Microstructure and chemical changes in Karish cheese prepared from reconstituted ultrafiltrated milk

Retentate was prepared from reconstituted skim milk by ultrafiltration [UF] and used in Kariesh cheese making. Microstructure and protein hydrolysis in cheese were examined when fresh and after 3 and 6 weeks of ripening. UF cheese had better quality than that made from reconstituted milk by the conventional methods. Protein degradation was more evident in UF cheese resulting in more liberation of free amino acids. The free amino acids released from cheeses, not only differed in their quantitative values but also in their nature and numbers. Thirteen free amino acids appeared in young cheeses then increased to 16 during ripening. TEM and SEM micrographs showed no apparent differences in the microstructure and the fusion of protein particles in both cheese when fresh and during ripening. In Kariesh cheese the fusion of protein advanced more extensively at surface that in the interior body of cheese

effect of sodium chloride on the free amino acid and the free fatty acid contents of Domiati cheese

Domiati cheese was made from milk containing 5, 10, and 15% sodium chloride. The formation of the free amino acids and fatty acids and the micro flora in fresh cheese and after 1 and 2 months were studied. The total free amino acids and fatty acids of cheese increased during storage but at a slow rate with increasing sodium chloride content. Increasing the sodium chloride content of cheese increased the formation of free lysine, but had unclear effect on histidine, and decreased the concentration of the other free amino acids in cheese. Also, the high salt content of cheese was accompanied with the appearance of therionine; serine; valine and methionine at advanced stage of storage. The total free volatile fatty acids [TFVFA] and non volatile fatty acids [NVFA] were affected by sodium chloride content of cheese. The ratio of volatile free fatty acids [VFEA] [C[2]-C[10]] to total free fatty acids [TFFA] decreased in cheese with high salt content. The count of the detectable microbial groups [total bacterial count; lipolytic and proteolytic bacteria, and yeasts and moulds] decreased by storage period and sodium chloride content of cheese. The addition of 10% sodium chloride to cheese milk greatly reduced the count of the above microbial groups compared to cheese with 5% sodium chloride. Further addition of sodium chloride [15%] did not cause more reduction in the bacterial count than 10%