Stock is bones, mirepoix, water, and time — the clear, deeply flavoured liquid that underpins every sauce, soup, braise, and risotto in professional cooking. It is not broth (which includes meat and is seasoned for drinking) and it is not bone broth (a modern marketing term for long-cooked stock). Stock is unseasoned, gelatin-rich liquid designed to be a building block, not a finished product. White stock: raw bones, cold water start, 4–6 hours for chicken (Gallus gallus domesticus), 8–12 hours for veal or beef. Brown stock: bones roasted at 220°C (425°F) until deeply caramelised, mirepoix roasted alongside, then simmered 8–12 hours. The cold-water start is where the dish lives or dies. Proteins in the bones are soluble in cold water; as the temperature rises slowly, these proteins denature, coagulate, and float to the surface as grey scum. Starting with cold water and bringing it to a simmer gradually extracts the maximum amount of protein and gives you the opportunity to skim it away, producing a clear stock. Dumping bones into boiling water shocks the proteins, which fragment into tiny particles that remain suspended — producing a permanently cloudy, muddy-tasting stock. Quality hierarchy for bones: 1) Veal bones (especially knuckle joints) — the gold standard. Young animals have more collagen than older ones, and veal knuckles are almost pure collagen. A properly made veal stock gels solid at refrigerator temperature, a quality called body that no other bone matches. 2) Chicken carcasses and feet — feet are collagen-rich and produce excellent body. Carcasses from roasted chickens give darker, more flavourful stock. 3) Beef marrow bones and oxtail — richer and more assertive than veal, used for brown stock and demi-glace. 4) Fish bones (sole, turbot, halibut — flat white fish only) — 20–25 minutes maximum. Salmon and oily fish bones produce bitter, fishy stock. The mirepoix (2 parts onion, 1 part carrot, 1 part celery) goes in during the last 45–60 minutes for white stock, or is roasted and added at the beginning for brown. Adding vegetables at the start of a 12-hour simmer extracts their flavour in the first hour and their bitterness for the remaining eleven. Skimming: every 20–30 minutes during the first 2 hours, then hourly. Use a ladle, not a spoon. Skim from the edges where the scum accumulates. Never stir the stock — stirring emulsifies the fat and breaks up the scum, reincorporating impurities. The simmer should show lazy bubbles breaking the surface every few seconds, never a rolling boil. Boiling agitates the fat into permanent emulsion, producing cloudy stock.
Quality hierarchy: 1) Bone preparation — for white stock, blanch bones in cold water, bring to a boil, drain, rinse under cold water to remove surface impurities, then start fresh with new cold water. This double-start produces the cleanest stock. For brown stock, roast bones at 220°C (425°F) for 40–60 minutes, turning once, until deep mahogany. Add tomato paste to the bones in the last 15 minutes for colour and acidity. 2) Water ratio — bones should be covered by 5–8cm (2–3 inches) of cold water. More water produces diluted stock; less produces concentrated but insufficient yield. Do not add water during cooking — this dilutes the developing gelatin concentration. 3) Temperature discipline — 85–95°C (185–203°F) internal temperature, maintained for the entire cooking time. Use a probe thermometer clipped to the pot wall. The surface shows occasional lazy bubbles. Anything more vigorous and you are boiling, not simmering. 4) The remouillage — after straining the first stock, cover the bones with fresh cold water and simmer for half the original time. This second extraction (remouillage, literally “rewetting”) produces a lighter stock used as the water for the next batch of stock. Nothing is wasted. 5) Straining and cooling — strain through a fine-mesh sieve lined with cheesecloth. Do not press the solids (pressing squeezes out cloudy, fatty liquid). Cool rapidly by placing the strained stock pot in an ice bath, stirring occasionally. Stock must pass through the danger zone (60–10°C / 140–50°F) within 2 hours for food safety.
Chicken feet are the secret weapon. They are almost pure collagen and produce stock with extraordinary body — the kind that gels so firmly in the fridge you could slice it. Add 500g of feet to any chicken stock for a dramatic improvement in richness and mouthfeel. Blanch the feet first. The overnight test: properly made stock, refrigerated, should be solid enough to jiggle like set gelatin when you shake the container. If it’s still liquid, the stock lacks body and was either too dilute, not cooked long enough, or made from bones with insufficient collagen. For demi-glace: reduce brown veal stock by half, combine with an equal volume of espagnole sauce, then reduce again by half. Or for the modern shortcut: simply reduce brown veal stock by 90% until it coats a spoon with a dark, glossy, intensely flavoured glaze (glace de viande). One tablespoon of this concentrate stirred into any pan sauce transforms it. Store glace de viande in ice cube trays in the freezer. Each cube is a depth charge of flavour.
Starting with hot or boiling water — this produces permanently cloudy stock. The cold-water start is the foundation of the entire technique. Boiling instead of simmering — a rolling boil emulsifies fat, suspends impurities, and breaks down collagen too aggressively, producing a greasy, cloudy, muddy-tasting stock. Not skimming — the grey scum that rises in the first hour contains coagulated blood proteins, impurities, and denatured albumins. If not removed, they remain suspended and produce off-flavours. Stirring the pot — stirring breaks up the fat layer, reincorporates skimmed impurities, and agitates the stock. Ladle from the surface, never stir. Adding salt — stock is never seasoned. It is a building block that will be reduced, added to sauces, and combined with other ingredients. Salting stock produces inedibly salty results when reduced. Using oily fish bones — salmon, mackerel, sardine, and bluefish bones produce bitter, fishy, unpleasant stock. Flat white fish only.