Students often ask me about malt. The home baker and anybody interested in the world of bread is aware of malt products, seeing flours at the supermarket that have added malt, enjoying the maltiness of granary type loaves, noticing recipes that call for barley malt syrup. Most people agree that malt is an attractive flavour. However, not many students will have much of a grasp of the complicated field that is malt. After all, just like the crafts of milling and baking, there is also the craft of malting.
As background it is important to consider what is happening in the fermentation process. “Fermentation” involves the breakdown of sugars by micro-organisms, typically yeasts and bacteria, causing the production of carbon di-oxide gas and ethyl alcohol as these micro-organisms consume the moist host that provided the sugar. In our bread making fermentation the yeast that we bakers use, brewer’s yeast, needs to be supplied with the class of sugar called maltose, which its own enzymes in turn break it down to glucose – the sugar it likes to absorb. Maltose does not exist as such in the grain, but is created when the enzymes that belong in the grain convert the starch to sugars, mainly the maltose type.
Another critical background area is what happens in nature: these enzymes are placed there to convert the grain’s starch into sugar to feed the germ when the seed sees fit to germinate. Germination is automatically triggered when suitable ground moisture and temperature levels prevail. In our artificial world of bread making, in the moist medium of dough we utilise the same enzymes to break down the damaged flour starches (damaged by the abrasive impact of milling) to provide the maltose to feed the yeast that we implant into the dough.
The producer of malt, a craftsman called the maltster, is working with barley to provide malt for his main customers – brewers. On the floor of the malting room the maltster will artificially germinate the barley which, moist from pre-soaking, is set down at a particular temperature(usually about 18°C) to germinate. Inside the grains there is an upheaval as the two enzymes known as amylase attack the starch to produce the maltose, being the type of sugar required by the seed to perform its germination and grow the sprout, which happens relatively quickly – a matter of days. The raw barley grain has now been “malted“, and turned into malt, as a pre-treatment for the beer brewing industry.
If the malting process was left to carry on, not only would the growing embryo (germ) consume too much sugar but, running out of starchy material, the enzymes themselves would be depleted with nothing left but the sugar. Hence, to retain adequate amounts of the active enzyme, the maltster abruptly stops the process. There is a brisk drying off, followed by a steady kilning that kills the germination process, and curtails any more enzyme activity because enzymes need moisture to function.
Various malt products are produced, some made from grinding the malted grain, others made by vacuum boiling and rendering a syrup. Whether or not the malt is described as diastatic or non-diastatic ( diastase was the older name for the amylase enzymes) depends on how high the temperature was taken to in the kilning and syrup boiling stage.
Lower temperatures leave the enzymes relatively unharmed so that the particular malt can go on being used as an aid to fermentation, and will be described as diastatic. The non-diastatic types will have been taken to higher temperatures, with diastatic activity both exhausted and destroyed, amounting to a product rich in maltose (sugar) but with no fermenting capability.
A typical non-diastatic product is the barley malt syrup that can be easily bought in jars at a health food shop. It is a sweet syrup, rich in maltose that can be used directly as yeast food. It also delivers that malty flavour, and by raising sugar levels it ensures bright crust colour because the yeast will not have had time to eat all the sugars present, and plenty will be left to caramelise in the crust. The malt powders (also called malt flours) will be added to proprietary branded malty preparations like granary, and would be added by a miller if the grain was perceived to be low in amylase activity. Similarly, malt products can be used by the individual baker to enhance fermentation or boost flour known to be low in diastatic performance.
Righto, malty ones, that’s it. Next time you hear somebody talking about malting you can dive in there with all your bread knowledge, until you realise they are talking about their pet and the hair on the couch.