The Barley Malting Process – Steeping

The Production of Malt from Barley employs 6 main steps:

• Barley Selection: Barley is selected on the basis of variety, the location in which it was grown, and physical and analytical evaluation, including moisture content, protein content and germinating capacity.

• Storing, Cleaning and Sizing: Barley should be segregated in storage by crop year and variety. Lots may be further segregated according to protein level, sizing and geographical origin. The goal is to keep the Barley in sound condition. Cleaning and sizing prior to Steeping results in Barley kernels of uniform size and predetermined width, free of broken Barley and foreign seeds.

• Steeping: The purpose of Steeping is to evenly hydrate the endosperm mass to a moisture content of approximately 45%, to allow uniform growth during germination. Steeping also cleans the Barley by washing, and eliminates lightweight kernels (which would obviously raise to the top and can be skimmed off). Steeping is generally considered to be the most crucial step in the production of high-quality Malt.

• Germination: The kernels are allowed to grow under controlled temperature and humidity conditions.

• Kilning: The kernels are dried by exposure to heat and airflow. Kilning stops growth, produces flavor, aroma and color in the Malt, and results in a stable storable product.

• Cleaning and Binning: The Kiln dried Malt is “cleaned” to remove rootlets and sprouts prior to storage. Many distillers require a minimum period of aging of Malt prior to using it, and many Maltsters will in the same way have their Malt rest and mature prior to shipment – commonly a period of 14 to 30 days in both cases. This aging or maturation period allows moisture to equilibrate (evenly distribute) in the kernel. In the case of Malt supplied to end users, the Malt is then cleaned again prior to shipment.

What are the Objectives of Steeping?

Barley is Steeped in order to uniformly hydrate the kernel and maintain the embryo metabolism without promoting excessive metabolic activity. Uptake of water evenly throughout the kernel is critical, as any unhydrated areas will not be completely modified during germination. The overall goal of Steeping is to provide moisture and temperature conditions that promote the uniform uptake of water so that when the germination process starts, the Barley can be uniformly modified.

How is the degree of Steeping determined?

Three methods are used to determine the degree of steeping:

Cuts through kernels: The amount of gin layer in the endosperm indicates the amount and uniformity of steeping

Ability to resist pressure: A kernel is pressed end-to-end between the thumb and index finger. The amount of pressure needed to press the kernel together indicates the degree of steeping.

Moisture determination by weighing, drying and reweighing: This is the most reliable method to check the first two methods of evaluating the moisture level in the grain.

How is Barley Steeped?

Dry Barley is brought to the Steeping vessel – commercially this would be done by a conveyor or pumped into the vessel as part of a water slurry, but on smaller scale you could use an auger, or just carry the bags by hand (and shoulder). Generally, the receiving vessel is filled with enough water to allow the total volume of grain and water to reach the overflow through of the tank. Usually the Barley is added to the water while undergoing constant and vigorous aeration, which creates a washing effect to remove soil and organisms. It also causes lighter material to loosen and separate from the bulk of the Barley.

After the addition of the Barley to the water – sometimes referred too as “Steeping-In” – the lightweight material that floats to the top of the water, consisting of light kernels and chaff, is removed by floating off into the overflow through. At home you can achieve the same by doing this outside, or inside a blow-up kiddies pool, overfilling the pot, bucket or drum you are using slowly while gently stirring the mixture, causing the lighter material to spill over, but leaving the heavier kernels behind at the bottom of the vessel. Commercially however, water is pumped into the bottom of the tank or sprayed on the surface to direct floating material to the overflow, and manual or automated skimming devices can be used to physically direct floating material toward the overflow through.

Before Barley is placed in the Steeping vessel, an additional step may be taken to clean it in a Barley washer – a device in which mechanical agitation and flowing water forcibly removes foreign material from the grain surface during transfer to the Steeping vessel. Barley washers reduce or eliminate the need for skimming in the Steep tank, and the Barley washing system can speed up the rate at which water is absorbed into the Barley kernel. With some ingenuity, this process can be replicated on a smaller scale at home as well, but in most circumstances it would be unnecessary.

The purpose of Steeping is to raise the moisture content of the Barley from 10-14 %, to 43-47%, before it enters the Germination Phase. The goal is to achieve an even and thorough hydration of the Barley Kernels before they begin to Germinate. The Maltster’s tools for reaching this goal is time, water, temperature, aeration and CO2 removal.

A wide variety of Steeping methodologies are use, depending on the Steep vessel configuration, Barley variety, Barley quality, kernel size, brewer specifications and Maltster preferences. Total Steeping times can vary from as little as 24 hours to 60 hours or more. Steep water application processes range from a single immersion followed by water sprays, to a Steeping schedule consisting out of 5 separate immersions.

All Steeping processes start with an initial immersion that hydrates the Barley to raise its moisture content to between 30-35%. Water uptake occurs at a rapid rate at first , but then proceeds more slowly as the Barley reaches its target moisture content.