Antifreeze polypeptide-expressing microorganisms useful in fermentation and freezing of foods

A method for preparing frozen yogurt comprising the steps of:

• (a) contacting milk with a microorganism that secretes a fish antifreeze polypeptide into the milk and that ferments the milk;
• (b) incubating the milk with the microorganism under conditions in which fermentation takes place so that yogurt is produced having the fish antifreeze polypeptide present in an amount effective at preventing or inhibiting ice-crystal formation in the yogurt during storage;
• and, then
• (c) freezing the yogurt at a temperature below -5.degree. C. so as to produce frozen yogurt;
• wherein the microorganism is a member selected from the group consisting of Streptococcus cremoris, Streptococcus lactis, Streptococcus thermophilus, Leuconostoc citrovorum, Leuconostoc mesenteroides, Lactobacillus acidophilus, Lactobacilus bulgaricus, Lactobacillus casei, Lactobacillus jugurti, Lactobacillus lactis, Bifidobacterium bifidum, Bifidobacterium breve and Bifidobacterium longum.