Pellicle

Pellicle from The Yeast Bay Brussels Brett Blend; courtesy of Dan Pixley

Lactobacillus pellicle; courtesy of Matt Humbard

A pellicle is a subtype of biofilm that is formed on the surface of a beer. A biofilm is a community of microorganisms that are connected to one another through the use of material that is present in the environment, such as proteins, long chains of sugars, or live (or dead) cells. It is often formed by Brettanomyces, Pediococcus, or Lactobacillus. It can also be formed by Saccharomyces in rare occasions .

Introduction

Pellicles form when the surface of the beer is exposed to oxygen One theory is that the formation of a pellicle allows the organism to access the small amount of oxygen that is present in the headspace of the fermentation vessel. Another theory, and one that may be less accurate according to Dr. Matt Humbard, is that the pellicle protects the beer from other microorganisms . Popular thought is that the formation of a pellicle is not indicative of the quality of the sour beer that is being produced; it is only an indication that oxygen has entered the fermentation vessel and that the microbes are reacting to that exposure.

Images

• See Google search images.

External Resources

• Beer Microbiology – What is a pellicle? A PhD in Beer blog. Dr. Matt Humbard. 01/30/2015.