Striking out at bursting granules

We can imagine that perhaps a few of the regular readers of this engaging periodical might be waiting for their strike liquor to heat up in preparation for mashing in. Perhaps, part of their routine might be to peruse this issue’s pages over a coffee while they wait. They might also want to begin casting a glance over their latest malt analysis to find what might be entered under the rubric of ‘gelatinization’, which could include ‘onset temperature’, ‘peak temperature’, ‘end set temperature’ and/or ‘pasting temperature’. One would do so in order to observe whether the old tried-and-true mashing regime might need to be tweaked with that new lot of malt that just arrived.

Perhaps you’ve heard comments such as: “The farmer and maltster, they take care of me. They deliver well and evenly modified barley malt high in extract and low in protein which allows me to brew excellent beers with minimal effort in the brewhouse.” And I’m sure they do an outstanding job. Nevertheless, brewers might still want to dust off and delve into the old tomes in their bookshelves or look at the latest research, for instance, in the journal BrewingScience, to refresh both the viability and vitality of their knowledge of mashing theory and to propagate the efficacy of their brewing practice. Furthermore, they may need to altogether abandon their simple single-temperature infusion mashes (gasp!) – or, for that matter, even their two-step β/α infusion. Otherwise, guileless brewers may soon find their lauter run-off somewhat gyleless – pardon the pun, but it’s true. Creativity could be the best cure for poor brewhouse efficiency … in this case caused by climate change.

To briefly clarify, a non-brewer is exposed to gelatinization when making oatmeal porridge or baking bread. By boiling crushed or cut oats in water, one becomes aware of a sudden transformation in the grains. They’re discrete individual flakes until at once the pot is filled with a very viscous, sticky, indistinct mush. Freshly baked bread is soft and fluffy for the same reason. Stale bread is partially ‘un-gelatinized’ due to starch retrogradation. The amylases in the brewhouse mash have almost no access to the endosperm’s long α-glucan chains until this ‘onset temperature’ has been surpassed.

And as one musician from barley-growing country put it, “The times they are a-changin’” – and fast! Almost as quickly as the barley endosperm does during germination. The longstanding mashing regime might’ve been ‘tried’ with different malt and thus not quite so ‘true’ anymore. Climate change has thrown a spanner in the works in the form of the shifting conditions under which malting barley is now cultivated. These fluctuations are moving in both a hotter and drier direction. So, what’s this mean for malt?

Climate change, malt and the double helix

The barley endosperm holds enough nutrition for the little plant inside to start its life, and this energy is packed about as tightly as Mother Nature can viably pack anything. In “The other double helix”, the authors compare how starch and DNA store huge amounts of energy and information, respectively (and hydrophobically), in a tiny space.

Growth in starch granules resembles that of tree rings. As they grow concentrically outwards, they develop amorphous rings composed of single helices containing α-1,6 branches. These layers, or lamellae, form the less dense rings more susceptible to enzymatic degradation. The rings of greater density consist of linear double helices of amylopectin. These are so dense that they are quasi-crystalline and provide the characteristic wedge shape essential for compactly storing the energy in the endosperm.

For this reason, during mashing, the brewing liquor will enter the amorphous layer at a snail’s pace but will not penetrate the crystalline layer at all until the mash has gone beyond the gelatinization temperature. If gelatinization does not occur, brewhouse efficiency drops like a hydrometer in pure alcohol. However, once above said temperature, the double helix unwinds and, forming a gel, becomes quite viscous. This unwinding of the helices allows the amylases to rapidly get at and break down the starch.

How these concentric rings are laid down in starch granules as the barley grows is dependent upon the weather conditions during cultivation. It turns out that heat and a lack of precipitation during the life cycle of barley make the crystalline rings even more difficult to unwind. There is a fine balance, as with everything in brewing: Brewers must gelatinize the starch without denaturing the amylases they depend upon to convert the mash. The spanner that’s been thrown into the works is that, in her anger at climate change, Mother Nature has switched the script on brewers, and maltsters can’t do anything about it. The gelatinization temperature might be far above the β-amylase temperature optimum, closer to the α-amylase optimum. This means that the β-amylase, which is denatured rapidly at around 65°C in the mash, doesn’t have a snowball’s chance in a hot wort kettle to get at most of the starch because the gelatinization temperature is 68°C or even higher. Consequently, under these circumstances, brewers don’t have much of a maltose rest.

Brewers have the capacity to resolve this not-so-sticky situation with ingenuity, flexibility and the right equipment or perhaps even by other means. A single decoction at the right point in the process can greatly increase efficiency. For example, by first mashing in at a temperature of 45°C or so, a decoction can then be pulled. At each of the amylase rests, the brewer pauses the decoction mash briefly to further increase efficiency before raising the temperature to 95°C or above. Boiling isn’t necessary. This non-enzymatic ‘thermal digestion’ of the starch unwinds the crystalline helices in that portion of the mash, regardless of how tightly they’re wound, and helps to break them apart. In returning this back to the main mash, all of this starch is wide open to the amylases. The temperature of the entire mash rests at around 62°C to facilitate saccharification with the still ample contingent of enzymes. Brewers can get creative with cold brewing liquor additions too, in order to maximize this effect.

Another decoction is also possible afterwards. Surprising to some, a second decoction tends to make beers more palatable, well-rounded. Equipment-wise, though not optimal, one can mash-in in the wort kettle and send the rest mash to the lauter tun, if need be.

Alternatively, one can mash in thick with two-thirds of the grist slightly above the so-called onset temperature and remain there until gelatinization is achieved. This allows the starch to be made available to the enzymes. Afterwards, cold brewing liquor is added along with the additional third of the grist. The mashing regime can then be carried out with the full complement of enzymes from the one-third and those that still remain in the two-thirds.

Or bacteria-derived amylases that are more thermostable can be utilized for brewers who want to/are allowed to use them. For example, β-amylase with greater thermostability has been derived from Clostridium thermosulphurogenes and can be purchased for the purpose of mashing.

Given that climate change is upon us whether we like it or not, more flexibility – and creativity – in the brewhouse may be essential to maintaining one’s accustomed level of quality and efficiency. Under these conditions, a decoction regime or other mashing techniques or even exogenic enzymes might be the key to maintaining or perhaps improving the quality of one’s beers.