Science | Enzymes

SCIENCE

IT WILL ALL COME OUT IN THE WASH

IN THIS PIECE ADAM JOHNSON, EUROPEAN TECHNICAL SALES AT MURPHY & SON, LOOKS AT ENZYMES AND THEIR ROLE IN THE DISTILLING PROCESS.

Malt is a fantastic thing. The maltster has prepared for the distiller a selfdisassembling starch package, where the package even assists in producing wort for fermentation by forming the filter bed. The enzymes included in the grain are capable of completely degrading the starch at ambient temperatures {1}. This may be the case but in distilling, a compromise is always found during processing as you are trying to meet various and sometimes conflicting goals. Before looking at exogenous enzymes it is worth looking at what is already available from malted barley.

As the barley grain is coaxed into germination through the malting process the starchy endosperm degrading enzymes are produced: alphaamylase, endo-beta-1,3:1,4 glucanases, limitdextrinases, endoproteases & Xylanases. (F.G Priest, GG Stewart Handbook of Brewing). Unmalted barley contains beta-amylase and peptidase enzymes.

Malting barley for distilling is a balancing act of trying to achieve maximum levels of fermentable extract whilst retaining the flavour and aroma characteristics essential to malt whisk(e)y {1}. This author does not want to get into spelling debates, but will use whisky for everything for the remainder of this piece. Pale ale brewing malt and pot still malt may have some nuanced differences, but they are both essentially well-modified, plump & pale malts.

For Scottish grain distilling, high Diastatic Power malts are used. This is because other unmalted grains are used to provide the majority of the starch.

They lack the required enzymatic activities & without external assistance they will not be able to convert this starch to fermentable substrate.

High DP malt enables the distiller to convert this whilst remaining compliant to the Scotch Whisky Act. One of the key distinguishing features between wort and wash production vs wort and beer production is the wort boil & lack of it in distilling.

From an enzymatic point of view this has a dramatic effect on the wash composition as enzymes remain active

Scotch whisky producers are much like the brewers in Germany and have gone to some extreme measures to make a great product despite being constrained by legislation

TABLE ONE: RULE OF THUMB GELATINISATION TEMPS Cereal Typical temperature range for Gelatinisation °C

Maize 62-80

Sorghum

Barley

Barley Malt

Wheat

Rye

Oats

Rice 69-75 Small Granules 51-92 Large Granules 60-65 64-67

52-66

49-70

52-64

61-82

Potato 56-71

(Adapted from Brewing Science and Practice DE Briggs) {2} Due to the cellular structure “Cook temps” for the cereals in bold are higher than the reported gelatinisation temps throughout fermentation. Although a range of mashing regimes are used, at typical mashing temperatures starch granules gelatinize, dissolve and endogenous enzymes rapidly degrade this starch to glucose, maltose, maltotriose and dextrins ranging in length.

Wort boiling fixes this wort composition by denaturing the malt enzymes. Primarily brewers are concerned with alpha-amylase & beta-amylase activity to produce the required liquefaction and saccharification, distillers squeeze extra fermentability out of the wort due to preserved activity of limit dextrinase in combination with the pH drop during fermentation {1}. At Herriot-Watt University malting professor James Bryce named limit dextrinase as his favourite enzyme and from a scotch whisky distillers’ perspective it makes sense.

Even with this activity not all limit dextrins are rendered fermentable in scotch whisky production. Some Scotch distillers use commercial enzymes in the lab to benchmark against their process, ensuring they are pushing the boundaries of what is possible without exogenous additions. With malt being such an amazing raw material, it does pose the question why would you need to add non-malt enzymes to the distilling process? The simple answer is that a distiller does not need to, but the many benefits mean many want to.

Malting is an energy and water intensive industry plus barley is around half the price of malt. When approached like this, the economic, agronomic and sustainability arguments become strong for non-malted adjunct use.

It is a mistake to over-engineer just for the sake of it. Simplifying equipment and processing is a rewarding exercise.

Exogenous enzymes are very useful tools that can be utilised to fulfil specific tasks or benefits.

Carbohydrates: Ground grain/corn Starch Glucose Sugar

Proteins: Soy bean meal Gluten Corn steep liquor

Salts: Phosphates Sulphates Ammonium salts Sterilisation

Seed fermenter

Mixing of nutrient medium

Inoculation Flask

Air

Figure one: The enzyme production process Pump Sterile filter Cooling water

Fermented broth for recovery of enzyme

and unmalted cereals are desired for the process. They are also simple to ship, store, dose and use. Dose rates can be incredibly low considering the benefits.

Rule of thumb gelatinisation temps (Adapted from Brewing Science and Practice DE Briggs) {2}

Enzymes are biomolecules that catalyse reactions, lowering activation energies and speeding up the rate of reaction. As biomolecules there is nothing “unnatural” about them in fact the opposite is true. Nature has developed them, and they are essential to nature.

Mankind simply utilises them as a tool. It is true that modern biotechnology has allowed for genetic manipulation but as the drinks industry has for the most part resisted GMO technologies, we will not go down that rabbit hole in this article. Typically, enzymes will be manufactured in a way that would be very familiar to brewers & distillers: Utilising raw materials -> Mixing to an aqueous form -> Utilizing microorganisms, engineering equipment & heating and cooling functions -> Packaging Final product TABLE TWO: A BRIEF OVERVIEW OF THE DISTILLERS ENZYMATIC TOOLBOX

Enzyme Function Notes

Alpha Amylases

Exogenous forms have many different temperature and pH optima Starch Liquefaction, viscosity reduction By random hydrolysis of starch u Allows for use of non-malted adjuncts #* u Better suited to certain adjuncts e.g. higher gelatinisation temps u Potential savings for money, energy and emissions u More Flexibility

Beta-Glucanses, Xylanases, Cellulases & Hemi Cellulases Viscosity reduction u Allows for use of non-malted adjuncts#* u Potential savings for money, energy and emissions

Glucoamylases

Proteases Saccharification

Readily available nitrogen for the yeast u Higher Fermentability u Higher Alcohol yield u Efficiency savings u Higher alcohol yield u Quality and efficiency benefits

# Due to its low levels of essential enzymes (-amylase, proteases and Beta- glucanases) together with a relatively inaccessible starchy endosperm, high inclusions of unmalted barley (>20%) in the mash (without the aid of commercial enzymes) can lead to problems such as low extract yields, high wort viscosities, decreased rate of lautering & fermentation problems {3} * The major difficulties in wort production with high levels of wheat include an increase in viscosity, slower wort separation {3}

Figure two: Differences of amylose and amylopectin

R1 R 2 R 3 R 4

NH 2 – CH – CO – NH – CH – CO – NH – CH – CO – NH – CH – COOH

Amino-acid

Aminopeptidase

Figure three: Proteases enzymes Endoprotease

Exoproteases Amino-acid

Carboxypeptidase

The distilling process is a great area for the application of accumulated marginal gains. In a grain distillery increasing ABV from 9.6% to 11% results in and increase of alcohol yield from 370-385L/t Grain.

The processing can be broken down and examined and areas can be looked at for improvement. E.g. Is spirit yield & energy consumption good? Can it be better? Are raw material costs good? Can they be better? Therefore, many distillers use exogenous enzymes to improve product and/or process.

ABOUT THE AUTHOR

Murphy and Son is not an enzyme manufacturer, but we have found success as an enzyme supplier as we can partner with a wide range of manufacturers who offer the best solutions & as qualified brewers and distillers we can work with the customers to get great results. For example, Trizyme is a blend of alpha amylase, Beta-glucanase and protease activities. Distillers can use this with significant non malted barley & adjunct usage and measure results compared to separate additions.

As a single product to purchase, store and apply to the process there are operational benefits. We can even tailor formulations for their specific process.

different perspective than many distillers & we have some slightly alternative ideas we would like to investigate with distillers working from grain to glass. “Burtonised” Ready Hardened Malt- With our expertise in water treatment for the brewing industry spanning over 130 years we are developing malt with an increased acidification potential and higher calcium levels. We believe this will produce benefits to the mashing process. We would also like to work with some distillers to tailor our existing treatments to producers who are not constrained by Scotch whisky.

We are also fortunate to have access to a wide selection of farmhouse yeast strains, if you have come across “Kviek “strains before you will have noted they have extremely interesting fermentation profiles as they are much more tolerant to high temperatures they can therefore ferment even faster than typical wash fermentations 24 hours is common for farmhouse brewers (Historical brewing techniques LM Garshol) We would love to work with some distillers with a curious mind in these projects or others that you think will spark our curiosity. Connect via my Linkedin profile: https://www. linkedin.com/in/adam-johnson65827595/?originalSubdomain=de Cheers to all the distillery workers keeping our spirits up during a very difficult time!

REFERENCES

1. A review of malting and malt processing for whisky distillation George N. Bathgate* https://doi.org/10.1002/ jib.332 2. Brewing Science and Practice, DE Briggs, CA Boulton, PA Brookes & R Stevens. 3. Brewing New Technologies CW Bamforth 4. 125th Anniversary Review: Developments in brewing and distilling yeast strains Graham G. Stewart Annie E. Hill Inge Russell https://doi.org/10.1002/ jib.104

Article author Adam Johnson and his sister (left) on their very first visit to a distillery