysaccharides from the grape (skins and pulp), yeast, and other microorganisms. Breaking down these compounds:

• Releases desirable components such as juice, aroma precursors, color compounds, and texture compounds (tannins and polysaccharides).

• Prevents processing issues such as slow filtrations and difficulties with clarification.

Release sugar-bound aromas

Many varietal aromas from grapes are released into juice/must bound to sugars (both fermentable and non-fermentable) and in this form the aroma compounds are odorless. Specific enzymes can cleave aroma compounds from sugars, converting them to an odor-active form and increasing varietal aroma.

Pectins can be extremely complex and difficult to break down due to a phenomenon known as “branching”. All pectins have a main polysaccharide chain composed of homogalacturonan sub-units. These main chains can also have varying degrees of side-branching* of additional polysaccharides called rhamnogalacturonans, arabinans, and arabinogalactans (see figure above). Enzymes that break down pectin can specialize in breaking down the main chain or they may be able to break down the main chain and some of the pectin side chains.

Enzyme activity is a term that can be used to describe what an enzyme targets, which determines the enzyme’s application. There are a few major categories of enological enzyme activity (see table below).

Enological enzymes are blends of different activities discussed in the table above**. Enzymes are formulated with precise blends of activities to achieve a specific goal.

Even if two enzymes contain a similar blend of activities, the concentrations and ratios of activities can differ which may change the application. For example, enzymes that are used to increase extraction of skin-trapped compounds (aromas in whites, color and tannin in reds) have similar blends of activities – primarily cellulose and hemicellulose activity. However, the enzymes formulated for extracting color and tannin from red grapes have higher concentrations of both activities than enzymes formulated for extracting aroma precursors from white grapes. The enzymes formulated for white grapes are less concentrated to minimize the extraction of undesirable phenolics. This emphasizes the importance of the ratio between activities in a given enzyme formulation.

Enzymes are much like active dry yeast – with yeast, we have come to accept and appreciate that small genetic differences between strains can make a big impact. It’s the same with enzymes - small differences in the composition, concentration, and ratios of activities can change the usage and impact entirely. Throughout this section, check the “frequently used in” boxes for the most appropriate applications of each enzyme.

**All enological enzymes are pectinase-based and contain some amount of pectinase activity.