Friability refers to a material’s ability to be easily crumbled. In brewing, friability is a measure of the hardness of grains of malted barley. It is, in effect, the grain’s resistance to being broken. A friable grain is one that crushes crisply and cleanly into several separate parts. Friability may be easily assessed by chewing a sample, but this requires experience; it is measured objectively with a friability meter.

Friable grains are desirable in brewing because they indicate that the malt is dry and has been well stored. As a result, its enzymes are likely to be active when hydrated in the mash. In addition, proper drying and storage limits growth of mold or other spoilage organisms that could result in problems in brewing. This said, it is important not to over-dry malt; malt with too low a moisture content may shatter during handling and may be powdered by milling, leading to difficulties in the brewhouse and subsequent quality problems in beer.

Friable grains will also crush into suitable sized pieces to provide proper filtration in the mash bed. Softer grains may be termed “slack” and are more likely to be flattened than cracked in milling. See slack malt. Such grains offer less exposure to the mash liquor and take longer for their starch to dissolve and digest. Poorly dried grains or ones that absorb moisture during storage are more likely to be slack. Grains that are improperly modified, and are therefore still hard, are referred to as “glassy” or “steely”.

A friability meter tests grains by pressing them at constant pressure against wire meshes and measuring the amount passing through.