There have been some discussions on the forum lately about Fully Modified Malts and Less Modified Malts. For those not familiar, here is an explaination in my own words and link to how to read a Malt Analysis Sheet.
In the process of malting, barley is soaked in water for up to 72 hours with the water being changed every 24 hours. After the soak, the barley is allowed to germinate. The germinating process could take from 8 to as many as 24 days. During the germinating process the barley is turned every 24 hours and kept moist but not wet.
During the germination process, the barley is examined to see when germination is complete. Germination is complete when the new growth stems out from the end of the kernels and up the back of the grain. This growth is called the "acrospire". When the acrospire is roughly the same length as the kernel, the malt is fully modified. If you let it grow longer than the kernel size, the malt is said to be "over modified". If it is shorter than the kernel size, the malt is "under modified".
When the barley is fully modified, the malt is then kilned and cured for 2 to 3 days until the moisture content is 4% to 5%.
The "modification" is important to us brewers. Modification is the term that describes the degree of breakdown during malting of the protein-starch matrix (endosperm) that comprises the bulk of the seed. Undermodified malt still has starch in the grain that could be converted to sugar. Overmodified malt has already started consuming the sugars during the normal plant growth cycle. Fully modified malt is what we seek as home brewers seek because it simplifies our brewing process.
Most malts available to the home brewer here in the US today are fully modified, but there are some exceptions. There are some less modified malts available here in the US from German maltsters.
If a less modified malt is encountered a protein rest during mashing can be used to break down any remnant large proteins into smaller proteins and amino acids as well as to further release the starches from the endosperm. Fully modified malts have already made use of these enzymes so the benefits of a protein rest are not pronounced. In fact, when a fully modified malt is mashed using a protein rest, the body of a beer could be affected, leaving it thin and watery. For fully modified malts, a simple infusion mash can produce stellar results.
As home brewers, how do we know if the malts are fully modified or less modified? The answer lies in the "Malt Analysis Sheet". These sheets give a full description of the malt. A copy of the malt analysis sheet should be available for the asking from your malt dealer. I won't go into detail in this post on how to read a malt analysis sheet. I will defer to an article I found on the internet on how to read a malt analysis sheet. It is an excellent article and it helps you understand the malt you are about to brew with. Here is the URL: How to Become Fluent in Malt Analysis Sheet Interpretation.
I hope this allievates some of the mystery about malt modification. I welcome your comments.