Browse Techniques

Overrun is the percentage increase in volume that air incorporation gives your mix during churning. A base that starts at one litre and finishes at one and a half litres has 50% overrun. That number is not arbitrary decoration — it is the single most direct dial you have over final texture. Commercial soft-serve runs 80–100% overrun. Premium gelato holds 20–35%. Most restaurant ice creams sit between 30–60%, depending on fat content and intent. The mechanism driving texture is not just air bubbles. It is what happens to fat globules during churning. Raw cream holds fat inside intact globule membranes. As the dasher works the mix at sub-zero temperatures, mechanical shear destabilises those membranes and causes partial coalescence — fat globules cluster into a loose network without fully merging. That network does two things: it stabilises the air bubbles that give overrun, and it creates a semi-solid fat matrix that registers as body and richness on the palate. Modernist Cuisine Volume 3 (pages 234–241) spends considerable time on this fat-globule clustering mechanism, noting that ageing your base 4–24 hours at refrigerator temperature before churning allows the fat to crystallise partially inside the globules, which makes partial coalescence more efficient during the churn. Skip that ageing step and your globules skid past each other rather than clustering; you lose structural integrity and end up with either a greasy texture or a weak, icier product. Temperature during churning matters just as much. If your batch freezer canister is not cold enough at the start, the mix warms the barrel instead of the barrel cooling the mix, you get foam rather than a structured frozen emulsion, and overrun becomes meaningless because the air cells collapse the moment you pull the product. Fat percentage and emulsifier load set the ceiling on how much overrun your base can sustain before the structure breaks down. Egg-yolk lecithin from a full-yolk custard base gives you more emulsifier headroom than a Philadelphia-style (no-egg) base, which is why high-overrun gelato-style products usually lean heavier on yolk or add a secondary emulsifier such as mono- and diglycerides.

Liquid smoke is not a shortcut or a cheat — it is a fractioned, aqueous extract of wood pyrolysis condensate, and understanding its chemistry lets you use it with precision rather than luck. When wood combusts between roughly 300°C and 500°C, cellulose, hemicellulose, and lignin break down into three families of compounds that define smoke flavor: phenols (guaiacol, syringol, 4-methylguaiacol), carbonyls (acetaldehyde, diacetyl, furfural), and acids (acetic, formic, propionic). Commercial liquid smoke is produced by condensing these volatiles in water, then fractioning out tars and polycyclic aromatic hydrocarbons — the carcinogenic portion — through aqueous scrubbing and filtration. What remains is pH-acidic (typically 2.5–3.5), phenol-rich, and carbonyl-forward. In the kitchen, that chemistry matters in three direct ways. First, the phenols are your primary smoke character — guaiacol reads as medicinal-sweet, syringol as the deeper, woodier bass note. The wood source determines the phenol ratio: hickory is guaiacol-heavy; mesquite pushes methylguaiacol; applewood carries higher syringol fractions. Second, carbonyls drive color. Diacetyl and short-chain aldehydes participate in Maillard-adjacent browning reactions with amino acids on meat surfaces; this is why a liquid smoke marinade on a protein will deepen color in the oven faster than an unmarinated piece at identical temperature. Third, the acidity matters structurally. Drop liquid smoke into a protein brine and that pH actively denatures surface proteins slightly, opening up texture and accelerating cure penetration — documented in Modernist Cuisine's treatment of brine chemistry (Myhrvold, Young, and Bilet, Vol. 3). The practical consequence: dose by phenol impact, not by volume. A hickory distillate at 10% phenol concentration needs half the volume of a lighter applewood product to hit the same aromatic threshold. Taste the liquid smoke neat against neutral fat (crème fraîche works well) before you build a dish around it. That fat-dilution test tells you immediately where the phenol saturation sits and whether the carbonyl note is diacetyl-buttery or furfural-grainy.

The Pacojet operates on a principle fundamentally different from churned ice cream. You freeze your base solid in a 800ml beaker at -22°C for a minimum of 24 hours — you need the entire mass hard through to the center. Then the machine's high-speed blade, spinning at 2,000 RPM, shaves the frozen block from the top down in controlled micro-layers, generating particles in the 1–10 micron range. This is not churning; there is no agitation of a semi-liquid. The blade physically cuts through fully solid material, and the friction energy is managed precisely enough that the particles never fully melt — they coat in a film of liquid and re-integrate into an aerated mass. What you get is a texture with no detectable crystal structure on the palate, a fat globule network that has been mechanically distributed rather than emulsified through temperature manipulation, and a stable overrun built entirely from incorporated air during the pacotizing spin rather than from a pre-aerated base. Modernist Cuisine (Myhrvold, Young, and Bilet) documents that the resulting particle size approaches that of commercial homogenized dairy — around 2 microns — which is why the mouthfeel reads as smoother than almost anything achievable by conventional batch freezing. The technique also allows you to process bases with little to no added stabilizer because the micro-particle structure itself provides textural stability at serving temperature. You can pacotize any fat-bearing or water-bearing frozen preparation: raw fish, truffle paste, chlorophyll bases, nut butters, reduced stocks. The machine does not care what the base is as long as it is frozen solid and the fat-to-water ratio is not so extreme that it shears without cohering. In service, you process one portion (one to four 'pacos' of the blade) directly before plating, meaning the ice cream is made to order and served at its structural peak, without holding time degrading crystal formation.

When you seal a vegetable in a chamber vacuum machine with a pickling or brine liquid and pull the pressure down, the intercellular gases inside the plant tissue are drawn out. The moment you vent the chamber and atmospheric pressure slams back in, that liquid gets driven into the spaces the gas just vacated. You're not waiting for osmosis to do its slow, cell-by-cell work over 24 hours. You're mechanically flooding the tissue. The result: a cucumber that carries seasoned brine in two minutes rather than two days, or a watermelon radish slice that reads simultaneously crisp and deeply brined without the softening that extended salt-cure produces. For lacto-fermentation applications, the technique is slightly different in intent. You're using vacuum cycles to ensure your salt brine saturates the vegetable evenly and immediately, so that the anaerobic environment needed for Lactobacillus activity starts uniform across the whole batch rather than migrating from the surface inward. You still need fermentation time — vacuum doesn't create lactic acid, it just sets the stage faster and more consistently. The critical variable is the porosity and cell structure of the vegetable. Dense, low-gas tissues like beet or turnip take multiple cycles or require a higher brine concentration to show meaningful impregnation. High-porosity tissues — cucumber, watermelon rind, summer squash — respond in a single cycle. Myhrvold, Young, and Bilet detail the cellular mechanics in Modernist Cuisine, noting that the intercellular air volume of most vegetables ranges from five to forty percent, which directly governs how much liquid can be pulled in. What you get is control over texture that brining alone cannot give you. Because the liquid enters under pressure rather than through osmotic draw, the cell walls themselves experience less turgor loss. The vegetable stays crisper. The flavour is distributed throughout the flesh, not concentrated at the surface the way a quick surface-brine tends to be. For a quick-service or tasting-menu context where a pickle must read both structurally clean and fully seasoned, this is the technique that gets you there without compromise.