Sedgeford’s Anglo-Saxon Malthouse

It has taken five years and it has been hard work, but we are now confident that in Trench 23 we are excavating the only known Anglo-Saxon malthouse.

The corpus of Mid Anglo-Saxon grain-dryers is growing, and one or two of these have been identified as malting kilns from the carbonised remains of germinated grain found in and around them. But the dryers – or kilns or ovens or whatever we choose to call them – usually sit in splendid isolation, with little or no evidence for associated structures and features. They represent heavy investment in industrial-scale plant, but we cannot see the rest of the infrastructure, so we can’t reconstruct the whole process involved.

Dryers were probably multi-purpose. They could be used for baking bread and also for parching grain for storage, transport, and/or milling. But something different and more complex was happening in places where large quantities of germinated grain turn up in the archaeo-environmental samples. Sedgeford is one of those places.

Malting and brewing go back thousands of years. The basis of malting is that germinating grain initially feeds off itself by converting stores of starch into sugar, up to the point where a sprout is produced which penetrates the soil and absorbs external nutrients to feed further growth.

The maltster’s job is to trigger, control, then terminate this natural process, thereby converting starch-rich grain into sugar-rich malt, the latter being, of course, the raw material of brewing, which is essentially the fermentation of malt. The trick is to arrest the germination process – by drying – without destroying the enzymes necessary for fermentation by scorching and thereby killing the grain.

Three basic processes are involved. First, after the grain has been threshed, winnowed, and cleaned, it has to be soaked in a cistern for a couple of days until its volume expands by about 50% by absorbing water. Second, it has to be transferred to a floor for ten days to two weeks, with occasional turning, to allow it to germinate. Third, it has to be dried gently over a kiln for a day or so to halt the germination process and preserve the sugar-rich malt.

All three processes require control over the environment. Temperature, moisture, light, and ventilation need to be regulated. The only practical way to do this is to establish all three facilities – cistern, floor, and kiln – inside a malthouse. This has the additional advantage that all stages of the process are in close proximity, saving labour and reducing loss.

Our discoveries in Trench 23 are now making much more sense. The evidence is this: we have at least one, possibly two cisterns; we have at least two, possibly three, possibly more kilns; we have at least three, possibly more clay floors; and we have the remains of an uncertain number of burnt-down timber structures – including, in places, whole sections of collapsed wattle-and-daub wall.

Clay-lined floor of cistern

Kiln 1 with clay floor

Evidence of burning layer (as seen below horizontal ranging rod) on western side of Trench 23

Our working hypothesis is now as follows. A set of features – cistern, floor, and kiln – would have been contained inside a timber malthouse. Periodically there were accidental fires – an occupational hazard throughout the history of malting – and these necessitated wholesale replacement. Thus we have not just one, but a sequence of malthouses, each with cistern, floor, and kiln.

The excavation is now at a critical stage, and we will be entering the new season with a much clearer idea of what we are looking for. My guess is that a lot of things are going to start falling into place in Trench 23 in 2018.