Brewing in its purest form uses just water, heat, and the natural ingredients of malt and hops to generate an impressive array of enjoyable products.
Depending on the recipe used, the flavour will depend on the yeast, the hops or the malt. Hops are well known for providing bittering and citrus or floral notes, and yeast provides a plethora of flavour-enhancing esters, but the flavours from malt are often forgotten and it is assumed it merely provides a sugar source for yeast to ferment, or to impart colour to the beer.
So, what is malt and how can brewers get much more from it by understanding more of its attributes?
Malting is a natural process which converts hard cereal grains into easily milled malt. Barley is usually the grain of choice for malting because it is bred specifically for the ability to be processed easily and while generating a cascade of natural enzymes. These are used in later processing to convert starch (flour) into sugar and proteins into amino acids—all of which are highly nutritious when used in brewing, distilling or food manufacturing.
The entire process is inherently natural, as it uses just fresh water and clean hot air to produce a unique range of colours and flavours that cannot be reproduced by any other means. It is therefore an ideal ingredient for introducing wholegrain claims into the ingredient declaration.
The malting process starts by immersing barley in water. If the grain was sown in the ground, it would use water to start growing and produce green shoots and a plant.
Barley makes its own enzymes to generate nutrients. In malting, this process is controlled such that the grain starts to grow but does not produce a green shoot.
A prime purpose of malting a grain is to release a portfolio of enzymes for use by the next processor in the chain. Inside the barley grain is a growing part (the embryo or germ) and a food source (the flour or endosperm). The flour is tightly packed and not easily ground (milled). During malting, the endosperm is softened by the natural enzymes produced, removing the hard cell walls that hold the starch together.
The grain is so efficient at producing enzymes that when it is milled and mixed with hot water—as in brewing—it has the capacity not only to turn all its own starch into sugar, but can also digest other starch sources such as rice or maize which are added to increase the potential alcohol generated during subsequent fermentation.
During the malting process, the cell walls which contain beta glucan are removed along with the small starch granules, leaving just the large starch granules behind.
Why is this important for brewing? Beta glucan levels that are too high can generate hazy beer; small starch granules gelatinise at a higher temperature than most brewers mash at and do not convert easily to sugar, hence making the wort too viscous or slow to run off.
Malt Varieties And Nutritional Value
Malt is a diverse product and available in different styles. Normal malt after kilning is termed white malt and is relatively low in colour. It can be further roasted to create a magnificent palette of colour and flavour variations for use in brewing and food production.
There are two options for generating this increased range of malts referred to as speciality malts. If malt is taken and roasted direct from the germination box (here called ‘green malt’), it produces sweet fruity and caramel flavours. If the white malt is further roasted, it tends to generate more burnt, roasted and bitter flavours and dark colours. The final product is dependent on the roasting temperature and the length of time the malt is roasted.
Malt is highly nutritious and can be used in many forms. For brewing, it is milled and mixed with hot water which enables the starch to be digested to sugars that subsequently are used by yeast to produce alcohol. The protein within the malt also creates amino acids that are key to flavour development and yeast nutrition.
During malting, levels of vitamin B9 (folate) can increase up to 4 mg/kg. Just 100 g of malt provides approximately 10 percent of the daily recommended intake for vitamin B12, 44 percent of both vitamins B1 (thiamine) and B6 (pyridoxine), 34 percent of vitamin B2 (riboflavin), 88 percent of niacin and 80 percent of vitamin E, and in excess of 100 percent of the vitamin B9 (folate) requirement.
As malt extract, it has a low glycaemic index of 42. It contains antioxidants which protect against disease at levels similar to those found in red wine.
Malt extract is also a key product to deliver the unique attributes of malt. In this process, which starts in exactly the same way as in a brewery, milled malt is mixed with hot water to digest the starch into a mixture of complex sugars and amino acids in a solution termed the wort, but the wort is then evaporated under controlled conditions to create a viscous extract.
This product can have a wide range of colours, flavours and enzyme levels depending on which malts are used in the recipe. In its simplest form, the extract can be used for brewing by dilution with hot water and the addition of yeast. It can also be used directly in the manufacture of many food products, especially those wishing to claim the presence of wholesome natural cereals.
What Makes A Good Malt?
Malt in this context does not refer to the colloquial use of the word to mean a good whisky, but rather to the raw material itself. For the barley breeder, the difference could be as simple as whether the barley is suitable for feed use or malting, based on broad brush measures such as hot water extract, disease resistance and good agronomy.
For maltsters, a good variety would be one which performed well over a wide range of nitrogen (protein) contents and was easy to germinate and kiln. To a brewer, often it is extract yield, colour potential, clarity and flavour that constitute a good malt.
An overarching thread in all these requirements is that the best variety will reduce risk for the whole supply chain. Ideally, the breeder needs a variety that lasts up to 10 years to recoup breeding investment costs.
Farmers need the certainty that a crop will grow well and be versatile in different seasonal weather conditions. Maltsters need varieties that can guarantee availability of good quality raw material free from disease and requiring the least processing utilities input. Brewers also need a secure supply of raw material and for the malt not to give rise to any negative processing or taint issues whilst providing good yeast nutrition and contributing to colour and/or flavour.
A traditional malt analysis can be subdivided into five key groups: starch conversion, carbohydrate conversion, carbohydrate extract, colour, enzyme potential. Physical attributes of barley and malt of course affect all of these, but are not regularly considered important when assessing malt quality. This can of course be dangerous.
Varieties that differ in grain size distribution each year will not necessarily mill the same. Quite often, problems with malt processing in breweries can be traced back to an unchanged mill setting.
In a year with grains that are wider in diameter (bold), extract yield can be dramatically diminished by the generation of dust where mill gap settings are set too small. In a year where size distribution is lower, grains may be only partly milled giving rise to poorly digestible pieces of endosperm and non-digested glucan leading to haze.
Mill adjustment is such an important aspect of brewing performance, yet it is often the source of many hazy beers or reduced brew length. Picking up the problem at the malt specification stage by early discussion in a new season with the maltster could avoid costly volume reduction and filtration time in the brewery.
Is There A Flavour Specification For Malt?
Brewers normally taste their beer and carry out a visual assessment of the product in process or when packaged. It is surprising that there is not greater application of this for the malt being used. Whilst some brewers will taste the wort to assess suitability, the overriding flavour is sweetness.
There is a better method that involves grinding the malt coarsely and mixing with water. This identifies a much wider range of flavours that can be used to positively choose a malt based on its flavour or reject it because it has undesirable characteristics for the beer being made.
In this way, flavours can be understood as sweet and beany from the lower colour lager malts, to the nutty, cereal ale malts, or the crystal malts which can be either sweet and fruity or burnt fruity, treacle, or slightly bitter.
Flavour becomes less varied as you move through chocolate and black products which are smokier, intensely bitter and more coffee-like.
Sustainability can be defined in many ways with different impacts throughout the malting and brewing supply chain, and across different supply chains. This puts pressure on farmers to juggle various approaches for all the crops grown on their farms that currently require certification to a specific named accreditation scheme.
This has led to the creation of a cross supply chain consortium, the Sustainable Agriculture Initiative (SAI) Platform with the expressed aim of prescribing one common definition of sustainability. It does not require farmers to sign up to yet another green sustainability scheme, but rather creates a single benchmark for certification schemes and proprietary codes, and removes the need for company-specific sustainable agriculture codes.
SAI principles define sustainability in terms of environment, social and economic measures, and assess quality control and ethics. One of the most important tools available to the farmer is a Farm Sustainability Assessment which provides a way to assess farmer sustainability and gives a basis for improvement plans.
Where farmers have an existing sustainability system which has been compared with the SAI criteria, it may already be deemed as meeting the criteria at either basic or advanced level. In this way, farmers with existing suitable sustainability programs do not have to make any changes to be compliant with the overarching SAI assessment.
A number of international brewers are now setting targets for the proportions of sustainably sourced barley used to make malt, using the Farm Sustainability Assessment as their benchmark to verify sustainable supply. In some cases, it is a condition of supply that maltsters have an externally vetted sustainability program even before contract discussions begin.
Malt is a unique wholesome product that enables the food and beverage industries to generate a unique palette of flavour, colour and texture which is highly nutritious as part of a balanced diet.
Brewers could use this enhanced knowledge of malt characteristics more widely to generate novel products to differentiate new brands in an increasingly competitive sector that demands choice.