A pressure cooker elevates the boiling point of water from 100°C to approximately 121°C at 1 atmosphere of additional pressure. This higher temperature accelerates every thermally-driven reaction in cooking — collagen-to-gelatin conversion, Maillard reactions in liquid (impossible at atmospheric pressure), caramelisation of dissolved sugars, and the extraction of flavour compounds from aromatics. A beef stock that takes 8 hours at atmospheric pressure takes 2 hours in a pressure cooker — and produces different flavour compounds because of the higher temperature.
**Pressure cooker applications ranked by benefit:** 1. **Legumes:** Dried beans that take 90 minutes at atmospheric pressure cook in 15–20 minutes. The cell walls break down more completely, producing a creamier interior texture. 2. **Collagen-rich stocks:** 2-hour beef stock vs. 8-hour conventional. Comparable gelatin yield; different flavour profile (more roasted, slightly different aromatic). 3. **Root vegetables:** Caramelisation of dissolved sugars at 121°C produces noticeably sweeter, more complex carrots and beets. Conventional boiling cannot achieve this. 4. **Infusions and extractions:** Alcohol extraction of flavour compounds (pressure-cooked bitters, pressure-cooked spirits infusions) in 30 minutes vs. months. **The Maillard in liquid:** The Modernist Cuisine demonstration: equal amounts of onion browned in a conventional pan (dry Maillard) vs. onion "pressure caramelised" (wet Maillard at 121°C in the sealed cooker). Both produce deep amber colour and complex sweetness through Maillard reactions — the pressure caramelisation achieves this without any browning, entirely in liquid. The flavour is slightly different (no surface char, more even distribution of compounds) but the Maillard chemistry is identical.
Modernist Cuisine