On food and cooking the science and lore of the kitchen ( PDFDrive ) 1156

gel into a useless soup And agar gels remain solid at the ideal temperatures for bacterial growth, often around 100ºF/38ºC, a temperature at which gelatin begins to melt How did microbiologists come to use agar? In the late 19th century, Lina Hesse, the American wife of a German scientist, recalled the advice of family friends who had lived in Asia, and made agar jellies and puddings that stayed solid in the summer heat of Dresden Her husband relayed his wife’s suggestion to his boss, the pioneering microbiologist Robert Koch, who then used agar to isolate the bacterium that causes tuberculosis The Nature of Starch Starch molecules are long chains of thousands of glucose sugar molecules linked up together There are two kinds of starch molecules: long straight chains called amylose, and short, branched, bushy chains called amylopectin Plants deposit starch molecules in microscopic solid granules The size, shape, amylose and amylopectin contents, and cooking qualities of the starch granules vary from species to species Linear Amylose and Bushy Amylopectin The shapes of amylose and amylopectin molecules have a direct effect on their ability to thicken a sauce The straight amylose chains coil up into long helical structures when dissolved in water, but they retain their basically linear shape Their elongation makes it very likely that one chain will knock into another or into a granule: each sweeps through a relatively large volume of liquid By contrast, the branched shape of amylopectin makes for a compact target and therefore a molecule less likely to collide with others; and even if it does collide, it’s less likely to ... sauce The straight amylose chains coil up into long helical structures when dissolved in water, but they retain their basically linear shape Their elongation makes it very likely that one chain... cooking qualities of the starch granules vary from species to species Linear Amylose and Bushy Amylopectin The shapes of amylose and amylopectin molecules have a direct effect on their ability to... will knock into another or into a granule: each sweeps through a relatively large volume of liquid By contrast, the branched shape of amylopectin makes for a compact target and therefore a molecule