Cutting Tonkotsu Simmering to About 2–2.5 Hours: Key Points for Making the Tonkotsu Broth You Want, from Light to Rich, in a Pressure Stockpot

Conclusion: cook tonkotsu sealed at about 120°C to cut the time sharply and still choose the strength

The quickest way to lighten tonkotsu broth prep is to cook under pressure at about 120°C, instead of in an open stockpot that only reaches 100°C. Meiwa Seisakusho’s commercial pressure stockpot cuts a tonkotsu simmer that usually takes 8–12 hours to about 2–2.5 hours (in-house results), and the strength of the broth can be adjusted from light to rich by changing the bone mix, the pressurizing time and how the broth is drawn off.

Tonkotsu is one of the most enduringly popular ramen broths. Yet drawing out its powerful richness in a regular stockpot requires hours on a high flame, cracking bones beforehand and constant stirring of the bottom to prevent scorching, which weighs heavily on both gas costs and labor.

Why tonkotsu takes so long in a regular stockpot

Making a rich broth from pork bones means softening hard bones so that the marrow, collagen and fat inside dissolve into the broth.

At 100°C, bones take a long time to soften

In an open stockpot, the broth only reaches about 100°C. Thick, hard bones such as pork leg bones soften only gradually from the outside, so drawing out enough marrow and collagen takes a long simmer.

Constant stirring to prevent scorching

The thicker the broth gets, the more easily bone fragments and meat on the bottom scorch. In a regular stockpot, someone has to keep scraping the bottom with a wooden paddle, standing by the flame for the whole prep.

What changes when you cook tonkotsu in a pressure stockpot

Here is how cooking tonkotsu in a Meiwa Seisakusho pressure stockpot compares with a regular stockpot.

Cooking at about 120°C softens even pork leg bones enough to snap by hand

A pressure stockpot cooks broth at about 120°C by closing the lid and building pressure. Pork leg bones can go in whole without cutting, and by the time the broth is done they are soft enough to snap by hand. The bones break down finely, which also greatly reduces their volume when discarded.

A double structure prevents scorching, so no constant stirring

Inside the pressure stockpot is a double structure with a perforated inner pot (basket). Bones and meat never touch the heated bottom directly, so even thick broth does not scorch. Once the specified pressure is reached, you simply switch to low heat and hold it for the set time, leaving you free for other work.

Key points for adjusting tonkotsu from light to rich

Some worry that everything cooked in a pressure stockpot will turn thick, but the strength can still be adjusted. Three things are mainly used to adjust it.

1. The bone mix

For lighter tonkotsu, use mainly head bones and back bones; for rich tonkotsu, use mainly leg bones and add trotters or back fat. The parts and amounts you use change the character of the broth significantly.

2. Pressurizing time

The longer the broth is pressurized, the more marrow and collagen dissolve and the richer the broth becomes. In Meiwa Seisakusho’s tests, two-stage pressurizing produced broth of up to 12% Brix (concentration) or more (results in the company’s test environment). How long it takes to reach the strength you want depends on the type and amount of bones.

3. How the pressure is lowered and the broth drawn off

Meiwa Seisakusho’s pressure stockpot can draw off broth either as a clear broth or as an emulsified paitan by adjusting how the valve is opened and how pressure is released. For a lighter finish, lower the pressure gently after heating rather than releasing it suddenly; for a rich finish, emulsify the broth as it is drawn off through the transfer hose. The difference between chintan and paitan is covered in detail in how to make chintan and paitan with valve and pressure control.

Depressurize by natural depressurization or water cooling, as in the product’s procedure. For safety, the lid cannot be opened while pressurized. Follow the procedures in the instruction manual.

How switching tonkotsu prep to a pressure stockpot helps the business

Switching tonkotsu prep to a pressure stockpot lets you rethink three things: prep time, gas costs and how bones are used.

• Prep time: a simmer of about 8–12 hours becomes about 2–2.5 hours, cutting early starts and overtime just for broth.
• Gas: the pot can be held on low heat once the specified pressure is reached. At one shop that introduced Meiwa Seisakusho’s 90L model, the gas bill for tonkotsu broth went from ¥150,000 to ¥70,000 a month. See concrete ways to halve the gas bill for simmering broth for details.
• Use of bones: because the marrow dissolves thoroughly, it becomes easier to get a rich broth from the same amount of bones. Ways to cope with rising bone prices are covered in how to lower costs as pork and chicken bone prices rise.

Frequently asked questions

Summary: deliver heat to the bones rather than spending hours

It has long been thought that tonkotsu tastes good because it is simmered for hours, but what matters is softening the bones and dissolving the marrow and collagen. By cooking at about 120°C, a pressure stockpot does this in a short time.

Keep prep time and gas costs down while bringing the broth closer to your shop’s own tonkotsu through the bone mix, pressurizing time and how it is drawn off. Consider a pressure stockpot as the tool for that.

If you want to know how long your tonkotsu recipe would take and what broth it would produce, please contact us.

▼ Inquiries about trials and quotes
For customers outside Japan, Kitchen Techno, Meiwa Seisakusho’s sales agent, is your point of contact (English support available).
• Phone: Kitchen Techno +81-3-5285-3301 (10:00–17:00 Japan time, UTC+9)
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