الفهرس 
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Abstract
Vegetable cold pressed oils of sesame, pumpkin, lin and rape and essential oils of ginger, fenugreek and black cumin seeds were evaluated for their physicochemical properties, oxidative stability index (OSI), fatty acids composition (FA) and tocopherols &total phenolic contents (TPC) in the first part of this study. The obtained results can be summarized as follows: The oleic and linoleic fatty acids were found to be the predominant fatty acids (% of total fatty acids) in all the evaluated cold pressed oils except flaxseed oil where the predominant fatty acids was linolenic acid C18:3 and represented the highest concentration (51.1%). Results indicated that pumpkin seed oil had the highest total saturated fatty acids 13.8% of the total fatty acids; whereas rapeseed oil had the highest total monounsaturated fatty acids amounted to 60.8 %. Linseed oil showed the highest polyunsaturated fatty acids 67.3%. There were significant differences in colour, peroxide value, free fatty acids percentage, saponification value and specific extinction of cold-pressed oils at 232 and 270 nm. The cold pressed pumpkin seed oil had considerably higher specific extinctions than those of other cold pressed oils at both wavelengths. Black cumin seed oil showed the highest free fatty acid (7.25%) and peroxide value (31.45meq.O2/kg oil)) and the lowest total of tocopherols content (1624.8 mg /kg). Ginger oils exhibited the strongest DPPH scavenging capacity of 85.7%, the highest OSI of 17.5 hour at 110 oC and contained the highest TPC and total tocopherols of 1266.7 mg/kg, 16562.8 mg/kg respectively. In conclusion, cold-pressed pumpkin, sesame, lin and rape are healthy oils as they are rich in unsaturated fatty acids namely Linoleic acid (C18:2), α-linolenic acid (C18:3) and oleic acid (C18:1) respectively. The cold-pressed oils had significantly different (P < 0.05) levels of bioactive compounds such as tocopherols and total phenolic compounds. The oil samples were significantly different in colour due to the bioactive compounds such as tocopherols and reflecting that lin and rapeseed oils are yellow in colour. All the oils indicated desirable quality as they had very small percentages of free fatty acids percentage and low values of oxidative stability tests. In the second part, the effect of replacement of shortening fat with 0.0, 30 and 50% of both sesame and pumpkin oils (on fat basis) on some quality characteristics and fatty acid profile of biscuit was evaluated. Addition of 30% of cold pressed sesame and pumpkin oils gave the highest overall quality score of sensory evaluation. On replacing the fat with 50% sesame and pumpkin oil, there was a decrease in saturated fatty acids and increase in unsaturated fatty acids, particularly linoleic acid. The replacement of shortening fat of biscuit with different levels of both sesame and pumpkin cold pressed oils showed a significant reduction in the saturated fatty acids percent. The fatty acid profile of biscuit with 30% sesame oil was better than the control biscuit as there was a significant reduction in palmitic acid content and increase in essential fatty acids (EFA) content.
In the third part, the changes in the quality of mackerel fish burgers treated with different levels of cold pressed ginger oil during storage at 4°C were investigated, in terms of sensory evaluation, biochemical characteristics such as free fatty acids%, peroxide value (AV), thiobarbituric acid (TBA), Trimethyl amine (TMA), total volatile basic nitrogen (TVB-N), and total bacterial count. The obtained results can be summarized as follows: There was no significant difference between groups in terms of moisture, protein fat and ash contents. However, significant differences were found between groups in terms of pH, TVB-N, peroxide value and TBA values during storage at 4°C for 21 days. It was observed that the addition of ginger oil at 2% and 3% to fish burgers mince increased the shelf life of the products and enhanced the sensory quality of the resultant burgers. Results showed that the TVB-N level did not exceed acceptability limit (30–35mg /100g) for burgers treated with 3% cold pressed ginger oil. Control Mackerel fish burgers showed higher free fatty acids %, PV, TBA values ,TMA, TVB-N values as compared with burgers containing cold pressed ginger oils. Thus, the addition of ginger oil at a ratio of 2 and 3% was effective in controlling these biochemical indices and extending the shelf life of mackerel fish burgers. In conclusion, the addition of 3% ginger oil to fish burgers allowed for an acceptable shelf life for up to 21 days at 4°C and gave the best organoleptic properties.