With the helpful interference of the lactoglobulins, the casein particles can only bond to each other at a few spots, and so gather not in clusters but in a fine matrix of chains that is much better at retaining liquid in its small interstices The Fermentation Once the milk has been heated, it’s cooled down to the desired fermentation temperature, the bacteria are added (often in a portion of the previous batch), and the milk kept warm until it sets The fermentation temperature has a strong influence on yogurt consistency At the maximum temperature well tolerated by the bacteria, 104–113ºF/40–45ºC, the bacteria grow and produce lactic acid rapidly, and the milk proteins gel in just two or three hours; at 86ºF/30ºC, the bacteria work far more slowly, and the milk takes up to 18 hours to set Rapid gelling produces a relatively coarse protein network whose few thick strands give it firmness but also readily leak whey; slow gelling produces a finer, more delicate, more intricately branched network whose individual strands are weaker but whose smaller pores are better at retaining the whey Frozen Yogurt Frozen yogurt became popular in the 1970s and ’80s as a low-fat, “healthy” alternative to ice cream In fact, frozen yogurt is essentially ice milk whose mix includes a small dose of yogurt; the standard proportion is 4 to 1 Depending on the mixing procedure, the yogurt bacteria may survive in large numbers or be largely eliminated Soured Creams and Buttermilk, Including Crème Frche Before the advent of the centrifugal separator, butter was made in western Europe by allowing raw milk to stand overnight or longer, skimming off the cream that rose to the top, and churning the cream During the ... Before the advent of the centrifugal separator, butter was made in western Europe by allowing raw milk to stand overnight or longer, skimming off the cream that rose to the top, and churning the cream... small dose of yogurt; the standard proportion is 4 to 1 Depending on the mixing procedure, the yogurt bacteria may survive in large numbers or be largely eliminated Soured Creams and Buttermilk, Including Crème Frche... intricately branched network whose individual strands are weaker but whose smaller pores are better at retaining the whey Frozen Yogurt Frozen yogurt became popular in the 1970s and ’80s as a low-fat, “healthy”