Chapter 9


Double-mash Infusion System

The double-mash infusion system is the most widely used system in North America. This system prepares two separate mashes. It utilizes an adjunct cooker (i.e., cereal cooker) for boiling adjuncts and a mash tun for well-modified, highly diastatic malts. Most adjuncts must be boiled separately to gelatinize the starch. If pre-gelatinized adjuncts (e.g., flakes) are used, no boiling is required in the adjunct cooker. In this case, the flakes can be added directly to the mash tun during or at the end of the protein rest (11).

Adjunct Cooker

The first step, before adding adjuncts, is to mash-in a small quantity of barley in the hot water of the adjunct cooker. The alpha-amylase of the malt will hydrolyze the gelatinized starch, rendering the cooker mash fluid enough for pumping.

Mash Tun

About the time the adjuncts are being added to the cereal cooker, the malt and water are added to the mash tun to begin a peptonizing rest within the same range, 38 to 50C (11). After 15 to 30 minutes of peptonizing, the temperature is raised to 50C.

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