On food and cooking the science and lore of the kitchen ( PDFDrive ) 1183

purees But both are marvels of mouth-filling pleasure Sauces Thickened with Droplets of Oil or Water: Emulsions The sauces we’ve examined so far are liquids thickened with a fine dispersion of solid materials: protein molecules, starch granules and molecules, particles of plant tissue and cell-wall molecules A very different thickening method is to fill the water-based liquid with droplets of oil, which are much more massive and slow-moving than individual molecules of water, impede their motion, and so create a thick and creamy consistency in the mixture as a whole Such a dispersion of one liquid in another is called an emulsion The word comes from the Latin for “to milk out,” and referred originally to the milky fluids that can be pressed from nuts and other plant tissues Milk, cream, and egg yolks are natural emulsions, while sauce emulsions include mayonnaise, hollandaise sauce, beurre blanc, and oil-and-vinegar salad dressings Modern chefs have applied the basic idea to the thickening of all kinds of liquids, and often actually describe the result on the menu as an emulsion, a word that lingers on the tongue longer than sauce does Emulsified sauces offer a special challenge to the cook: unlike sauces thickened with solids, emulsions are basically unstable Whisk oil and a little vinegar together in a bowl, and the vinegar forms droplets in the oil: but they soon sink and coalesce, and in a few minutes the two liquids have separated again Cooks not only have to form the emulsion, they also have to prevent the emulsion from being undone by the basic incompatibility of the two liquids The Nature of Emulsions ... Modern chefs have applied the basic idea to the thickening of all kinds of liquids, and often actually describe the result on the menu as an emulsion, a word that lingers on the tongue longer than sauce does... bowl, and the vinegar forms droplets in the oil: but they soon sink and coalesce, and in a few minutes the two liquids have separated again Cooks not only have to form the emulsion, they also have to prevent the emulsion from being undone by the basic...other plant tissues Milk, cream, and egg yolks are natural emulsions, while sauce emulsions include mayonnaise, hollandaise sauce, beurre blanc, and oil -and- vinegar salad dressings