Thesis (Ph.D.) - Cairo University - Faculty of Agriculture - Department of Dairy

The present study was conducted to explore the quality and safety of vegetable oil-based Egyptian soft cheeses that were manufactured from available vegetable oils in the Egyptian market. This study was divided into two parts. In the first part, fatty acid composition and quality characteristics of four commercial vegetable oils and vegetable oil-based cheeses in the Egyptian market were evaluated. A total of 9 local soft cheese samples (from factories or laboratories) were collected from Egyptian market. For comparison, milk fat(MFC), shortening oil(SHOC) and cocoa butter substitutes oil(CBSOC) based-cheeses were manufactured. Both coconut oil (CO) and palm oil (PO) samples showed a significant elevation in peroxide values compared to cocoa butter substitute oil (CBSO) and shortening oil (SHO) samples. Both CBSO and CBSOC showed significant resistance to oxidation as indicated from results of oxidative stability (p<0.05). CBSO was characterized with extremely high lauric, myristic and stearic fatty acids content, but the SHO was characterized with a high content of palmitic and stearic fatty acids. The highest quantity of TUSFA was recorded for oleic acid in SHO compared to CBSO. Also, both CBSO and CBSOC showed the highest content of total trans fatty acids(TTFA). All samples were not in agreement with Codex standards for un-saponifiable matter content (except PO) and they showed higher insoluble impurities content than the maximum limit stated by Codex standards. In the second part, the effects of Egyptian soft cheese containing vegetable oils (30% or 60% of the diet) on lipid profile, histopathology, lipid peroxidation and liver and kidneys functions were evaluated. Rats were fed on basal diet (control), basal diets containing (MFC), (SHOC), vegetable oil-based cheese collected from local market (LMVC), (CBSOC), (SHO) or (CBSO) for 40 days. There was no significant effect of experimental diets containing 30% cheese. The experimental diets containing 60% cheese showed significant increase in body weight gain and feed efficiency ratio when compared with control. Triglycerides levels were significantly higher when rats fed on LMVC (150%) and CBSO (96.8%) compared with control. LMVC and CBSO diets tended to increase total cholesterol (10% and 32% vs. control) and VLDL (128% and 109% vs. control), respectively. CBSO diet slightly increased MDA (25%) compared with control. Histopathological examination showed more serious and negative effects of CBSO diet on liver and kidneys

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