Ferment

Diligently following on from the end of yesterday's journal, I couldn't smell apricots. Maybe it needs to be warmer

Walking through the village, the afternoon calm was fragmented by enormous farm vehicles - tractors with four wheels that are wider in diameter than my height - towing trailers of correspondingly giant proportions. I had a bizarre, momentary sensation that I had sipped a 'drink me' potion

The last time these behemoths were passing back and forth, the perfume in their wake was less than pleasant - cow slurry, from the large dairy farm in the edge of the village. The cattle never go out to graze, spending their lives in a barn with food brought to them and waste taken away, so no surprise they need big tractors

I braced myself, but was pleasantly surprised that today's transit was on the way in, not out: not slurry, but silage. Silage is one of my favourite farm smells - that thing of smells being a fast-track to memory again, an instant transit back to frosty Saturday mornings with a much smaller trailer and a hand fork - different technology, but no change of smell.

Silage is just fermented grass. With the right bacteria present, as little oxygen as possible - so compressed and sealed in plastic - and young grass with plenty of sugar in the sap, the sugars are fermented by the bacteria to lactic acid, which builds up to such concentrations that the grass is pickled and preserved - a tasty winter sauerkraut, as far as livestock are concerned. The lactic acid is a major component of the pleasing smell.

It can go wrong. The wrong kind of bacteria can get in if the grass is contaminated with soil or the process is not kept airtight. The fermentation can then create butyric acid, rather than lactic, which smells much less pleasant, as any cow would tell you. They don't like eating it and they don't digest it well

Only when I topped up the sourdough starter this evening did it dawn on me how much the smells have in common. I knew the mix of fungi and bacteria in sourdough includes lacobacilli, but I had not quite made the connection that the smell of lactic acid is the reason I love sniffing the starter so much

I tried and failed to get a picture of the giants. Not only are they big, they are fast! The old, original, 1850 brewery building sat obligingly still. Fermentation does not happen here any more - the upper floor is a museum and the ground floor a visitor centre & shop, where fermentation products are available (and pickles)

I love the thought of the meeting where the design for this wall was presented to the client. "We will have a mix of dressed local stone with bricks; some of the bricks will be red and some blue and we will alternate them; some will be laid flush with the wall and some will be on the diagonal; the upper windows will have straight wooden lintels, the lower ones will have arched lintels constructed with the alternating bricks laid radially to the arch; the buttresses at each end of the arched brick lintels will be stones dressed to the correct angle; the upper windows will be wooden, the lower ones cast iron, painted blood red; the sides of the lower windows will also be edged in brick, alternate courses being laid end on and side on but with tie-bricks in the positions specified in the diagram... Don't look so worried, it will be fine!"