Sample Solution

effect on AOA of UF cheese. Khalifa and Wahdan7, reported that the addition of dehydrated cranberry fruit extract improved cheeses stability for oxidation. Cranberry fruit extract (containing phenolic compounds) has the ability to act as an antioxidant7. Khalifa and Wahdan7, also reported that cheese samples containing dehydrated cranberry fruit extract had lower acid value, lower proteolysis and lower lipolysis than control. These effects could be due to lower total viable counts, moisture content and titratable acidity7.

Fortified samples had lower lipolysis than control sample (Tables 8 and 9). Lipolysis increased in all samples during storage. However, increasing of lipolysis in fortified cheeses was less than control sample. Heating process that was applied to fortified cheeses, and also asparagus and tomato powders have a negative effect on lipolysis. Driessen23 reported that the thermization of milk (63 °C, 20 s) as well as the cooking of Emmental curd grains (51 °C for 20 min) inactivates the lipase enzymes. The main agents responsible for lipolysis of aged cheese are the intracellular bacterial lipases of cheese fat. Thermoduric bacterial lipases which survive during pasteurization are responsible for increasing of free fatty acid in cheese23.

Soluble nitrogen at pH 4.6 (SN) was used as an index of storage, includes peptides of medium to small molecular weight, proteoso peptones, whey proteins and free amino acids. These nitrogen compounds are the main results of rennet and plasmin proteolytic activity and/or microorganism peptidases31. Levels of SN of control samples did not significantly (P > 0.05) increase during storage (Tables 10 and 11). However, SN of fortified samples significantly increased (P < 0.05) during storage, which indi