الفهرس | Only 14 pages are availabe for public view |
Abstract The present thesis comprises four chapters: Chapter 1 • Includes an introduction to the importance of food and characterization of food security and food pollution issues in Egypt. • An introduction to natural food additives used for treatment, as well as their different properties. • Finally, states the main objectives of the study which were asfollows: -To suggest methods of analysis of the studied organic pollutants. - Studying the different factors affecting efficiency of extraction methods of the studied organic pollutants. -Validation and application of the optimized proposed extraction method on real food samples. -To assess the contamination level of processed food in Egyptian local markets by organic pollutants. -To investigate the possibility of eliminating or suppressing the presence of these pollutants in food using natural food additives. Chapter 2 Comprises the literature survey on the sources and hazardous of some organic pollutants as polycyclic aromatic hydrocarbons (PAHs) on the environment. A review of different PAHs extraction methods from polluted environment, different techniques used for PAHs determination were also included with variables treatment methods for food. Chapter 3 Describes the reagents and chemicals, instruments, extraction methods, analytical methods and treatment methods applied during this study. Chapter 4 Represents the results and discussion of the present study which can be divided into four parts summarized as follows:- Part(I): Optimization and validation of an extraction method for the analysis of polycyclic aromatic hydrocarbons in potato chips using gas chromatography-mass spectrometry • Optimization of the PAHs extraction conditions using full factorial design with variation of three factors at two levels, factors including sample weight, solvent volume and extraction time. • After applying full factorial design it was found that the optimum extraction method was ultra-sonication assisted extraction with optimized conditions of 5 g sample weight, 40 mL extraction solvent and 40 minutes sonicationtime. • Different parameters were calculated to validate the applied extraction method including limit of detection (LOD) which ranged from 0.017 to 0.46 μg/mL and limit of quantitation (LOQ) which ranged from 0.05 to 1.38μg/mL. • Application of validated extraction methods on commercial potato chips using GC/MS MS. • PAHs quantitation method was applied after verification of gas chromatography and mass spectrometer parameters including type of GC column, collision energy, retention time segmentation and EM gain factor. • Extracted potato chips samples under optimized conditions contained PAHs at the range of 30 to 387ng/g. Part II: Distribution and health hazards of polycyclic aromatic hydrocarbons in Egyptian milk and dairy-based products • A market-basket study was carried out to evaluate the contamination levels of PAHs found in Egyptian dairy basedproducts. • Quechers method was chosen for milk extraction process, the obtained data showed that the total amount of PAHs was within the range of 1.3 - 8.2 µg/g. • The obtained results proved that, the highest mean levels of PAHs were detected in powdered milk (8.2 μg/g) followed by UHT milk and milk beverage (6.07μg/g). • The lowest level was detected in unsmoked cheese and yogurt (1.3μg/g). • Estimated daily intake (EDI) of PAHs was calculated for different children aged categories (1 to 10 years) to evaluate the carcinogenicrisk. • The calculated EDI with respect to benzo (a) pyrene was ranged from 0.058 to 0.31 mg/day. Part (III): Optimized conditions of using different food additives for suppressing the accumulation of Polycyclic Aromatic Compounds in potatoes during frying • Effect of frying process on formation levels of PAHs was studied. • Detoxification of PAHs using BHA and TBHQ as oil additives was successfully achieved. • Detoxification of PAHs using organic acids and fruit vinegars as fresh potatoes additives was done with removal efficiency up to96%. • The different operating conditions affecting treatment process of PAHs wereevaluated. • The performed studies suggested that acidic pH of marinating solution with long marinating time (10 minute) showed the highest removal efficiency. • Assessment of antioxidant activity of organic acids and fruit vinegars wasachieved. • Screening of bioactive components in fruit vinegars was performed with the assist of GC/MS MS. Part (IV): Detoxification of polycyclic aromatic compounds in polluted milk samples using different natural food additives • Effect of boiling process on formation levels of PAHs wasinvestigated. • Effect of using different types of food additives including vanilla, cinnamon and mastic on milk detoxification of PAHs wasexamined. • Highest removal of PAHs was detected by using cinnamon and vanilla and reaching to 80%. • Assessment of antioxidant activity of food additives was performed; vanilla and cinnamon were similar in antioxidantactivity. • Screening of bioactive components found in cinnamon, vanilla and mastic showed presence of essential oils, phenolic compounds and terpenoids. |