Dairy Chemistry And Biochemistry

120 DAIRY CHEMISTRY AND BIOCHEMISTRY

tropical regions, butter grains or cream are heated to remove all the water;
the resulting product is called ‘ghee’, a crude form of butter oil.
The cream used for butter may be fresh (- pH 6.6) or ripened (fermented;

• pH 4.6), yielding ‘sweet-cream’ and ‘ripened cream (lactic)’ butter, respect-
  ively. Sweet-cream butter is most common in English-speaking countries but
  ripened cream butter is more popular elsewhere. Traditionally, the cream for
  ripened cream butter was fermented by the natural microflora, which was
  variable. Product quality and consistency were improved by the introduc-
  tion in the 1880s of cultures (starters) of selected lactic acid bacteria, which
  produce lactic acid from lactose and diacetyl (the principal flavour compo-
  nent in ripened cream butter) from citric acid. A flavour concentrate,
  containing lactic acid and diacetyl, is now frequently used in the manufac-
  ture of ripened cream butter, to facilitate production schedules and improve
  consistency.
  Butter manufacture or churning essentially involves phase inversion, i.e.
  the conversion of the oil-in-water emulsion of cream to a water-in-oil
  emulsion. Inversion is achieved by some form of mechanical agitation which
  denudes some of the globules of their stabilizing membrane; the denuded
  globules coalesce to form butter grains, entrapping some globular fat. The
  butter grains are then kneaded (‘worked’) which releases fat liquid at room
  temperature. Depending on temperature and on the method and extent of

Figure 3.27 Schematic representation of the structure of butter. 1, fat globule; 2, membrane; 3,
aqueous droplet; 4, fat crystals; 5, air cell. (Modified from Mulder and Walstra, 1974.)