Editing Pellicle
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[[File:Cider-pellicle | [[File:Cider-pellicle.jpg|frame|right|A pellicle on cider pitched with wild microbes|alt=Pellicle on cider]] | ||
A pellicle is a film (or "velum") that can form on the surface of a fermentation. It is created by some types of yeast and bacteria, when oxygen is present.<ref name="MTF-pellicle">[http://www.milkthefunk.com/wiki/Pellicle Pellicle.] Milk the Funk wiki. Accessed April 2020.</ref> A pellicle may be white, off-white, or clear and it generally has a powdery, waxy, or slimy appearance, often with bubbles or wrinkles (never fuzzy or hairy). It should not be confused with [[mold]], [[kraüsen]], "[[yeast rafts]]", or films from oils. | A pellicle is a film (or "velum") that can form on the surface of a fermentation. It is created by some types of yeast and bacteria, when oxygen is present.<ref name="MTF-pellicle">[http://www.milkthefunk.com/wiki/Pellicle Pellicle.] Milk the Funk wiki. Accessed April 2020.</ref> A pellicle may be white, off-white, or clear and it generally has a powdery, waxy, or slimy appearance, often with bubbles or wrinkles (never fuzzy or hairy). It should not be confused with [[mold]], [[kraüsen]], "[[yeast rafts]]", or films from oils. | ||
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== Myths == | == Myths == | ||
Myth: '''Brewers yeast can form a pellicle.'''<br /> | |||
Truth: With the exception of sherry (flor) yeast, it does not. This myth stems from brewers with recurrent [[contamination]] issues.<ref>[https://www.homebrewtalk.com/forum/threads/thin-white-film-floating-in-secondary.49591/ Thin white film floating in secondary?] HomebrewTalk forum. December 2007.</ref><ref>[https://www.homebrewtalk.com/forum/threads/post-your-infection.71400/page-98#post-8835819 Post your infection.] HomebrewTalk forum. April 2020.</ref> In reality, unless you pitch a yeast known to form a pellicle, any pellicle was definitely created by wild microbes that were somehow introduced into the beer or wine. | |||
We have reached out to some of the major yeast labs to verify whether their strains produce pellicles: | We have reached out to some of the major yeast labs to verify whether their strains produce pellicles: | ||
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On his [https://phdinbeer.com/2015/01/30/beer-microbiology-what-is-a-pellicle/ blog], Dr. Matt Humbard discusses the ability of ''Saccharomyces'' to form a pellicle. | On his [https://phdinbeer.com/2015/01/30/beer-microbiology-what-is-a-pellicle/ blog], Dr. Matt Humbard discusses the ability of ''Saccharomyces'' to form a pellicle. | ||
Myth: '''White Labs WLP644 forms a pellicle.'''<br /> | |||
Truth: White Labs says that [https://www.whitelabs.com/yeast-bank/wlp644-saccharomyces-bruxellensis-trois WLP644 Saccharomyces "Bruxellensis" Trois] can possibly form a pellicle, but doesn't provide specifics about under what circumstances it may occur. However, the consensus among brewers is that it does not form a pellicle, as there have been no recent validated reports of pellicle formation with this strain.<ref>[https://www.facebook.com/groups/MilkTheFunk/permalink/3465266216834901/ Thread about WLP644 Pellicle Formation.] Milk the Funk Facebook group. April 2020.</ref><ref>[https://www.milkthefunk.live/podcast/2019/12/6/wiki-kwiki-005-lance-shaner-of-omega-yeast-labs "Wiki Kwiki #005 - Lance Shaner of Omega Yeast Labs"] (at ~23 minutes) Milk the Funk podcast, December 2019.</ref> Therefore when using a WLP644 culture, it is wise to regard any significant pellicle formation as a likely contamination. | |||
Myth: '''You can rack from under a pellicle to remove the contamination.'''<br /> | |||
Truth: Contaminating microbes are present throughout the liquid. For example, it's common knowledge that microbes like ''[[Brettanomyces]]'', ''[[Lactobacillus]]'', and ''[[Pediococcus]]'' are able to be grown from bottles of commercial mixed-fermentation beers, even though a pellicle was obviously not put into the bottles. | |||
Myth: '''All wild microbes (e.g. contaminants) form a pellicle.'''<br> | |||
Truth: Not all wild mixed yeast/bacteria cultures form pellicles. This is easy to demonstrate by those of us repeatedly (intentionally) capturing wild cultures. The genes that cause pellicle formation aren't always turned on, even if they are present.<ref>Bumgarner SL, Dowell RD, Grisafi P, Gifford DK, Fink GR. [https://www.pnas.org/content/106/43/18321.long Toggle involving cis-interfering noncoding RNAs controls variegated gene expression in yeast.] ''Proceedings of the National Academy of Sciences.'' 2009;106(43):18321–18326.</ref> | |||
== See also == | == See also == | ||
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==References== | ==References== | ||
{{#seo: | {{#seo:|description=Do you have a white film on the surface of your fermentation? Learn about pellicles, what causes them, and how to verify that it is actually a pellicle.}} | ||
|description=Do you have a white film on the surface of your fermentation? Learn about pellicles, what causes them, and how to verify that it is actually a pellicle. | |||
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