Tonkotsu Pork Bone Broth

Fact-checked on paper only. This recipe has not been cooked or tested yet.

Why this works

Tonkotsu is pork bone broth. Kurume's Nankin Senryo stall is credited with the first tonkotsu soup in 1937, and the milky white style is said to have happened by accident in 1947, when a Sankyu shop owner left the heat on under the pot [Fukuoka Now]. The lesson holds at home: keep it at a hard rolling boil so the collagen and fat blend into the water. This is the reverse of a gentle Western stock [Glebe Kitchen]. A first blanch keeps the finished broth clean.

Yield: 3 liters (about 3 quarts) Times: prep PT30M, cook PT12H, total PT12H30M (ISO 8601)

Equipment

• 12 quart or larger stockpot
• Fine-mesh strainer or cheesecloth
• Large bowl for an ice bath, plus shallow pans
• Instant-read thermometer
• Tongs

Ingredients

• 2000 g (4.4 lb) pork neck bones and femur bones
• 1000 g (2.2 lb) pork trotters, split
• 6 L (6 qt) cold water for blanching
• 6 L (6 qt) cold water for the broth, plus hot water for topping up
• 50 g (2 large stalks) scallion greens
• 30 g (1 oz, a 2-inch piece) fresh ginger, sliced
• 20 g (6 cloves) garlic, smashed

Steps

1. Put the bones and trotters in the stockpot and cover with 6 liters of cold water.
2. Bring to a boil over high heat and boil hard for 5 to 10 minutes. Scum and blood will rise.
3. Drain, then rinse every bone under cold running water, scrubbing off clotted blood.
4. Wash the pot, return the bones, and add 6 liters of fresh cold water.
5. Bring to a rolling boil over high heat and hold a vigorous rolling boil.
6. After 2 hours, add the scallion greens, ginger and garlic.
7. Keep boiling for 10 to 12 hours total. Top up with hot water so the bones stay under water. The broth turns opaque and creamy.
8. Strain through a fine-mesh strainer, pressing gently on the solids.
9. Chill and store as described in the storage section.

What to watch for

• Skipping the blanch gives a murky, off-tasting broth.
• A simmer gives a thin stock, not tonkotsu. The boil is what emulsifies it.
• Bones above the waterline add nothing and can scorch. Keep topping up.
• Do not leave a pot at a hard boil unattended overnight on a gas burner.

Storage

• Chill fast. USDA's rule for any cooked food is to refrigerate within 2 hours (1 hour above 90 F) and to divide a big pot into shallow containers so it cools quickly [USDA FSIS, Keep Food Safe].
• For reference, USDA's plant guideline is 130 F to 80 F within 1.5 hours, then 80 F to 40 F within 5 hours. A home kitchen cannot measure that well, so use an ice bath and shallow pans [USDA FSIS Directive 7110.3].
• Refrigerate at 40 F (4 C) or below and use within 3 to 4 days. Freeze for best quality within 2 to 3 months [USDA FSIS, Leftovers and Food Safety].
• Reheat to 165 F (74 C) and bring soups to a rolling boil before serving [USDA FSIS, Leftovers and Food Safety]. Frozen broth can be reheated straight from the freezer.

Allergens: None inherent. Check the tare for soy, wheat and fish.

Pairs with

Shoyu tare or shio tare. Add mayu (black garlic oil) at the bowl for a classic pork bowl.

Sources

1. Fukuoka Now, tonkotsu ramen (1937 Kurume stall; milky broth by accident in 1947): https://www.fukuoka-now.com/en/rwc/deep-fukuoka/tonkotsu-ramen/
2. Glebe Kitchen, tonkotsu broth at home (a home-cook blog, used only for technique: 5 minute blanch, rolling boil): https://glebekitchen.com/tonkotsu-ramen-broth-home/
3. USDA FSIS, Keep Food Safe (2 hour / 1 hour chilling rule): https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/steps-keep-food-safe
4. USDA FSIS Directive 7110.3 cooling guidelines for plants (130 to 80 F in 1.5 hours, 80 to 40 F in 5 hours): https://meathaccp.wisc.edu/validation/assets/Directive%207110.pdf
5. USDA FSIS, Leftovers and Food Safety (refrigeration windows, reheating): https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/leftovers-and-food-safety

Citation links

• https://www.fukuoka-now.com/en/rwc/deep-fukuoka/tonkotsu-ramen/
• https://glebekitchen.com/tonkotsu-ramen-broth-home/
• https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/steps-keep-food-safe
• https://meathaccp.wisc.edu/validation/assets/Directive%207110.pdf
• https://www.fsis.usda.gov/food-safety/safe-food-handling-and-preparation/food-safety-basics/leftovers-and-food-safety