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New World Wine Maker Blog - enzymes

Winemaking in the Rhineland-Pfalz: Part 2

During my recent harvest stint in Germany, my host, Christoph Hammel uttered many memorable (and some that I am not allowed to mention here) pearls of wisdom. He told me about a meeting where some of the biggest names in German winemaking and professors associated with the wine industry were present. A very well know professor publically stated that his belief system does not have any room for the theory that yeasts impart any aroma to a wine fermentation. At this, Christoph got up and glibly replied: “My dear sir, it is not a question of belief. It is a question of knowledge.” The subsequent pandemonium that ensued was apparently quite noteworthy (hence the photo above).

Christoph is a big believer in using technology, specifically technology that can be used to make wine, and wine processing, better. Even more specifically, he is a big believer in additions.  He always said to me that he makes wine that people want to drink and if this can be achieved with the addition of enzymes and other winemaking tools, so be it. Every addition that he does is done for a reason. One thing can be said with certainty and that is that Christoph believes in the “interventionist” approach to winemaking. A lot of winemakers like to claim that their wine is made “naturally” and with the least possible human intervention, but Christoph is at the complete opposite of the spectrum. He has some pretty far out and amazing ideas and some might even call him a renegade or a cowboy after hearing about his yeast mixing and addition regimes!

As far as the additions are concerned, Optiwhite (Lallemand) is one of his stalwarts. This is usually added at the beginning of fermentation. β-glucanase and β-glycosidase enzymes  are added at the end of fermentation (at about 0°Brix). Depending on the structure and quality of a specific wine, ascorbic acid is also added right at the end of fermentation. DAP is added at three stages and is sometimes even added in divided dosages during the day, depending on the fermentation bouquet. In addition to DAP addition, thiamine is added to all musts. This is done simultaneously with sugar addition. It is well known that fungal infection on grapes depletes thiamine and it is therefore an excellent prophylactic measurement against stuck, sluggish or smelly ferments. For each addition, a cost to benefit decision is made. For instance, light and easy drinking wines will not get all the bells and whistles. The more expensive wines will get a full range of stuff added.

If Christoph was not such an excellent winemaker, I would have said that he missed his true calling in life: A chef! A chef who is forever mixing, adding and tasting, mixing, adding and tasting…

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Think pink!

Now I bet very few of you have given this any thought. After all a rosé and a blanc de noir is a “white wine” made from red grapes. So you use your normal settling enzyme. However, this “white wine” contains a certain amount of anthocyanin, which means this anthocyanin should preferably remain a stable colour to ensure the longevity of the wine. In plain English, the wine should preferably remain pink or onion skin, whatever our style is, for a year or longer. It should not turn slightly brownish. In the absence of tannin from the grapes, or ellagic tannin from wood, or oxygen from micro-oxygenation, how does one stabilise this colour? Well for one; keep stuff that can de-stabilise it in the first place away from it. 

 Anthocyanin, like I said in a previous blog, is stabilised by sugar molecules. When the sugar molecules are removed the colour becomes unstable and can lose it red tinge and become, well, less red. I am not a specialist on polyphenols and bless the souls of the people who are because I find the topic extremely complicated. I have tried and tried to fully comprehend the colour / tannin chemistry in wine and I am not sure if it is lack of intelligence or sheer boredom with the topic that makes it impossible for me to fully grasp it.  Anyway having gotten that of my chest, lets stick to the very simple model of anthocyanin and its sugar molecules.

 Settling enzymes (white wine enzymes) can contain a side activity, formed by the fungus during production, called glycosidase. This activity is also known as “anthocyanase.” It removes sugar molecules from more complex structures. Although very positive for white wine aroma, it can also potentially remove the sugar molecules from anthocyanin. Now granted, you need a certain concentration to have an effect and some settling enzymes may not contain high enough amounts to cause any damage to your colour. It is nonetheless a good idea to clear this matter with your enzyme supplier to make sure that there will be no effect on your rosé colour.  There are quality and composition differences between suppliers and it is a good idea to be aware of these differences. To make absolutely sure that you don’t have this activity in the enzyme you use for settling, use a red wine skin contact enzyme, where the supplier specifies: anthocyanase free, for settling of your rosé or blanc de noir juice. Skin contact enzymes contain the basic ingredients of settling enzymes as well as added side activities needed for skin pectin breakdown. So, it is a very effective settling enzyme as well, more expensive, due to the added activities, but very effective.

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Is it okay to use my normal settling enzyme for red wine maceration?

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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