Goat’s cheese with squash and pickled peppers flatbread

interface of air and liquid meet, mostly being aerobic/microaerophilic (requiring some oxygen to survive). Kahm is not often considered to be dangerous; people usually scrape it off – unless it’s in large quantities, when it can make a ferment taste cheesy or like old socks.

“Kahm grows more readily when temperatures are higher than room temperature, or when the salt concentration isn’t high enough. People often use a 2 per cent brine solution, but there’s a reason why that isn’t often enough – if you have many peppers and not much brine, for example. A better rule of thumb is to add

2 per cent salt for the total weight of peppers and water in the jar, thus having 2 per cent brine for everything in the jar. It is possible that kahm has grown in little air pockets caused by the peppers being squeezed against the

sides of the jar; but it doesn’t seem to be present on the top, which one might expect.

“From the photograph you sent [pictured left], I can’t see if your peppers are protected on the top – it’s good practice to put a barrier in place (a foodsafe plastic disc, a cabbage leaf or a ziplock bag filled with brine) to keep them submerged, which can prevent kahm or mould from growing. At the bottom of the jar, you might find a layer of white sediment. I suspect this is normal sediment being prevented from falling to the bottom by the proximity of peppers to the sides. Any fermented food maker has to make the final call – so I can’t tell you to eat it, but unless it’s slimy or smells unpleasant, I’d certainly be tempted to carry on!” Email your culinary conundrums to askxanthe@telegraph.co.uk