On food and cooking the science and lore of the kitchen ( PDFDrive ) 45

without curdling The Caseins The casein family includes four different kinds of proteins that gather together into microscopic family units called micelles Each casein micelle contains a few thousand individual protein molecules, and measures about a ten thousandth of a millimeter across, about one-fiftieth the size of a fat globule Around a tenth of the volume of milk is taken up by casein micelles Much of the calcium in milk is in the micelles, where it acts as a kind of glue holding the protein molecules together One portion of calcium binds individual protein molecules together into small clusters of 15 to 25 Another portion then helps pull several hundred of the clusters together to form the micelle (which is also held together by the water-avoiding hydrophobic portions of the proteins bonding to each other) Keeping Micelles Separate… One member of the casein family is especially influential in these gatherings That is kappa-casein, which caps the micelles once they reach a certain size, prevents them from growing larger, and keeps them dispersed and separate One end of the capping-casein molecule extends from the micelle out into the surrounding liquid, and forms a “hairy layer” with a negative electrical charge that repels other micelles A close-up view of milk Fat globules are suspended in a fluid made up of water, individual molecules of whey protein, bundles of casein protein molecules, and dissolved sugars and minerals …And Knitting Them Together in Curds The intricate structure of casein micelles can be disturbed in several ways that cause the .. .the casein family is especially influential in these gatherings That is kappa-casein, which caps the micelles once they reach a certain size, prevents them from growing larger, and keeps them dispersed and separate... keeps them dispersed and separate One end of the capping-casein molecule extends from the micelle out into the surrounding liquid, and forms a “hairy layer” with a negative electrical charge that repels other micelles... view of milk Fat globules are suspended in a fluid made up of water, individual molecules of whey protein, bundles of casein protein molecules, and dissolved sugars and minerals ? ?And Knitting Them Together in Curds The