Preparation of yogurt and quark

Process for the preparation of whipped quark having at least 200% unaided overrun comprising the steps of

• a. pasteurizing milk at a temperature of from about 55 to 80.degree.C for about one half of 1 minute to about 30 minutes,
• b. cooling the pasteurized milk to a temperature of about 5.degree.C to 50.degree.C,
• c. filtering the cooled pasteurized milk through a semi-permeable membrane which is permeable with respect to mineral salts and has a rejection characteristic of at least 0.8 with respect to milk proteins at a pressure of from 1 to 50 kg/cm.sup.2 to obtain a protein-rich residue separated from a mineral salt-rich filtrate,
• d. discontinuing the filtration when the volume of the residue is from 25 to 80 volume percent of the original volume of the milk, said residue containing from about 4% to about 15% protein,
• e. adjusting the temperature of the residue to 20.degree. to 35.degree.C,
• f. inoculating the residue with 0.1 to 5 weight percent of a quark culture lactic acid starter,
• g. incubating the inoculated residue for a period from 12 to 24 hours to a pH of about 4.5 to coagulate milk proteins,
• h. discontinuing further inoculation when coagulation is substantially complete and removing any whey separated, and
• i. whipping the coagulum obtained to an overrun of at least 200%.