Acidulate

Acidulation is the act of adding a measured quantity of acid to water, creating an acidulated bath into which freshly cut produce is submerged to arrest oxidation. When the flesh of apples, pears, artichokes, celeriac, cardoons, salsify, and certain stone fruits is exposed to air, polyphenol oxidase (PPO) — a naturally occurring enzyme — catalyzes the reaction between phenolic compounds and atmospheric oxygen, producing brown or grey melanin-like pigments. Acid lowers the pH of the water below the optimal activity range of PPO (roughly pH 7–8), effectively inactivating the enzyme and preserving the visual appeal of the cut ingredient. Lemon juice is the most common acidulant in Western kitchens and contributes approximately 5–6% citric acid; a ratio of 1 tablespoon (15 ml) per 1 litre (1 quart) of cold water is a practical standard. White wine vinegar or cider vinegar at the same volume works equally well where a slight vinegary note is acceptable. For delicate fruits served raw — sliced pears in a salad, apple fans in a tarte tatin mise en place — the lemon-water bath also imparts a subtle brightness that reads as freshness. In professional kitchens, acidulated water (eau acidulée) is kept at hand continuously during vegetable butchery. It is not a cooking step but a holding technique: produce moves from the acidulated bath directly into the next preparation stage.

“Working quickly, drop each artichoke heart into a bowl of acidulated water — one lemon's juice per litre — to prevent it from blackening before you reach the braising pan.”

• techniquesBlanching
• IngredientArtichoke
• RatioAcid Balance

1. 1.On Food and Cooking — Harold McGee
2. 2.The Professional Chef — The Culinary Institute of America
3. 3.Jacques Pépin: New Complete Techniques — Jacques Pépin
4. 4.Vegetables — James Peterson

Confidence: high