الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Conjugated linoleic acid (CLA) and its isomers are fatty acids found in meat, milk and dairy products. These fatty acids may have potential biological properties interesting for human health. It is well established that milk and dairy products are one of the major dietary sources of CLA but no work in Egypt has been conducted to assess the CLA content in different Egyptian processed cheese spreads and the factors that affect CLA content in these cheeses. Therefore, in the present study, a survey of Egyptian processed cheeses spreads available in the local market and its content of the CLA was done. Moreover, the effect of heating conditions and protein fractions on CLA content was studied in addition to studying the properties of the prepared processed cheese spreads rich in CLA content. Fifteen brands of processed cheese products were collected from the local market and analyzed. The obtained results revealed that CLA content in cheese brands labeled ”containing vegetable oils” ranged from 0.0 to 0.138% of the total fatty acids with an average of 0.056% while CLA content in brands labeled ”containing milk fat” ranged from 0.016 to 0.428% with an average of 0.158%. Concerning the effect of heating conditions and milk protein fractions, the obtained results clearly indicated that no significant effect on conjugated dienes could be detected as a result of heating butter oil or vegetable oils emulsion in either casein or whey protein concentrate solutions. Also it was observed that high pH and the presence of whey proteins would increase the development of conjugated dienes in simulated cheese models during heat treatment. In regards to the properties of the prepared processed cheese spread rich in CLA, the obtained results indicated that the use of increased percentage of CLA rich cheese curd in the cheese spread mixture decreased the total organoleptic scores of these cheeses inspite of its healthy effect.
Key words: conjugated linoleic acid, processed cheese ,heat-treatment,
vegetable oils, functional processed cheese spreads