Lesson 2 - Barley

The husk of the barley kernel is the dry outer layer (or shell) that covers the kernel.

The husk forms the outermost layer. It covers the grain completely and is made up of two halves: the palea and lemma. The outer husk cells are cuticularised (covered in cuticle). The husk not only protects the grain during handling, but it also prevents excessive water uptake during the malting process. For this reason, if malting grains without a husk (for example wheat or huskless barley varieties) it is more difficult for the maltster to control water uptake than it is when malting normal barley.

The husk’s silica content makes it abrasive, causing wear on grain handling equipment. In maltings we often see pipe bends worn away, especially if the malt is transferred pneumatically. The stainless steel used in germination vessels has a polished surface due to the barley’s abrasive action. Because it is mechanically tough, it also protects the grain from physical harm and helps slow insect damage. The husk also provides a natural defence against mould growth during both barley and malt storage. In the brewhouse, husk forms the filter bed in the wort separation vessel.

Husk composition:

• Lignin
• Silica
• Cellulose
• Pentosans: arabinoxylans ~ 5% of grain pentosans
• Polysaccharide β-glucan
• Phenolic material

Key points:

• Husk contains pigmentation.
• It is rough in texture.
• It is used in varietal identification.
• It accounts for 10% of the dry grain weight. The thickness can vary with barley variety, with thin husks comprising 9% of the grain weight and thick husks up to 13%.
• Cereals that have no husk, such as wheat, can have 10% more starch than barley.
• It is mostly cellulose and silica.