MICROSTRUCTURE AND FIRMNESS OF LABNEH (HIGH SOLIDS YOGURT) MADE FROM COWS, GOATS AND SHEEPS MILKS BY A TRADITIONAL METHOD OR BY ULTRAFILTRATION

Two types of Labneh (high solids yoghurt) were made from goat's and sheep's milk: (a) traditional style Labneh was produced by straining yoghurt in a cloth bag, and (b) UF Labneh was made by ultrafiltration (UF) of warm yoghurt. A portion of all products were smoothened by a passage through a lactic curd homogenizer. Irrespective of their origin, the Labneh samples contained 20.5-22.5% total solids (including minerals and un-metabolized lactose), 6.7-8.2% protein, and 7.8-8.9% fat. Homogenization markedly decreased firmness of the goat's and sheep's Labnehs and is therefore not recommended in industrial production. Firmness of Labneh made from cow's milk was affected by homogenization to a lesser degree. Structures of goat's and sheep's Labneh, as revealed by electron microscopy, were similar to each other and less uniform than Labneh made from cow's milk. Homogenization increased the pore size of goat's and sheep's Labneh. There was an apparent relationship between pore size (as observed by scanning electron microscopy) and firmness.