On food and cooking the science and lore of the kitchen ( PDFDrive ) 1174

Some of the most delicious sauces we eat, including tomato sauces and applesauce, are made simply by crushing fruits and vegetables Crushing, or pureeing, frees the juices from the cells of the fruit or vegetable, and breaks the cell walls into fragments that become suspended in the juices and block their flow, so giving them some thickness Crushed nuts and spices have no juices of their own, but they thicken a liquid to which they’re added by absorbing some of its water and providing dry cell particles that obstruct the liquid’s flow Until recently, most purees of plant tissue would have been made by cooking the tissue to soften it, and then either grinding it in a mortar or forcing it through a fine sieve Raw purees could only be made from fruits softened by ripening, or from brittle nuts Today’s cooks can use powerful machines — blenders, food processors — to puree any fruit or vegetable or seed with ease, whether they’re raw or cooked Plant Particles: Coarse and Inefficient Thickeners Compared to the other ways of thickening, simple pureeing tends to produce a coarse sauce that more readily separates into solid particles and thin fluid The solid fragments of plant cell walls are clumps of many thousands of carbohydrate and protein molecules If those molecules were dispersed separately and finely throughout the fluid — as gelatin or starch molecules are in other sauces — they would bind many more water molecules, get tangled up in each other, and be far too small for the tongue to detect as particles But plant-cell fragments range from 0.01 to 1 millimeter across; they give a grainy impression on the tongue and they’re far less efficient than individual molecules at binding water or interfering with fluid flow And ... particles and thin fluid The solid fragments of plant cell walls are clumps of many thousands of carbohydrate and protein molecules If those molecules were dispersed separately and finely throughout the fluid —... 0.01 to 1 millimeter across; they give a grainy impression on the tongue and they’re far less efficient than individual molecules at binding water or interfering with fluid flow And ... as gelatin or starch molecules are in other sauces — they would bind many more water molecules, get tangled up in each other, and be far too small for the tongue to detect as particles But plant-cell fragments range from