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العنوان
Physicochemical and microbial evaluation of edible fats and oils /
المؤلف
Abdel-Hafeez, Omar Ahmed
هيئة الاعداد
باحث / عمر احمد عبد الحفيظ
مشرف / احمد عبد الحميد احمد
مناقش / مصطفي خليل مصطفي
مناقش / محمد احمد حسني
الموضوع
Milk Hygiene.
تاريخ النشر
2022.
عدد الصفحات
77 p.:
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
البيطري
الناشر
تاريخ الإجازة
23/11/2022
مكان الإجازة
جامعة أسيوط - كلية الطب البيطري - الرقابة الصحية علي الالبان ومنتجاتها
الفهرس
Only 14 pages are availabe for public view

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Abstract

This investigation was applied to evaluate the sensory, physicochemical and microbial properties of cooking butter, hydrogenated oils, sunflower oils and corn oils, in which, 140 samples (35 each) were randomly collected from different localities in Assiut governorate, Egypt. in the period from November 2021 to April 2022.
The sensory evaluation showed that 68, 90.86, 87.85 and 89.29% of the examined cooking butter, hydrogenated oil, sunflower oil and corn oil samples were acceptable, respectively.
The physicochemical evaluation included pH, moisture content, free fatty acids%, acid value, peroxide value, p-ansidine value and total oxidation, and the obtained results were compared with the permissible limits of the Egyptian Standard specifications.
The average results for cooking butter and hydrogenated oil samples were 6.02 and 5.45 for pH, 24.16 and 0.33% for moisture%, respectively. Also, the average results for cooking butter, hydrogenated oil, sunflower oil and corn oil samples were 1.86, 0.4, 0.3 and 0.28% for free fatty acids%, 2.63, 0.57, 0.43 and 0.39 for acid value, 2.18, 1.83, 10.68 and 8.51 for
peroxide value, 2.23, 1.98, 3.15 and 3.81 for p-ansidine value, and 6.59,
5.61, 24.49 and 20.83 for total oxidation, respectively.
The Egyptian Standards cleared that 97.14 and 34.29% of the cooking butter and hydrogenated oil samples, respectively, were above the permissible limits for moisture%. Also, 97.14 and 100% of the cooking butter samples were above the permissible limits for peroxide value and free fatty acids%, respectively. It was found 28.57 and 11.43% of the hydrogenated oil and sunflower oil samples exceeded the permissible limit for acid value, respectively. Moreover, 48.57 and 37.14% of the sunflower oil and corn oil samples exceeded the permissible limit for peroxide value, respectively.
The microbial evaluation showed 57.14, 42.86, 42.86% of cooking butter samples were contaminated with coliforms, fecal coliforms and E. coli, respectively; and when compared with the Egyptian Standards, it was found that 48.57, 42.86 and 42.86% were unacceptable for coliforms, fecal coliforms and E. coli, respectively. While all the hydrogenated oil samples were free from coliforms, fecal coliforms and E. coli.
Moreover, 60 and 17.14% of the cooking butter and hydrogenated oil samples were contaminated with psychrotrophic bacteria with averages count 7.58×106 and 2.33×104 cfu/g. In addition, 97.14 and 65.71% of the cooking butter and hydrogenated oil samples were contaminated with yeasts & molds with averages count 4.55×106 and 1.3×105 cfu/g, respectively.
Part II (Exprimental part)
Effect of different frying times on the oxidative status of sunflower oil
The oxidative status of sunflower oil was increased by sequence frying times and the addition of rosemary essential oil to the sunflower oil was effective in reduction the oxidative status in the parameters of peroxide value, p-ansidine and total oxidation.