| | Introduction | The brewing process | What does the brewer need in malt? | Conclusion
Introduction
Currently, there are as many different beer styles as there are countries in the world, and the quality and characteristics of canadian barley allow for its’ use in producing any beer type. Primarily, all beers can be put into two categories: ale or lager. The difference is in the yeast and the fermentation temperature. Inside each of those categories are a number of different subcategories including low alcohol, high alcohol and a myriad of colours and flavours. Beer is not the only beverage produced using malt; many of the so-called coolers or alcopops have their base in malt. In the US alone there are over 2800 beverages made from malt. New beverages are emerging around the world from Happo-shu in Japan, a low malt very high adjunct beer, to Dimix from Germany, a mix of copper coloured ale and a cola.
The Brewing Process
The brewing process consists of the following steps: milling, mashing, wort separation, boiling, cooling, fermentation, maturation, filtration and packaging. The whole process, from mashing to packaging, takes anywhere from 14 to 35 days. In the mash, coarsely ground malt, together with cooked cereal adjuncts if used, is mixed with warm water. Malt enzymes convert the starch to soluble sugars. The residual barley husks then provide a bed through which the malt extract, called "sweet wort", is filtered using a lauter tun or mash filter. The sweet wort runs to the brew kettle, where boiling with hops adds aroma and bitterness. In the whirlpool, hop residues and other insolubles are removed, and the hopped wort passes through a cooler to the fermenter. En route, yeast is added and fermentation commences. Wort becomes beer. Following fermentation, beer is matured, filtered and packaged. A schematic diagram of a typical brewery operation is shown in Figure 1.
Figure 1. Schematic of brewing process
Milling
As malt is often transported over large distances, breweries must maintain sizable inventories. Malt is shipped at about four percent moisture, with care taken due to its hygroscopic nature. Very cold malt tends to "shatter" in the mill and may cause lower than expected mash-in temperatures, and therefore a period of acclimatization at the brewery is desirable for malt delivered in the winter. Due to the cool and relatively dry Canadian climate, infestation is not an issue with barley and malt shipped from Canada.
Malt is coarsely crushed in a malt mill, designed to keep the husks as intact as possible while producing grist of optimum particle size from the starchy endosperm. The optimum sieve analysis of the grist depends on the type of mill being used and the capability of the wort separation system (lauter tun or mash filter). Mill settings best suited to the kernel size must be established when brewing with Canadian malts, as they may be different from settings used for malts of different origin. The precise mill settings can only be determined through trial and error, but some varieties with very plump kernels will require slightly larger roll gap settings. Mills that are set too tight will give higher yields, but runoff may be unacceptably long. Conversely, gaps that are too large will give fast runoffs but poor yields. The settings for four-roll mills, or wet mills, will of course be different.
Mashing
A specific weight of crushed malt is added to the mash-mixing vessel that contains an appropriate amount of water. In a typical mashing cycle, the initial water temperature of about 45oC is held for about 20 minutes before being gradually increased in a series of "steps". These temperature "rests" allow for malt enzymes to take the sequential action required to produce sweet wort from the malt and adjunct components of the mash. In the "double mash" system common in Canada, the optimum temperature for mash scarification (approximately 65oC) is achieved by adding adjunct mash at boiling to the main mash.
Wort separation
After mashing, the entire mash is transferred by gravity or pump to either a lauter tun or (less commonly) a mash filter where the liquid wort is separated from the mash solids. Lauter tuns are circular vessels with slotted floor plates, providing a large surface area for wort filtration. The barley husks from the malt settle onto the floor plates, providing a filter medium through which the wort is drawn. The residual mash is then sparged (raked and sprayed with hot water) to recover as much extract as possible.
Mash filters consist of polypropylene cloths through which the liquid wort is separated from the mash solids using high pressure. A combination of sparging and compression of the mash plates ensures maximum recovery of wort. Using mash filters, wort separation can be achieved in less than an hour, while lautering typically takes up to two hours to complete.
Wort boiling
After lautering, or mash filtering, the wort is boiled for at least an hour in the presence of hops. Evaporation rates of seven percent per hour are common with vigorous boils. The objectives of boiling are to:
- sterilize the wort
- inactivate all enzymes
- concentrate the wort to the desired specific gravity
- extract desirable hop bitterness and aroma
- coagulate some of the wort protein to improve beer stability
Boiling also increases the colour of the wort due to biochemical reactions similar to those which occur in malt kilning. The specific gravity of the wort indicates how much sugar is present, from which the amount of alcohol that will be formed by fermentation can be calculated. The residual hop material, coagulated proteins and tannins (collectively called trub), are removed as "hot break" in a vessel known as a whirlpool.
Fermentation
Using a plate heat exchanger, the hopped wort is cooled to between 8 and 15oC before fermentation. Heat drawn from the wort is used to heat incoming brewing water for subsequent mashes. Oxygen is usually injected into the cooled wort to ensure sufficient oxygen is available for yeast metabolism in the early stages of fermentation. Yeast may be added to the cooled wort en route to the fermentation vessel, or "pitched" directly into the fermenter as it exits the cooler.
The strain of yeast chosen, wort composition and conditions of fermentation all have a profound effect on the type and quality of beer produced. Lagers are generally produced by slow, cool fermentations (8 to 15oC), at the end of which the yeast settles to the bottom of the fermentation vessel, to be collected for repitching. Ale characteristics come from warmer (15 to 20oC) and more vigorous fermentations. Ale yeast rises to the top of the vessel at the end of fermentation, where it is "skimmed" for use in subsequent brews.
Fermentation, usually in closed vessels, proceeds for about seven days, during which time fermentable sugars are converted to alcohol and carbon dioxide. The spectrum of fermentable sugars and nitrogenous compounds in the wort not only influences the rate and degree of fermentation, but also the levels of yeast metabolism by-products, which contribute to beer flavour and character.
Maturation, filtration and stabilization
From the fermenter, beer is transferred to large tanks where it matures for a period of 10 to 21 days at -1oC. During maturation, residual yeast settles out, and further complexing of proteins and polyphenols may occur, forming hazes, which are subsequently removed by filtration. In addition to filtration through diatomaceous earth, beer may be further stabilized by either pasteurization or sterile filtration prior to final packaging. As oxidation leads to staling and other undesirable flavour changes affecting the shelf life of beer, care must be taken to avoid uptake of oxygen throughout the brewing process, and particularly during packaging.
What Does the Brewer Need in Malt?
Luckily the attributes of Canadian malting barley match the requirements of the brewers. Because of assured varietal purity, malt produced from Canadian barley has more consistent kernel size than Australian or European barleys, which translates to more consistent milling and control. Canadian barley produces well modified malt that has a high diastatic power and alpha-amylase (i.e. a high enzyme package), possesses low beta-glucan and has a high extract. Fortunately, Canadian malts have enzyme levels that are up to the challenge, and brewing with high adjunct ratios is not a problem. The trend to beers with higher adjunct ratios has generated a need for malt with a higher enzyme content, as up to 50% of the raw material may be rice or corn. The high enzyme potential of Canadian barley and the resulting high degree of malt modification means that less time may be required for proteolytic rests and conversion for Canadian malts than for malts from other countries. This results in greater brewhouse productivity by reducing the brew cycle timing (i.e. less time required in the mash tun which is usually one of the bottleneck for timing in the brewhouse). Typically a savings of 20 minutes of conversion in the mash tun can add up to an additional 7 to 10 brews per week through the brewhouse). Also, the increased availability of Diastatic enzymes (especially ß-amylase) permits precise control of mashing to yield worts that contain the desired range of fermentable sugars required for production of particular beers (i.e. more beer styles can be produced).
The relatively higher extracts of malt produced from Canadian barley is also an advantage in the brewhouse in that less malt is required, resulting in cost savings over other barleys. As Canadian malts tend to have slightly higher levels of soluble protein, they produce highly fermentable worts even at the highest adjunct levels. As well, the higher protein in Canadian barley results in the high levels of free amino nitrogen (FAN), which provide the yeast with enough nutrients to ferment worts with high adjunct levels and higher original gravity, up to 18 deg. Plato. The higher levels of protein and FAN can prevent the sluggish fermentations that often occur when the adjunct ratio is raised. There is enough soluble protein to promote healthy yeast growth, but not too much to affect the physical stability of the beer (i.e. haze). Because of the higher level of FAN there is no need to add artificial yeast foods such as Zinc Sulphate to worts to promote acceptable yeast growth. The wort produced should be clear, and the beer should filter well in the lauter tun and also as mature beer.
Beta-glucans are an important group of compounds present in malt, and high levels can cause processing problems, as they will significantly increase the viscosity of the wort. Canadian barley varieties have always produced malts with relatively low beta-glucan content, much lower than barleys from Europe and Australia. High levels of beta-glucan in the fermented beer can cause filtration problems, but this is not a problem with Canadian malt, due to its inherent low level of beta-glucan. The lower levels of beta-glucan allow brewers using malt from Canadian barley to runoff wort from the lauter tun more quickly, usually within 120 minutes or less. This again is a benefit in reducing the brew cycle timings, allowing for more production out of a brewhouse in less overall time. In beer filtration the lower levels of beta-glucan allow the brewer to have longer filter runs (more economical) and use less filter powder (cost savings). In terms of quality, the fewer times that you have to shutdown a filter run and start a new one, the better since there is a possibility of oxygen pickup at start-up. Additionally, with each filter start-up there is a loss of beer, adding to the total cost of the business. Brewing customers of Canadian barley also are interested in the lower colours generated, because this allows the brewer to have a wider range of options from a lighter base. Finally, brewers note that the use of malt from Canadian barley produces beers that have a better flavour, described as more mellow and less harsh.
When well modified, the new varieties AC Metcalfe, CDC Kendall, and CDC Stratus have lower wort beta-glucan than Harrington. Breweries in Canada using the new varieties have reported faster runoffs. The malt should have a low DMSP, the precursor for dimethyl sulphide in final beer. Finally, the malt should be adaptable to a number of beer and brewing styles and exhibit the right flavour profile. Malt produced from Canadian barley varieties produce highly fermentable worts, allowing the modern brewer to precisely adjust both mashing and fermentation conditions to achieve desired beer styles. Thus, the same malt source can be used to produce a range of beers, such as Pilsner, dry and light beers, which differ in degree of fermentation, level of residual sugar and alcohol content.
Since the "discovery" in the late 1970’s of DMS and its precursor DMSP, and their effect on beer flavour, Canadian maltsters and brewers have led the way in understanding and controlling DMS and DMSP in malt and beer. Today most brewers have specifications for these compounds in their malt, as well as in the finished product. As a result, Canadian malt has very low levels of these compounds. There was a time when a 90 to 120 minute boil was necessary to ensure low levels (<50 ppb) of DMS in the finished product, but with current levels in Canadian malt, a 60-minute boil is sufficient. However, care must be taken not to hold the wort in the whirlpool too long as the residual DMSP will continue to produce DMS.
Canadian 2-Row Malts
Harrington, the standard for Canadian malt since the 80’s, possessed all of the necessary attributes to be the long standing favourite of the farmer, the maltster and the brewer. Harrington is now aging as a genotype and has fallen out of favour with the farmer and now with the maltster and brewer. In the farmer’s world, Harrington has a lower yield than that of the new malting and feed varieties, it is susceptible to disease and loses vitality over time. These are all classic signs of an ageing genotype. In the maltster and brewers eyes it suffers from marginal hull adherence, and so does not mill as well as the newer Canadian varieties, which have improved hull adherence. Additionally, the new varieties have higher extract, better enzyme packages and lower beta-glucan than Harrington.
The new varieties of 2-row malt includes AC Metcalfe, a cross of Manley and Oxbow, which received full registration in 1997; Stein (cross of Norbert and Hector/Klages), registered in 1992; CDC Stratus (cross of Manley and Bancroft) registered in 1999; CDC Kendall (Manley crossed with SM85221) registered in 1999; and Merit (Manley cross with S74234 and Summit) registered in 1999. A comparison of the malting quality of each of these new varieties compared to Harrington is contained in Table 1. All of these new varieties give better yield for the farmer and have a higher disease resistance, which translates into money in the farmers’ pocket. For the maltster and the brewer the new varieties show increased enzyme packages over Harrington, reduced beta-glucan, similar extract and slightly lower soluble protein. Hull adherence of these varieties is better than in Harrington. Once again these factors end up allowing the maltster and the brewer to be more cost effective.
Table 1. Comparison of New 2-Row Varieties to Harrington
 | Harrington | AC Metcalfe | CDC Stratus | Merit | CDC Kendall |
| Moisture, % | 3.5 - 4.5 | 3.5 - 4.5 | 3.5 - 4.5 | 3.5 - 4.5 | 3.5 - 4.5 |
| Fine extract, % | >/= 80.5 | >/= 81.5 | >/= 80.0 | >/= 81.5 | >/= 80.5 |
| Color, EBC | 3.0 - 4.0 | 3.0 - 4.0 | 3.0 - 4.0 | - | 3.0 - 4.0 |
| Total Protein, % | </= 12.5 | </= 12.5 | </= 12.5 | </= 12.0 | </= 12.5 |
| Soluble protein, % | 4.7 - 5.3 | 4.7 - 5.3 | 4.6 - 5.0 | 4.8 - 5.2 | 4.7 - 5.1 |
| Kolbach index | 43-47 | 44-48 | 38-42 | 46-48 | 38-42 |
| Diastatic power, L | 110-130 | 100-120 | 110-130 | 115-135 | 120-140 |
| Wort B-Glucan, ppm | 100-130 | 70-100 | 120-150 | 70-90 | 70-100 |
On the horizon is a new batch of 2-row varieties including CDC Copeland, CDC Select, AC Bountiful, Calder and Newdale. These varieties are improvements again over the current barleys and should start to commercial quantities within the next couple of years.
Canadian 6-Row Malts
The 6-row varieties have seen a greater turnover than the 2-row because no one variety has proven itself as superior in quality as Harrington did. As a result, new barley varieties have been rolling through the system more regularly. BT1602, registered in 1991 (cross between 6B78-628 and Morex) is the oldest cultivar amongst the group and was the first white aleurone 6-row to be widely accepted. Until 1991, the 6-row barleys were blue aleurone to prevent cross contamination of the malting barley with the white aleurone feed varieties. In 1998, two new varieties were registered, Excel (cross of Robust, Cree, Bonanza and Manker) and Robust (cross of Morex and Manker), both whites. In 1999 CDC Sisler was registered (cross of Argyle/M34). It is a sister to the blue Tankard variety. Overall these varieties are less plump than 2-row malts and contain less extract, although that is changing as new genotypes are developed. The enzyme package is extremely high, allowing for routine brewing with up to 50% adjunct and original gravities up to 20 Plato. Overall the soluble protein is similar to that of the 2-row barleys. Typical analysis is shown in Table 2. The upcoming 6-row barleys include CDC Yorkton, CDC Battleford, CDC Tisdale and Lacey.
Table 2. Comparison of 6-Row Varieties
| Excel | Robust | B1602 | CDC Sisler |
| Moisture, % | 3.5 - 4.5 | 3.5 - 4.5 | 3.5 - 4.5 | 3.5 - 4.5 |
| Fine extract, % | 80.1 | 79.8 | 79.0 | 79.8 |
| Color, EBC | 3.0-4.0 | 3.0 - 4.0 | 3.0 - 4.0 | 3.0 - 4.0 |
| Total Protein, % | 11.0 | 11.8 | 11.6 | 11.4 |
| Soluble protein, % | 5.2 | 5.3 | 5.0 | 5.3 |
| Kolbach index | 47 | 44 | 43 | 46 |
| Diastatic power, L | 145 | 158 | 154 | 164 |
| Wort B-Glucan, ppm | 104 | 105 | 83 | 75 |
Conclusion
Brewing with Canadian malt offers great flexibility to the brewer in terms of designing the brewing process to optimize brewhouse yield without compromising performance, at the same time ensuring the highest level of beer quality. The major change required upon changing to newer varieties is to make adjustments to the mill to allow for changes in the barley sizing. Conversion time will be adjusted, probably to require less time, thereby shortening the brewing process making the brewing more economical. Similarly reduced beta-glucan levels will reduce lautering and filtration times. The increased extract will allow the brewer to reduce the amount of malt required to brew a recipe using the older barleys, again reducing costs.
Any variety of Canadian malt will make any beer style. T here are subtle differences that may appeal to different brewers and may provide opportunities for different recipes and may be more suitable for different beers. Because of the low colour, brewers can brew a light Pilsner style beer to, with the addition of dark specialty malts, a dark stout. Merit and Stratus would be suitable malts to use for this purpose. The flavour imparted to beer by Canadian barley has been described as mellow and less harsh than other barley varieties, so this aids the brewer in duplicating many styles. The higher enzyme package of the Canadian malts aids in the production of higher adjunct beers, and could be used successfully for the new Japanese low malt beers (Happo-shu). The higher enzyme package can also be useful in the production of "Dry" beers, those beers in which the starches have been converted over almost 100% to fermentable carbohydrates, so that the final beer is devoid of sugars. CDC Kendall would be the ideal candidate for the high adjunct and Dry beers owing to the extremely high enzyme package. The higher FAN content of malt from Canadian barley enables the brewer to produce beer free of fermentation additives, which down the line could enable the brewer to produce an additive-free beer, or an organic labeled beer. The high FAN content could also be used to overcome naturally sluggish fermentation due to the yeast strain employed by a brewery, or the fermentation vessel architecture (horizontal versus vertical, multi-brew versus single). In conclusion, malt produced from Canadian barley is well suited to the process of any maltster or brewer in the world. In both industries there are cost savings possible and the promise of improved quality.
Robert McCaig
Canadian Malting Barley Technical Centre, Winnipeg, Manitoba
Presented at the 3rd Canadian Barley Symposium, June 19-20, 2003 |
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