Three Warm Corners and a Pint of Milk: Testing Yoghurt Set-Ups in a Rented Flat
November is the month the heating clicks on in bursts and every rented flat reveals its own microclimates. The radiator by the desk is too hot to lean on, the bathroom is permanently cold, and the top of the fridge is oddly balmy. Which is exactly why the Warm Shelf Yoghurt Club started: a pint of milk, a £1 thermometer and a Kilner jar, moved between three possible warm corners like a very low-stakes science experiment.
This is not a yoghurt-maker review. It is a flatshare project for people who want a thick tub in the fridge without buying another single-use appliance. It also answers the practical question: if you do not have an airing cupboard, where on earth do you put the jar?
The kit, kept deliberately small
You need a pint of supermarket whole milk (568ml), two tablespoons of live plain yoghurt to start, a saucepan, a whisk, a 500ml Kilner jar and a thermometer. The thermometer is the one bit of kit worth buying rather than guessing. A basic dial or digital probe can be found for around £1 in a kitchen shop or market hardware stall; a digital one is faster but not essential. Sterilise the jar with boiling water and let it dry.
The starter can be any live yoghurt from the supermarket. Keep a couple of spoonfuls back from each batch and you will not need to buy another starter for weeks, as long as you are making a new batch every week or so.
The method, stripped back
Heat the milk to 85°C — just below a simmer. This changes the milk proteins so the yoghurt sets thick rather than sloshing about. Let it cool to 43°C. If you do not have a thermometer, a clean finger held in the milk should feel comfortably warm, not hot, but a thermometer removes the guesswork.
Whisk the starter yoghurt with a little of the warm milk in a jug, then stir it back into the pan. Pour into the jar, screw the lid on, and put it in your chosen warm spot. Leave it for 8 to 12 hours, then refrigerate. It will firm up further once cold. For a thicker set, strain through muslin or a clean tea towel for an hour or two after chilling.
Three warm spots, one week
The top of the fridge
Temperature: roughly 22–25°C. This was the slowest spot. After 12 hours the yoghurt had set but was soft, more like a pourable set yoghurt than a thick one. It tasted clean and mild. If your fridge has a warm back panel or sits in a small kitchen, this is a decent overnight option, but you will need to strain it for anything spoonable.
The boiler cupboard shelf
Temperature: around 28–30°C. This was the winner. Eight hours produced a thick, mildly tangy yoghurt with a clean break when the jar was tilted. The cupboard is not an airing cupboard — it is a small built-in cupboard next to the combi boiler in the hallway — but it holds a steady warmth. A tea towel on the shelf stops the jar rattling when the boiler fires up.
The oven with the light on
Temperature: 30–35°C, and less stable than it sounds. Six hours gave a very fast set, but the edges were grainy and the whey had begun to separate. It is workable if you check at five hours and move the jar to the fridge as soon as it is set, but it is the least forgiving option. Do not use the oven for anything else while the jar is in there, and do not turn on the grill to “hurry it along”.
What it actually costs
A pint of own-brand whole milk costs around £1.15 in a London supermarket. That makes roughly 500g of yoghurt once the whey is drained off, plus a cup or so of whey. A 500g tub of own-brand live yoghurt sits around £1.80–£2.60 depending on the shop and the brand. So the saving is roughly 65p to £1.45 per tub, and more if you buy the bigger tubs of starter once a month rather than weekly.
The Kilner jar is a one-off cost if you do not already have one. The warm spot uses heat you are already paying for. This is not a project that will pay off a mortgage, but it is a satisfying way to turn a cheap pint into something that feels like proper kitchen work.
When it goes wrong
Runny set: the milk was too cool, or the jar was left for too short a time. Move it somewhere warmer and give it another four hours, or strain it and call it drinking yoghurt.
Grainy texture: the milk was too hot when the starter went in, or the jar was jolted during setting. Blend it smooth or use it in cooking — graininess is a texture problem, not a safety problem.
Very sour: you left it too long or used too much starter. Use less starter next time and check at eight hours.
Separated into curds and whey: the warm spot was too hot. Strain the curds through muslin, salt lightly, and you have a soft cheese for toast. The whey goes into soup.
Pink or fuzzy mould: bin the whole batch and start again. Do not scrape it off and hope.
The whey problem
A pint of milk makes more whey than you might expect, and pouring it down the sink feels wrong. It is slightly acidic, mildly salty and full of protein. Keep it in a jar in the fridge for up to five days, or freeze it in an ice cube tray.
Use it in split pea or leek soup instead of some of the stock. Replace the water in flatbread dough with whey for a softer crumb. Soak porridge oats in it overnight before cooking. Use it as the liquid for a quick brine for chicken thighs or sliced sprouts. Or stir a splash into a pan of onions that are threatening to catch.
A flatshare protocol
If there are three of you and one warm cupboard, agree a rota. One batch each per week, labelled with the date and the maker’s initials, and nobody moves the jar while it is setting. The boiler cupboard is communal space, so keep the jar on a small tray with a tea towel and do not leave it there for days on end.
The Warm Shelf Yoghurt Club is not really about saving money. It is about learning the warm corners of a rented flat well enough to make something useful in them. November is a good time to start: the heating is on, the boiler cupboard is doing its quiet thing, and a jar of milk on a shelf is a small, steady project in a month that can feel short on daylight.
