Malt COA Series #1 – Cytolysis: The Dissolution of Cells

What does this mean for brewers and distillers?

 

By: Living a Stout Life and Malteurop Malting Co

 

A malt certificate of analysis, more commonly known as the COA, is a tool used by brewers to help them understand how a malt will perform in a recipe. The COA lists the results from a grouping of standardized tests that give brewers specific data regarding sampling, moisture, extract, color, physical constants, diastatic power, and more for each malt.

 

So where do the tests and the data originate from? Maltsters, of course. But before then, it all starts with the barley.

 

The COA Begins with Barley

Barley comes straight from nature, and in its true form, it does not provide the enzymes brewers need. That’s where malting comes in. Because of constantly changing agricultural factors such as weather and soil, the malting process has to adapt to these changes to supply quality malts to brewers.

 

The COA continuously defines and analyzes the evolving characteristics behind the malts. This gives the brewers necessary information to adapt as needed to continue producing their best quality products and to further understand the finer nuances of craft beer.

 

A Very Brief History of the COA

Since beer has been around for 4,000 years, the COA is relatively new. It was first introduced less than a year after prohibition ended in 1933. Brewers finally had something tangible to help them adjust to the ever-changing barley that is an imperative ingredient to craft beer and spirits. To learn more about the history, click here for a quick malting fun fact.

 

Science and Art Collaborate to Create Beer

To fully understand how a COA functions and what it means to brewers, we need to first understand the entire malting process from a cellular level.

 

Meaning, get ready for some science speak. After all, brewing beer is all about the science behind the art. Or is it the art behind the science?  That may be a lesson for another day.

 

Today’s lesson, though, is all about the endosperm and cytolysis, better known as the dissolution of cells. Maltsters expertly breach the cell walls to access the starches and proteins that ultimately provide ethanol.

 

Barley’s Endosperm Provides the Perfect Base for Beer

Barley’s Endosperm is a treasure trove of functional components. These components are key to the kernel’s ability to make a new plant. Fortunately, maltsters have learned how to take advantage of this biochemical process in order to provide a perfect base for beer.

 

A bit about the structure of the Barley Endosperm (illustration below). If you have ever tried to chew an unmalted barley kernel, you will know that it is a very dense, strong structure. This strength protects the barley kernel in the field until the warmth and moisture of the next spring comes along.

 

Accessing the Ethanol Without Lautering Problems

If you look at the microscopy picture, you will notice that the Starch and Protein are locked up inside strong cell walls made of Beta-glucan, Pentosan, and Protein. The Protein and Starch inside the cell walls are critical to the kernel’s ability to produce a new plant. So if we want access to the Starch inside the cell so it can achieve its highest potential (Ethanol!) then the first thing we must do is breach those fortified cell walls.  The first enzyme required to break down the walls, Beta-glucan Solubilase, is in the barley when it is harvested. But this enzyme not only makes the Beta-glucan soluble, but very viscous (can you say lautering problems?).

 

Gaining Head Retention and Palate Fullness

Fortunately, there is another hydrolytic enzyme that is formed in response to the saturation (rain or steeping) of a living embryo: Endo-beta-glucanase. This enzyme breaks down the long chains of Glucose molecules that make up Beta-glucan into bite-size pieces that don’t result in stuck lauters. In fact, the bite-size Beta-glucans help with head retention and palate fullness in beer.

 

Endosperm Cell Walls Are an Excellent Source for COA Data

So how does the maltster measure their success in getting the Endosperm cell walls to this good place? There are a couple of tests that give a picture of the degree to which the mission was accomplished.

 

Fine-Coarse Extract Difference (F-C)

Starting from oldest method to newest, we know that the Fine-Coarse Extract Difference (F-C) was the best way early maltsters had to assess the breakdown of the cell walls. When mashed, the availability of Starch to convert to Sugar was determined by the difference in a finely ground sample that thoroughly exposed the Starch versus a very coarse grind which made the uptake of water more difficult.

 

Viscosity

The second test to come along was Viscosity, which measures a liquid’s ability to flow (think water vs. maple syrup). Viscosity is a relatively easy test to perform, with numbers over 1.6 indicating increased likelihood of unsuitable resistance to flow.

 

Beta-glucan

The next two methods came into common use in the 1980’s. The first method measured the problematic long-chain (>10,000 Mol. Wt.) Beta-glucans that adhered to a fluorescent dye called Calcofluor. This was a big deal, allowing high-throughput analysis of malt samples.

 

Friability

The other is Friability, which measures how easily malt is crushed due to the proper breakdown of the Endosperm cell wall. A second number that is obtained from the Friabilimeter is the percentage of Glassy, or Wholly Unmodified Grains (WUG). This measurement tells the maltster and the brewer the percentage of barley that went through the malting process without being modified (physically and biochemically transformed).

 

Breakdowns are Necessary for Good Beer Behaviors

When maltsters and savvy brewers look at a COA, the 4 measures of cell wall breakdown (F-C, Viscosity, Beta-glucan, and Friability/Glassy) are evaluated to see if they all give a consistent picture of cell wall breakdown. If this combination looks good, we can proceed towards measuring how well we broke down the Protein to gain access to the Starch.

 

Click here to learn all about protein breakdowns to promote good beer behaviors, including

healthy yeast behavior, head formation, retention, and body and mouthfeel.