BASICS OF SPIRITS PRODUCTION ●

have broken this trend. Annual produc- tion output from production facilities processing both un-malted and malted Grain spirits , or commercial enzymes is well in excess of this 10Mla, with some hav- ing capability to produce more than ten production times this volume. This is the type of process employed to produce Scotch grain , grain Milling and neutral alcohol and the signifi cantly larger-scale operations of the fuel alcohol industry. Starch in its natural en- vironment is an energy source stored in the endosperm of the cereal grain and is generally bound, to varying extents, with proteins in and around the endosperm. In its fi xed state it is insoluble in water and requires vigorous treatment to make it more readily available for conversion to fermentable sugars in the conversion or mashing processes. Accessing this fi xed starch is highly energy-intensive, and the two primary methods are by cooking with water istock.com/PytyCzech at high temperature and pressure, or By Billy Mitchell by physical/mechanical treatment by breaking down to very fi ne fl our by ham- mer milling. These will both be explored In this, the third article in the series to support those in more detail later in this article. studying for the General Certifi cate in Distilling, we look Figure 1 gives a high-level sim- ple schematic overview of these at the plant and processes used in the production of spirits processes. As already stated, these from primarily non-malted raw materials. We will also look processes require signifi cant input of either thermal or physical energy in at some of the processes employed to hydrolyse starch in the form of either high-pressure steam non-malted grains and how that hydrolysed starch can be and/or electrical power. Accessing the starch also requires input of a signifi - converted into fermentable materials for conversion into cant volume of water. Combining the alcohol in the subsequent fermentation process. throughput of raw materials, water, thermal and electrical energy in these n these processes the starch source This is not an issue in the process- processes provides a great opportunity Ioriginates from non-malted cereals ing of 100% malted barley, as excess for energy recovery and reuse, and such as maize and – and the enzymes are present in this mash bill. this is another key factor in delivering enzyme source originates from high- Use of insuffi cient or commercial effi cient production of product. enzyme malted barley or via a com- enzymes will result in loss of effi ciency mercial enzyme source. Specifi cations by failure to convert available starch, The biochemistry for these were discussed in the fi rst while use of excess enzyme will add In the article Raw Materials for Cereal article in this series, Raw Materials for unnecessary costs to production. Distilling I reviewed how amylase and Cereal Distilling (Brewer and Distiller amylopectin are the two forms of starch International, June 16). General principles that are produced by cereals and stored In the production of Scotch grain The ultimate goal of each spirits in the endosperm. I also discussed the whisky only endogenous enzymes from producer is to produce the maximum general composition of the main cere- malted barley are permitted, as defi ned volume of alcohol, of the required qual- als used in sprits production and gave in the Regulations. For ity, for each type of mash bill using the an overview of many of the raw material production of non-Scotch grain whisky, minimum volume of water, utilities and specifi cations employed. In this article exogenous enzymes are allowed. These energy. This is a fairly simple state- we will focus on the two main cereals can be used both in the starch hydrolysis ment of intent but delivery of that goal used in grain spirits production, namely and conversion processes and can totally in these processes can be challenging. wheat and maize. replace endogenous malt enzymes if re- One of the main reasons for this is due While the starch is provided by quired. One key element to be carefully to the scale of the operations involved. the wheat and/or maize, the enzyme considered if using malt or commercial The total annual output from an av- source can be provided through the enzymes, or a mixture of both, is to en- erage facility processing 100% malted inclusion of a relatively small portion sure the concentration of these enzymes barley, is generally considerably less of high-enzyme malted barley or by is such that effi cient conversion of starch than 10Mla (million litres of alcohol) per the use of commercial enzymes read- to fermentable materials is achieved. year, however, some newer facilities ily available to this industry. Endog-

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– this term is used to describe the com- bined activity of these two enzymes. Grain storage General storage stock To fully understand these enzymatic actions on the amylose and amylopectin starch structures, you should firstly re- Grain cleaning Removal of debris acquaint yourself with these structures as outlined in Raw Materials for Cereal Distilling. An amylase is an enzyme that catalyses the hydrolysis of starch into Accurate weighing of raw Grain weighing sugars – let us now review the main two material amylases involved in this process.

Beta-amylase Beta-amylase is an exo-enzyme, which Cooking process Low temperature process starts at one end of a chain of glucose molecules and works its way along the High enzyme malt Commercial enzyme chain splitting off two glucose units at a time. Two glucose units joined together form the structure of maltose and so beta-amylase will produce mainly malt- ose from a chain of linear glucose units, Mashing fermentable although some glucose and maltotriose sugar may also be liberated due to different chain lengths. Beta-amylase action ceases whenever a branching point is Batch or continuous cooling reached on a non-linear glucose chain. process From this it can be assumed that the enzyme working alone on starch (amylose and amylopectin) Figure 1: Grain preparation and mashing will convert all the linear amylose enous enzymes must be used when reaction and no other. Because of this, primarily to maltose, although it will producing Scotch grain whisky while the breakdown of a complex organic only hydrolyse around 50% of the commercial enzymes with or without material frequently requires a group of branched amylopectin. In the case of endogenous enzymes will be used in enzymes working together, since each the latter, the ends of all the branches other spirits production. one will confine itself to only one part will be ‘pruned’ until a dividing point Enzymes are protein-like sub- of the material breakdown. is reached leaving a substance called stances associated with all living A similar situation arises in the beta-amylase limit-dextrin. material. They possess the property of breakdown of starch by malt enzymes. being able to rapidly carry out chemi- At least two enzymes are required to Alpha-amylase cal reactions under normal conditions deliver anything like a 100% conversion Alpha-amylase acts in a completely of temperature and acidity – reactions of starch to fermentable sugars and different manner. It is an endo-enzyme which would generally be impossible these are called alpha and beta-amyl- which makes random attacks on the in their absence except in an extreme ase. Historically before enzymes and starch molecules eventually producing environment of very high temperature their activity were fully researched and fragments of a length between six and or the extreme limits of pH. Enzymes understood, the action of malt enzymes twelve units from both amylose and are highly specific – one particular on starch was referred to as being amylopectin. If alpha-amylase were to enzyme will carry out its own specific brought about by the ‘diastase’ of malt act alone on whole starch, then for all

When the malt has been Starch consists of a long This sugar is called mashed with water, enzymes chain of sugar(glucose) maltotriose. It will ferment are released which attack molecules linked together slowly the links in the starch chain at the points shown by There are some branches in This sugar is called arrows the chain maltose and ferments Alpha Amylase attacks at quickly random points in the chain. There is a high level of activity during mashing This sugar is a dextrin and it will not ferment Beta amylase attacks at Maltase has a very the second to last link in low level of activity the chain This sugar is called glucose and it ferments very quickly

Enzyme action and structure of glucose, maltose and maltotriose

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practical purposes the end result would be to produce a number of multi-unit glucose units i.e. dextrins, which would Grain storage not be fermented by yeast, and so the presence of both enzymes is essential. Since neither alpha or beta-amylase can break the branching points of amy- Grain cleaning lopectin these remain – and even the combined action of both enzymes leave a small percentage of starch in the form Grain weighing of un-fermentable limit-dextrins, other active limit-dextrinases will eventually break these down during fermentation. Rough milling or whole The main objective in mashing is Batch or continuous Grain preparation to convert the starch into fermentable grain sugar; other enzyme-driven protein breakdown reactions are also relevant for yeast nutrient, yeast growth and fla- Hot water Grain cooking Cooker discharge vour development during fermentation. Further more detailed reading on the function of enzymes can be found in an excellent article in the Brewer Energy recovery Mashing conversion and Distiller International, Volume 11, Issue 10 date 10 October 2015 by Tim O’Rourke. Figure 2: Cereal cooking Cereal grain preparation use a semi- continuous type of cooking cooked whole – some key elements of In this section I am going to give an process through a long loop. the cooking process include the cereal/ overview of the two main processes Others use only water as process water (liquor) ratio, sometimes referred which allow spirits producers to access liquor while others use alternative hot to as cooker dilution, the maximum and release the fixed starch from the liquor streams from other parts of the temperature and pressure of your cook cereal grains. These are cooking at production process to replace some if process, how you vent incondensable high pressure and temperature and the not all the water input. Some proces- gases produced during the cook phase physical/mechanical breakdown of the sors will only cook whole cereal corns and how you discharge the cooker from cereal grain to very fine flour by milling. while others may employ a course its maximum pressure to atmosphere or Starch gelatinisation is the process milling process. Obviously the temper- through a vacuum system. of breaking down the intermolecular ature and pressure will be altered to Ensuring efficient venting of incon- bonds of starch in the presence of accommodate the different plant and densable gases throughout the cook water and heat, allowing the hydrogen processing options. will mean that the relationship between bonding sites to take in water. Ge- Table 1 gives an overview of the ce- the temperature and pressure follows latinisation improves the availability of real processing rate required for produc- that detailed in traditional steam tables starch for amylase hydrolysis. Gelati- tion hours of 24 x 7, operating over 50 – failure to vent these gases will deliver nisation temperatures are different for working weeks. It also assumes a 10% a lower temperature for the correspond- each type of cereal being processed, inclusion of high-enzyme malt in the ing steam pressure and could result in therefore your plant and processes re- mash bill with a predicted overall aver- undercooking of raw materials. quire in-built flexibility to maintain and age yield of 385la/tonne grain processed These conditions will be specific achieve efficient production. on an ‘as is’ basis. I use this for com- to your own plant and operations and If you chose to process either wheat parative purposes only, this may not be much like many of the processes will or maize, this is important to those representative of your own operations. have been evolved over many years using a cook process. In the low-tem- These rates show a significant vari- as knowledge of plant and processing perature fine flour process the starch ation in the cereal processing require- conditions developed. is not gelatinised in this way, as the ments as determined by production The scale of these operations and starch granules are damaged by very output. To achieve a constant delivery of the high throughput rates make this fine hammer milling which makes them this rate of processing requires instal- cooking process very energy intensive, more accessible to enzyme attack. lation and operation of multiple cookers particularly with respect to thermal Figure 2 gives a simple schematic of which, used consecutively, will ensure energy input. There are many excellent a traditional cooking process using only that these individual batch operations Annual Cereal Required Processing Rate water as the main process liquor. It is can be seen to deliver a continuous Capacity (Mla) (tonnes) (tonnes / hour) important to note that spirits producers stream of cooked, hydrolysed starch into do not use identical plant or processes the mashing process. The capacity of the 30 70,130 8.5 to achieve starch gelatinisation by cook- individual cookers will again reflect the 60 140,260 17.0 ing – there is no one size of plant or scale and output of your operation. 90 210,390 25.5 process fits all. Some producers use The cooking conditions employed will 120 280,520 34.0 vertical cookers, some producers use reflect the cereal to be processed and Table 1: Cereal processing rates required for 24 x 7 horizontal cookers, some producers whether this has been roughly milled or production over 50 weeks per year www.ibd.org.uk Brewer and Distiller International November 2016 z 33 l BASICS OF SPIRITS PRODUCTION

steam input to raise the temperature to around 70°C, water and/or back set and possibly even a small portion of the malt slurry to reduce viscos- ity, delivers a continuous stream of hydrolysed starch ready for conversion along with the balance of malt slurry or commercial enzymes in the mash- ing process. The very high thermal energy input of the more traditional cooking process Low temperature processing (LTP) at is more than offset by the electrical Cameronbridge, mixing fine flour, steam and demand from the hammer milling water processes. The high temperature Hammer mill produces very fine grind. © BMK Wikimedia and pressure (144°C and 3.4bar) of the traditional batch cooking process examples of very efficient energy re- is replaced by this low temperature covery processes employed to ensure methodology – maximum temperature that thermal energy is maintained at of this process is around 70°C. lowest possible input by recovery and There are a number of issues reuse of flash steam and hot water. which can arise if optimum process Much like everything in spirits pro- conditions are not maintained, regard- duction they will be different for each less of whether you employ a cooking spirits producer but will have the same or low temperature milled process. goal – to maximise energy recovery These can all lead to a loss of ef- Supply side of LTP system, showing steam and water control and reduce raw energy input. ficiency or subsequent downstream processing problems which will not be occur. Overcooking of cereal (particularly Low temperature processing overcome later in the process. These at high temperature and pressure) can Figure 3 gives a simple schematic of can include balling of the grain if not result in Maillard or browning reactions the processes involved in this more adequately hydrated or mixed, and – these are complex reactions between modern low-temperature approach starch retrogradation if cooked uncon- sugars, dextrin and proteins and/or to accessing and releasing the cereal verted starch is held too cool for long amino acids resulting in very dark pig- starch. High throughput hammer mills periods of time. mented tightly bound complexes that do with a screen size of circa 2mm are Undercooking of cereal, if correct not readily undergo enzymatic conver- employed to produce a very fine flour water/cereal ratio or maximum temper- sion to fermentable sugars. which, processed along with a limited ature pressure is not achieved, can also There is also the potential for microbiological contamination to reduce the overall efficiency of these biochemical processes, with impact on Grain storage both overall alcohol yield and product quality. All elements of the process plant must be cleaned regularly. A significant number of poten- Grain cleaning tial health and safety issues exist in these processes if the plant and control philosophy are not properly Grain weighing risk-assessed, designed and installed. The handling of cereals through grain storage, grain cleaning, milling and weighing can create the potential to Grain milling Hammer mill fine flour release significant quantities of grain dust into the atmosphere. The plant must be designed to minimise this risk Steam and built to satisfy the requirements of The Dangerous Substances Explosive Water Low temperature process Mashing conversion Atmosphere Regulations (DSEAR). The cooking plant and feed steam systems and product discharge streams must Process liquor be designed and built and operated to satisfy the Pressure Systems Safety Regulations (PSSR). Malt slurry Obviously these processes con- sume a considerable amount of steam, electricity, compressed air and water Figure 3: The low-temperature processing and your utilities plant and installation

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must be designed and built to satisfy this the potential for temperature hot spots demand. Each utility stream and raw and deactivation of available enzymes. material supply must have weighing and One of the key control features metering systems installed to ensure of efficient mashing depends on accurate accounting of consumption and how the high-temperature cooked processing in each unit operation. starch stream is cooled and deliv- ered to the mashing plant to ensure Mashing that the mashing strike temperature The principles of mashing in grain is achieved. This heat removal is spirits production is the same as that delivered by a variety of processes for spirits produced from 100% malted including cold water addition, vacuum barley processing. Mashing is the processing to reduce temperature and name given to a very important pro- other heat recovery processes. Modern mash vessels at Diageo’s Cameronbridge Distillery cess in both beer and spirits produc- The low-temperature starch pro- tion where the key process is to allow cess is a continuous system where the correct ratio of high enzyme malt to enzymes (endogenous from malted milled grist, water and hot recycled cereal ratio. A clear purchase specifi- barley or commercial enzymes) to act liquors is pumped from the mixing cation for high enzyme malt is essen- on the released cereal starches and hydrator to the mashing vessel where tial - see my Raw Materials article. convert them into fermentable sugars. malt enzymes are added in a similar Further reading on Grain Spirits As with all production activities fashion to the cook process. production can be found in the second in the spirits industry there is no one The majority of these more modern edition of Whisky, Technology, Produc- design of plant or scale of operation mashing processes have no solids tion and Marketing, edited by Inge employed. Historically, there was a removal and all the solids from the Russell and Graham Stewart. This traditional three or four water process cereal and malted barley are fed for- is a book that should feature on the used to extract the soluble ferment- ward for cooling prior to fermentation. bookshelf of any serious student of the able carbohydrates produced during Both the cooking and low-temperature spirits industry. There is also excellent mashing after the cereal starch and processes can utilise either green or background information contained in enzyme source had been mashed dried malt as the endogenous source the learning material and syllabus for together. The first two waters of this of enzymes – key here is to ensure the the General Certificate in Distilling. batch process were fed forward to optimum ratio of malt to cereal (malt fermentation while waters three or inclusion rate) and also to provide Some more follow ups! four were retained as first and second a robust wet or dry milling process There is no one size or design of plant waters for the next mash. for the malt element. Holding a cold that fits all producer’s requirements Like the malt spirits industry, the malt slurry solution for a prolonged – here are some follow up pointers to spent cereal and malt solids were re- period of time is not recommended as help embed your learning: moved at the mashing process. These this material is readily susceptible to • Fully understand the capacities and old, traditional mash tuns had rake microbiological contamination. capability of all plant used in cereal gear driven through the cereal and Both the cooking and low-temper- starch provision and mashing. What malt bed to extract the soluble carbo- ature processes can be easily modified are the pinch points in your operation? hydrate. These processes have been to produce non-whisky spirits, where • How is the plant cleaned and superseded by more modern mashing the endogenous malt enzymes can be maintained? What are the real key techniques, although the traditional partially or fully replaced with commer- maintenance activities and how do they operations can still be found, albeit in cial enzymes. These type of processes impact on production? a limited fashion. can be readily seen in the fuel alcohol • What are the key risks in the process Modern mashing processes include or grain neutral spirits industries. and how are they mitigated? Do you continuous mashing, where batch or All of the mashing processes are require any particular permit require- continuously-cooked starch is fed into susceptible to contamination through ments to operate this plant? a process where the malt enzymes microbiological activity and so man- • Talk with your quality department or are continuously added and there is ual and/or fully-automated clean- laboratory team to more fully under- a limited retention time in the mash- ing processes must be employed to stand the key analysis and results from ing plant really only determined by ensure plant is fully cleaned at regular these processes. the removal rate of to cooling intervals. Failure to achieve this can • What are the major energy recovery and thereafter fermentation. A more and will result in a drop off in mash- processes and how can they be af- traditional batch version of the above ing pH with resultant fall in conversion fected during processing? process can also be found where the efficiency. Enzyme activity is not totally • What are the key accounting points mash is held for a predetermined time deactivated after mashing, resulting in in this process for both raw mate- at the required mashing temperatures. some secondary conversion of larger rial and energy consumption and how The vessels now used in mashing sugars during fermentation. It is also are they used to calculate efficiency vary considerably from fairly squat, worth noting that very poor conver- measures? large-diameter to taller, small-diame- sion efficiency in the mashing pro- ter tanks. The key design features are cess cannot be fully recovered during Answering these questions and posing to ensure a real mix of the starch and fermentation, with resultant impact a few more of your own will ensure enzyme streams to ensure homogene- and additional processing problems. It you will have a more detailed under- ous mixing of both solids and tempera- is vitally important to control mashing standing of these two very important ture. This intensive mixing will negate temperature, plant cleanliness and the process. www.ibd.org.uk Brewer and Distiller International November 2016 z 35