Biological De-acidification Methods
ProMalic - A New Tool for De-acidification
Note: - costly with potential for problem if not handled correctly.
Schizosaccharomyces pombe, sold as ProMalic is a biological de-acidification tool for wine makers having to deal with high acidity, together with a high ratio of malic to tartaric acid. This especially true of most cold hardy types. ProMalic metabolizes malic acid into ethanol instead of lactic acid (as with malolactic fermentation). Notes: a wine with a high acidity requires body and residual sugar for balance (Rankine, 2004). High acidity inhibits malolactic fermentation.
Scott Labs and it's dealers has ProMalic available. Instructions for use are here:
The following is taken from: http://www.lallemandwine.us/products/others.php
ProMalic® For naturally lowering juice acidity.
Schizosaccharomyces pombe is a yeast that metabolizes malic acid into alcohol. In theory, this yeast would be a good alternative to malolactic fermentation or chemical deacidification, however, it is usually considered a spoilage organism due to its production of off-characters when left too long in the wine after fermentation. Proenol has successfully encapsulated Schizosaccharomyces pombe in double-layered alginate beads. Alginate is an extract of seaweed. The product, ProMalic®, is added to the juice at the beginning of the alcoholic fermentation and removed once the desired malic level is achieved. The safe use of ProMalic® Schizosaccharomyces pombe opens the door for winemakers who want an alternative to acid reduction without the production of lactic acid or chemical deacidification.
Here is a comment on ProMalic from http://www.winepress.us/forums/index.php?/topic/14492-harvest-in-pictures/page-2?
The ProMalic was add to my batch of Sabrevois. The pH was 2,83 and the TA 12,5gr/L. After 5 days of maceration with the ProMalic I am at 3,30pH and 10gr/L. The pH effect was nice but the TA is not so impressive. I would have like to see something like 8-9gr/L. I am happy with the end result and I will use more next year. This is a bit more time consuming then normal yeast but it is simple. You need to add some sugar to warm water and condition the yeast for few hours before you are ready to pitch them. You need to use some kind of a ballast or any weight that you fit into the barrel or tank bag with the encapsulated yeast. The yeast are not very tolerant to the alc. %. There toxicity point is about 7-8% so that's why I did remove them after 5 days. If you let them past this point you can get some sulphide compound but if done properly you are quite ok with the flavors. I saw no bad flavors or taste. What I think I will do next year is to ferment a little bit cooler to prolonge the maceration time and get more conversion. This yeast convert the malic to ethanol but I don't think it has the time to convert all of my malic acid so I am still adding MLB to be sure I convert it all. My goal with this was to reduce my acidity by avoiding the formation of lactic acid. I will soon ask Lallemand as I have few more questions relating to the alcohol production and malic convertion speed. You might to try the ML01 OGM yeast as it is faster and it produce lactic acid but no alcohol.
Maurivin B yeast gives very good results for high acid wines; it consumes up to 56% of malic acid.
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