Barley Starch for Brewers (IV: Granules)


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Starch granules contain alternating layers of less dense, amorphous starch (light blue) interspersed with more tightly packed, semi-crystalline regions of starch (dark blue). When exposed to water, the less dense regions swell, disrupting the internal structure of the granule.

Starch is composed of amylose and amylopectin. In barley malt, however, starch does not exist as a pure mixture of these two molecules, contained by the husk. Instead, Amylose and amylopectin are associated with other molecules, and packed into to tiny granules.

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Barley Starch for Brewers (II: Amylose)

Today is the first day of starch week on Beer and Wine Journal. (It’s like Shark Week on Animal Planet, but instead of ridiculous made-up crap about sharks, it’s facts about starch.) See the introduction to the series for an overview of the topics to be covered. Today’s post deals with amylose, one of the two main components of starch.


Glucose molecules joined in alpha 1 –> 4 linkages. In barley, amylose molecules typically range from 500 to 5,000 glucose residues.

The articles that compose this series on starch will have a few common themes. The most important is that the word starch refers to a variety of things, not a single, defined entity. For example, starch is composed of amylose and amylopectin. Any combination of these two molecules — from 1% amylose to 99% amylose — would be considered a starch, even though differing mixtures would have different properties.

Additionally, in real life situations, starches maybe complexed with proteins and other molecules. These other molecules can change the properties of the starch. Starch is also packed into different sized granules, which affects its solubility. Even heating and cooling starch can change its structure and its properties.

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Barley Starch for Brewers (I: Intro and Overview)

Amylase_reactionMuch of the (fairly) recent scientific work on barley starch should be of interest to advanced homebrewers or homebrewers with an interest in biology. This post is an introduction to a series of articles that will review what modern science has revealed about barley starch. Recently, I posted a series of articles on enzymes for brewers. Although it dealt with all brewing-relevant enzymes, not just starch-degrading enzymes, you can look at these starch articles as covering a lot of the same or similar ground, but from the perspective of the substrate, not the enzymes. (There will also be a few new enzyme-related topics, as well)

In this article, I will give an overview of the subject. In the subsequent articles, I will fill in all the details. In the individual articles, I will try to explain the topics so that you don’t need an extensive background in biology or chemistry to understand them.

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