what is highly modified base malt
From: Malt Modification
In general, modification refers to the extent to which the endosperm breaks down. During the malting process, enzymes break down the cell structure of the endosperm, releasing nutrients necessary for yeast growth and making the starch available for enzyme degradation during mashing. Modification of the endosperm correlates with growth of the acrospire. As the acrospire grows, chemical changes are triggered that result in the production of numerous enzymes, which are organic catalysts. Their function is to break down the complex starches and proteins of the grain.
The modification starts at one end of the kernel and works its way to the other. It can be stopped at any point by the maltster. One indicator is the Kohlbach Index of soluble to total protein ratio. A highly modified malt will have a KI of 45 or higher.
An under-modified malt has long molecules that can only be broken down by doing a complex step mash with several low-temperature rests. A highly-modified malt can be used with a single temperature infusion mash. A small amount of under modified malt can provide proteins to increase foam and head retention to beers that need it.
Small correction:
The KI is variety-dependent.
A well-modified malt can have a KI of 38 whereas another variety may need a KI of 50.
Comment:
The most commonly used parameter to measure modification for large malsters is beta glucans.
Not correct.
Both undermodified and well modified base malts have all needed enzymes provided a correct kilning process.
Does this show up on the malt analysis sheet?
Modification and diastatic power are not the same. In fact, many under-modified malts are very high in DP. Here is an example data sheet from Mecca Grade under-modified wind malt: https://www.udrop.com/625L/MGEM_Gateway.pdf?download_token=db373952e6c14beb3b9a923d05d9c4e3b73b3197a0a1e4054e0a133585630e4f
S/T = 34-35%
Beta Glucan = 660 mg/l
DP=180-200
Undermodified malts have not had their proteins sufficiently broken down for getting clear beer with good mouthfeel and head with a single infusion mash. You generally need to do a protein rest and the usual saccharification rest when using undermodified malts.
No.
It has some variability, so they prefer to report friability or viscosity.