Quark (dairy product) 6.1). Acidification allowed to continues until the pH reaches around 4.6, at which acidity level the casein proteins in the milk begins to precipitate. In Germany, the curd is continuously stirred to prevent it from getting hard, resulting in a thick, creamy texture. According to German regulations on cheese ("Käseverordnung"), "fresh cheeses" ("Frischkäse") such as quark or cottage cheese must contain at least 73% water in the fat-free component. German quark is usually sold in plastic tubs with most or all of the whey. This type of quark has the firmness of sour cream but is slightly drier, resulting in
Quark model for a variety of mixings. There may be hadrons which lie outside the quark model. Among these are the "glueballs" (which contain only valence gluons), "hybrids" (which contain valence quarks as well as gluons) and "exotic hadrons" (such as tetraquarks or pentaquarks). Quark model In particle physics, the quark model is a classification scheme for hadrons in terms of their valence quarks—the quarks and antiquarks which give rise to the quantum numbers of the hadrons. The quark model underlies "flavor SU(3)", or the "Eightfold Way", the successful classification scheme organizing the large number of lighter hadrons that were being discovered