Food Structure


The types of Labneh were made from full-fat cow's milk: (a) traditional Labneh was produced by straining cold yoghurt at 7°C in a cloth bag, and (b) UF Labnehs were produced by ultrafiltration (UF) of warm yoghurt at 35°, 40°, 45°, 50°, and 55°C. The UF Labnehs contained 22.7- 23.9% total solids, 7.8-8.3% protein, and 10.6-11.3% fat as compared to 25.3%, 9.1 %, and 11.9%, respectively, intraditional Labneh. Homogenization of the experimental Labneh samples in an ALM homogenizer using the D-170 or D-280 ,heads made the products smoother than unhomogenized Labnebs. Scanning electron microscopy revealed that the largest and least uniform pores were present in traditional unhomogenized Labneh, where the protein clusters were relatively compact. Homogenization reduced the dimensions of the large pores and opened the structure of the protein clusters. Ultrafiltration of Labneh at elevated temperatures of 35° to 55°C resulted in an increase in the dimensions of the casein particles forming the protein matrix of the Labneh, evidently as the result of extended fermentation. Formation of complex casein particle chains, as observed by transmission electron microscopy, was associated with increased firmness of Labneh samples concentrated at temperatures above 45°C.