From seeming chaos comes sweetness

When peering into a mash vessel and watching the agitator go round in the gurgling mass of brewing liquor mixing with suspended particles of malt, what seems to be pure chaos is actually quite ordered by the melodies and rhythms of thermodynamics and biochemistry. All of these particles are bumping into each other to the throb of the laws of physics, and a marvel occurs before one’s very eyes. Enzymes primarily created during malting are moving around this aqueous suspension and facilitating the degradation of long polymers and other complex molecules over a remarkably short amount of time.

Though it is a marvel, nature does not work miracles. Maltsters and brewers must take care to make it happen by carefully producing malt and wort under certain conditions. Plus, brewers must understand how to tailor the process to the malt they’ve received at their breweries. As a natural product, it can vary. This is why learning to read and react to a malt analysis is an important skill for brewers. Whether the conditions for successful wort production have been met can be measured and objectively evaluated by the efficacy of the process (the available residual and the soluble extract in the spent grain).

Fads, inclinations and decline

Two trends have prompted these thoughts: With beer sales dropping, craft brewers are now looking to leaner techniques to improve efficiency in brewery operations. Another trend sees brewers moving away from gimmicky novelty beers to embrace beers with a higher drinkability, some of which include German and Czech lager culture. A few of them have succeeded.

Around the world, there are different approaches to mashing. Going back millennia in the past – and even up to just a few decades ago in some remote, antiquated breweries – mashing involved making a dough or a thick slurry and then baking it for a long time to denature the starch, cell walls and proteins in a mix of milled and hydrated malted and unmalted grains. The result could be a twice-baked bread or a wet, plum pudding-ish mass. Both would be well-gelatinized and usually mixed with more malt grist and water, to make use of the malt enzymes to further degrade the endosperm’s valuable constituents. Needless to say, this wasn’t very efficient but is highly interesting from a historical perspective.

Nowadays, there are those who value efficiency in addition to maximizing extraction and who plan their breweries and processes accordingly. On the other hand, some are only concerned with making the process as easy as possible. One might call this the “just-add-water-instant-wort” approach. This avoids the use of additional vessels or more complex equipment as well as implementing more complicated techniques.

Coming in thick and hot… and deep

Homebrewers who’ve become craft brewers generally utilize very highly modified malt and mash at one temperature. They mash in thick (1 : 3.5 or less) and high (≥ 65°C), riding the fence between α- and β-amylase. Whether they’re aware of it or not, the thicker mash at these higher temperatures keeps the enzymes, especially the β-amylase, from denaturing as quickly over the duration of their long single temperature rest. For many, the mash tun is a direct-fired black box into which one puts hot water and malt grist and out of which comes sweet wort (given the fact that mash-lauter tuns are the norm among craft brewers). A ‘multi-step rest’ often means adding a mash-out step to their single temperature infusion.

The grain bed is often too deep to be efficient during lautering (max. depth should be 40 cm, normally 32 cm with a dry mill), so a lot of soluble extract is left behind in the mash-lauter tun. Those following the new trend of brewing Central European pilsners and who purchase European malt without altering their mashing equipment or practices need to take time to pause and reflect.

In order to make this process not only more efficient but also to improve it from a quality standpoint, a different approach would be highly advantageous.

Not just saving a few farthings

The authors have been astonished when visiting North America to hear more than once that ‘a protein rest is required if the percentage of protein in the malt is too high.’ Rather, it is the degree of protein modification (characterized by the total N, Kolbach index, soluble protein, FAN, Hartong VZ 45°C, among others) that convey whether a protein rest is required – as highly modified as most malt is in this part of the world, likely not!

Maltsters regulate how much degradation of the nitrogenous substances occurs during germination. There is tremendous variation among the groups of N-compounds, and some have been made soluble by the maltster while still more become soluble during mashing, though some will always remain insoluble. If protein degradation is insufficient or too extensive, it will have a negative impact on the finished beer. The objectives of a protein rest are to make higher molecular weight proteins available that provide body and aid in foam formation and head retention while also supplying yeast with the proper nutrients in the form of the smaller and much simpler peptides and amino acids. Another goal is to facilitate the generation of the desired range of fermentation by-products in the finished beer.

If very highly modified malt (similar to traditional British malt for pale ale production, i.e., Kolbach index ≥ 42%) is subjected to a protein rest, the spectrum will skew towards the smaller and simpler molecules, which is detrimental to fermentation, body and foam. The excessive amounts of low molecular weight proteins in the wort are one reason that British brewers employ Irish moss in the brew kettle. With its negative charge, the carrageenan attracts and thus causes the precipitation of proteinaceous substances, which can then be eliminated in the whirlpool. However, the lack of high molecular weight proteins means foam formation is lacking. Body in a delectable British ale is normally provided by crystal malt.

Bavarian and Bohemian styles

Many craft brewers have become enamored of Central European styles and want to brew them with – for these beer styles at least – malt that is ‘overmodified.’ They also want to employ a single infusion mashing regime. Some feel the need to acquire European malt. Purchasing malt from Europe but mashing like it’s a hazy IPA simply won’t do. No Bohemian pilsner is brewed even with a step infusion. All of them are produced with a single, double or, in one case, a triple decoction. It is understandable if decoction is not in one’s wheelhouse but at least mashing in thick and low in an unheated mash tun and diluting with hot liquor while stirring through the various rests would be useful.

One doesn’t even need to purchase malt from Europe. Simply find a less highly modified, very light-colored malt and mash in at around 61 to 62°C somewhat thicker and raise through to 70°C to end at a grist to liquor ratio of about 1 : 4, so the enzymes aren’t destroyed over the course of the rest. Mashing out would be useful, too. For this to work, the protein content of the malt would ideally be ≤ 10.8% and the Kolbach index between 39 and 40%. Though somewhat inhibited at these higher temperatures, the carboxypeptidases as well as the glycoproteids should provide enough high molecular weight protein and FAN. The malt should also possess a friability of more than 85% with fewer than 2% completely glassy kernels. Ideally at least a single decoction would be possible, since a decoction between the two saccharification rests is advantageous. This will digest the starch more effectively, increasing the final attenuation. A second decoction to the mash-out temperature increases the beer’s drinkability. The mash pH should also be adjusted to between 5.4 and 5.5.

A few simple modifications can optimize brewhouse operations, serving to improve quality and efficiency, especially when brewing Central European lagers.

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