الفهرس 
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Abstract
The objectives of this study were to explore the extraction method of natural pigments from some plants grown in Egypt, i.e. the Egyptian cultivars of pumpkin and alfalfa. The chemical composition of the flesh, pulp and peels of pumpkin cultivar as well as leaves and stem of alfalfa cultivar were determined. The optimal conditions for extracting carotenoids and chlorophyll pigments from the dry botanical parts of pumpkin and alfalfa were investigated, which included the determination of the type of solvent system used and duration of extraction time. Solvent used in the extraction of carotenoids were petroleum ether, ethanol and hexane, where the best solvent for extraction was petroleum ether. The highest extracted carotenoids concentration was from pulp, followed by flesh and then peels (29.76, 27.878 and 23.286 μg/g, respectively). Solvents used to extract chlorophyll from leaves and stem of alfalfa were methanol absolute, ethanol 77%, ethanol, acetone, hexane and toluene. Concentrations of chlorophyll pigment extracted from leaves and stem with the best extracting solvents methanol absolute and ethanol 77%. were 62.302, 23.744 mg/L, 60.063, 13.011 mg/L respectively. The concentration of carotenoids extracted from peels and flesh pumpkin was estimated using the calculation from HPLC chromatograms, where they reached 4.747 and 9.874 mg/100 g, respectively. Moreover, characterization of the extracted pigments through the study of effects of temperature and pH values and the pigment stability at variable temperatures and pH conditions were fully investigated. Some food products, i.e., noodles and jelly were prepared with different levels from the experimental extracted pigments to test their suitability to impart color to the product according to results of their sensory evaluation tests, their microbiological examination and also the analysis of their chemical composition. The study will help improve extraction of pigments from alfalfa and pumpkin and promote better utilization of the extracted carotenoids and chlorophyll pigments to be used as natural colorants in food products and during their processing.
Keywords Pumpkin, Alfalfa, Natural pigments, Carotenoids, Chlorophyll, Chemical composition, HPLC, Effect of Thermal stability, Application in foods.