In Processing, Wine Chemistry
This is a question I got from a winemaker a few days ago. Some people selling enzymes will say yes, that any pectinase preparation you use will be better than using nothing at all. I suppose that can be the case. However, here are a few facts to consider when choosing an enzyme for red colour/tannin extraction.
Colour and tannin are mostly situated in red grape skins. The pectin structure of grape skins is much more complicated than the simple structure of the pulp. When your aim is settling only, you work with the pulp of the grape. A simple pectin structure only requires the basic pectinase activities of pectin lyase, pectin methyl esterase and polygalacturonase. That is why settling enzymes are the most cost effective to produce and usually the cheapest of an enzyme supplier’s range of enzymes.
If skin contact is your aim, you need additional enzymatic activities to break down the highly branched, complex pectin structure of skins. So in addition to the basic pectinases, skin contact enzymes contain various “side” activities. The production organism – Aspergillus niger – produces much less of these side activities than the basic pectinases. That is why production of skin contact enzymes is more expensive and you, the end user, has to fork out more. It is a specialised enzyme for a specialised application. So basically skin contact enzymes contain all the components of a settling enzyme, usually in higher concentrations, as well as specific side activities that will work on the more complex pectin structure of skins.
So, common sense will tell you that an enzyme specifically recommended for skin contact will therefore be way more efficient in extracting colour and tannin than a normal settling enzyme. But wait…there is more….if you order now, you get this beautiful set of steak knives absolutely free!!! OK I digress; seriously there is one more factor to keep in mind.
Aspergillus niger also produces a group of enzymes called glycosidases during the commercial production of pectinases. It actually falls under the group of side activities formed. It does it automatically, with some strains producing more than other. Glycosidases remove sugar molecules from more complex structures. In grapes, certain potentially flavour active compounds are bound to sugar molecules. In this bound form they are not flavour active. When the sugars are removed, you can smell and taste these compounds. An example is monoterpenes found in most white grape varieties, especially Riesling and Muscats. They are also found in red grapes. However, red wine colour, anthocyanin, is stabilised by sugar molecules. So by removing the sugars from anthocyanins, glycosidases can destabilise them, making your red wine colour, unstable. So what is a positive in white is a negative in red. Red wine enzymes should preferably not contain any glycosidases, or, as they are more commonly known in this case – anthocyanases.
My advice to you would thus be: make sure that the enzyme preparation you plan to use for red must maceration contain negligible levels of anthocyanase. If your supplier cannot give you that assurance, then switch to a supplier that can give you that assurance. No point in being penny wise and pound foolish. There are ways enzyme companies can manipulate production of red skin contact enzymes to minimise this activity. They generally, however, do not try to limit this activity in white enzymes, such as settling enzymes, since it is a positive for white wine aroma.
Having given you the scientific facts, my personal answer to the above question would be: no, it is not OK to use your settling enzyme for red skin contact. However, if your supplier can guarantee you that the anthocyanase activity in their settling enzyme is negligible, then I suppose some pectinase activity is better than none.
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