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Slow cooker as a water jacket

slow-cooker double boiler

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Water in the crock with a smaller stainless pot or heat-safe jar supported inside it, so the food never touches the hot ceramic and can be lifted out to stop heating.

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Illustration of Slow cooker as a water jacket.

Overview

The crock becomes a double boiler. The water spreads heat around the inner pot and buffers the hot wall, and the pot can be lifted out in one move.

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How it works

Food in a water bath cannot exceed the water temperature, and it approaches that temperature more slowly as the gap closes. The bath must run above the food's target, and the food must be lifted out when it arrives.

The extra water adds thermal mass. Heating is slower, but stored heat stays behind when the pot is lifted.

Precedents: Jim Wallace's Cheddar recipe calls a water bath in the sink the most stable way to warm milk. O'Connor's scamorza heats milk indirectly. Wallace's mascarpone uses a bowl over 2 to 3 inches of water. Tony Hamblyn's brewery uses the same principle at scale.

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Documented and proposed uses

Mascarpone: replaces the pot of simmering water under the bowl; the bath must run above 185 to 190 °F.

Quark: initial warm-up to 86 °F, then the pot is lifted out to cool.

Ayib: holds buttermilk at a measured temperature.

Clotted cream: an open shallow dish warmed from below. Its surface behaviour is untested.

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Measuring

Run a water-only trial first, with the intended volumes: both temperatures against time on High, after switching off and after lifting the pot. Then measure the food temperature in a real batch.

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Limits

This set-up is untested on any slow cooker. Whether a crock of water can bring an inner pot of milk to 85 to 90 °C is unknown, so paneer is a poor fit.

It is slower than direct heating. A float-free, stable support is required. A brewing false bottom or an improvised stand is not a rated support (reasoned).

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History

The water-bath principle is documented in cheesemaking recipes and in a New Zealand brewery's scale version. The slow-cooker use is an adaptation, and no source tests it.

Site

SettingA kitchen counter: a slow cooker's stoneware crock holds water, and a smaller stainless pot or heat-safe jar stands inside it.
ClimateWater at the temperature the food needs, held by the slow cooker's base on its settings.
NotesNo source gives a slow cooker's dimensions or the volumes this set-up needs.

A build is made where it stands: moving it means building it again.

How it is built

Risks and precautions · Standard risk
Stoneware cracking from sudden temperature change

The booklet says stoneware will not withstand sudden temperature changes.

Hazard source

Put water in the removable stoneware, never in the base, and keep the base out of the water.

Control source

Keep the water within the manufacturer's fill range. Do not let the inner pot float, tip or rise.

Materials

  • 1 Slow cooker with a removable stoneware crock — Water goes in the removable stoneware, within the manufacturer's fill range. The base is never immersed.
  • 1 Smaller stainless pot or heat-safe jar — Stands on a rack, or hangs by its rim so it cannot float. Its rim stays above the water.
  • 1 Rack or rim support — Keeps the inner pot steady, so it cannot float, tip when stirred or rise as whey is removed.
  • 2 Two probes — One in the food and one in the water.
  1. Put water in the stoneware crock, within the fill range.
  2. Stand the smaller pot or heat-safe jar on a rack, or hang it by its rim, so it cannot float or tip.
  3. Check that the rim stays above the water while the water reaches the pot's sides and base.
  4. Run a water-only trial with the intended volumes: both temperatures against time on High, after switching off and after lifting the pot.
  5. Then run the food batch, and lift the pot out to stop the heating.

Places

Documented for international use, with no single place of origin assigned.

Related

Used for

  • Clotted cream (Cornish style)

    High-fat cream scalded below boiling for at least an hour until a thick crust forms, then cooled hard so the crust sets and the cream beneath thickens.

  • Mascarpone

    A rich fresh cheese made by heating milk and cream in a double boiler and setting them with tartaric acid, or by culturing them with a crème fraîche culture.

  • Quark

    Quark is a soft, fresh curd cheese used in spreads and desserts. This small home batch sets milk with mesophilic culture and rennet before refrigerated drainage.

Read more

  • A slow cooker as a small dairy

    A slow cooker can heat milk for mozzarella, paneer, ricotta, mascarpone, quark and yogurt, but its heavy crock keeps heating after it is switched off. This is what each fresh cheese needs from it.

Modern era

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    Soft, spreadable Calabrian pork sausage made with a great deal of red chilli and fatty pork, stuffed into natural casings, sometimes smoked and matured while staying soft.

  • A measured dehydrator retrofit

    A way to add independent temperature logging to an existing food dehydrator without changing its built-in controls or protections. It is a monitoring method, not a rewiring plan.

  • Abalone mushroom

    Pleurotus cystidiosus is the abalone mushroom, a cultivated oyster-type fungus with dark brown caps that grows more slowly and is more demanding than other Pleurotus species.

  • Aceto Balsamico di Modena IGP

    A dark, balanced vinegar from Emilia-Romagna made by combining cooked or concentrated grape must with wine vinegar, then acetifying and refining it in wood under a protected specification.

  • Active sour-cream starter

    A living dairy inoculum that starts controlled cream fermentation, developing acidity and aroma before sour cream or cultured butter is finished.

  • Adjustable yogurt-maker

    A small electric incubator holds jars at a selected temperature for yogurt and other documented warm food preparations. Controls, capacity and vessel arrangement vary by model.

  • Adygean salt

    Adygean salt is a seasoned table salt associated with Adygea and the wider North Caucasian culinary tradition. Salt is blended with garlic and a variable selection of herbs and spices; the exact mix depends on the named style and maker.

  • African Caesar-group mushroom

    The African Caesar-group mushroom, Amanita masasiensis, is a wild ectomycorrhizal species of central and southern African woodlands, eaten locally. The genus contains deadly poisonous species, so identification needs care.

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