Malting and Brewing Basics
Malt is made from premium quality barley and provides the characteristic flavours, aromas and colour that beer drinkers are familiar with and also contributes to the whole brewing process (along with water, hops and yeast).
Malting involves the germination of barley until the food store within the barley corn (the endosperm) has undergone a certain level of degradation by the action of enzymes. The maltster is therefore concerned with:
(i) a significant breakdown in the cell wall material surrounding the starch granules
(ii) the partial degradation of the starch
(iii) the accumulation of an adequate complement of enzymes in the barley which are available to the brewer later in the brewing proces to complete the starch breakdown.
In order that the maltster can store the germinated barley in a stable condition, the the germination process is terminated by drying the grain in a kiln.
In choosing a parcel of barley required to achieve these requirements, the variety of barley chosen is a key requirement. The variety and parcel of barley chosen must be able to:
(i) Achieve rapid and uniform germination of the individual barley grains in the sample
(ii) Achieve even enzymic degradation of the endosperm
(iii) Achieve an adequate complement of enzymes, even after kilning (which is highly detrimental to enzyme survival)
(iv) Achieve as high as possible a liquid extract rich with soluble breakdown products of the malted grain.
The brewing of beer from malted barley ( and potentially from other malted grains) involves:
(i) Milling or grinding the malted barley into a coarse "flour-like" medium
(ii) Mashing with water the milled malted barley to extract a liquid rich in starch in solution
(iii) Boiling this extracted liquid with hops (for flavour)
(iii) Cooling the extract and fermenting it with the addition of yeast
(iv) Clarrifying the fermented beverage and packaging it in an effervescent condition.
There are many styles of beer (newly created styles and brews from recipes dating back hundreds of years) which use markedly different techniques of brewing, and importantly, different quality characteristics of the underlying main ingredient – malt made from barley.
In the markets where Australian malt and barley is sold, these quality characteristics are in two main categories – those characteristics required for starch adjunct brewing and those required for sugar adjunct brewing.
In most Asian style beers, a solid form of starch like rice, sorghum or corn is added during the brewing process as an “adjunct” in addition to the malt. This adjunct provides additional sugars to make the beer, and as such this important export market is often referred to as the “starch adjunct” market.
This “starch adjunct” market requires barley processing quality parameters such as diastatic power, (a measure of the enzyme activity contained in the malted barley that break down sugars) to be at a high level.
These enzymes present in the malted barley need to be at a high level to be able to act on not only the remaining starches existing inside the barley kernel, but also the starch provided in the adjunct (raw rice, for example) to be able to convert it to sugar. It is this converted sugar to which yeast is then added and can then ferment into alcohol in the brewing process.
Alternatively, in the Australian marketplace beer is brewed with the addition of an actual sugar which is usually provided in a liquid syrup form. Hence this market is termed a ”sugar adjunct” market as the added sugar is literally an adjunct to the brew.
The enzymes at work in the brewing process here (represented by the levels of diastatic power) are not required to modify any starches in the added syrup into sugars as it is already in accessible form to the yeast to feed off in the fermentation process.
In other words the malt needs to work ‘harder’ in a brew containing starch adjuncts (like in the export market), than in an Australian style brew that includes these easily accessible sugars in liquid syrup form, or “sugar adjunct” that are already available for the yeast to feed on.
Other quality parameters required in barley and malt will also differ depending on the malting and brewing processes and beer types that each customer or market is making.
The Australian barley industry has raised the bar on new varieties designed for the “starch adjunct” market developed and released over the past 5 years; in fact the quality of Australian malting barleys is now considered the best in the world by international customers.
The efforts of Australia’s barley breeders have now delivered several new varieties - lifting the bar on critical parameters like diastatic power, fermentability and yield. It has helped to increase Australia’s market share and improve productivity for our brewing customers in Asia; the ultimate outcome delivering a better quality, better performing malt to the customer.
Matching the inherent quality parameters of a malting barley variety to a specific end market is imperative: the Australian marketplace is listening to our customer requirements and effectively passing this message back to our breeding programs.