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The aim of this work is to investigate the structural features, physicochemical, rheological, and emulsifying properties of pectin extracted from pumpkin “Cucurbita maxima” pulp and peel. After the peel and pulp of fresh pumpkin were solubilized in water at high temperature (80°C) and clarification, the obtained filtrate was treated with aluminum sulphate, which precipitates a fibrous coagulum. The results found that the major functional groups of pectin isolates identified by Fourier transform infrared are: –OH, CH2, C═C, –C–O–C–, and CH3. The results obtained using nuclear magnetic resonance methods suggest that these polysaccharides consist of two domains: the first one is homogalacturonan and the second is formed by rhamnogalacturonan. Mineral and metal ions on pectin surface detected using scanning electron microscopy coupled to energy dispersive X-ray analysis were different pulp and peel pectin. Rheological behavior of these biopolymers is suitably represented by the Herschel–Bulkley and power law models. The extracted pectin has a viscosity spectrum expressed by the following properties: G′, G′′, G*, and ∣ η ̇ ∣ ( ω ) | \dot{\eta }| (\omega ) which, respectively, have the following values: 0.28–57.63, 0.15–34.38, 0.39–67.12, and 1.82–831.08 Pa s. These macromolecules have a negative charge on their surface. Rheological properties and emulsifying activity are significantly influenced by the structural composition and physicochemical properties.

The objective of this study was to optimize the extraction conditions for phenolic compounds, total flavonoids, and antioxidant activity from Deglet-Nour variety. The extraction of active components from natural sources depends on different factors. The knowledge of the effects of different extraction parameters is useful for the optimization of the process, as well for the ability to predict the extraction yield. The effects of extraction variables, namely types of solvent (methanol, ethanol and acetone) and extraction time (1h, 6h, 12h and 24h) on phenolics extraction yield were evaluated. It has been shown that the time of extraction and types of solvent have a statistically significant influence on the extraction of phenolic compounds from Deglet-Nour variety. The optimised conditions yielded values of 80.19 ± 6.37 mg GAE/100 g FW for TPC, 2.34 ± 0.27 mg QE/100 g FW for TFC and 90.20 ± 1.29% for antioxidant activity were methanol solvent and 6 hours of time. According to the results obtained in this study, Deglet-Nour variety can be considered as a natural source of phenolic compounds with good antioxidant capacity., {"references":["","A. S. Truswell, \"ABC of nutrition (4th ed.)\". London: BMJ Books, 2003.","R. E. C. Wildman, \"The nutritionist: food, nutrition and optimal health (2nd ed.)\". New York: Taylor & Francis, 2009.","W. Vermerris, & R. Nicholson, \"Phenolic compound biochemistry\". Springer: Netherlands, 2006.","A. Bucić-Kojić, M. Planinić, S. Tomas, S. Jokić, I. Mujić, M. Bilić, & D. Velić, \"Effect of Extraction Conditions on the Extractability of Phenolic Compounds from Lyophilised Fig Fruits (Ficus carica L.)\". Pol. J. Food Nutr. Sci., 61 (3), 195-199, 2011.","R. Marija, Z. Zoran, J. Stela, & V. Senka, \"Determination of optimal extraction parameters of mulberry leaves using Response Surface Methodology (RSM)\". Romanian Biotechnological Letters, 17 (3), 7295-7308, 2012.","AOAC International, \"Official methods of analysis (16th Ed.)\". Gaithersburg, MD, method 920.151, 1998.","A. Rajaei1, M. Barzegar1, Z. Hamidi1, & M. A. Sahari, \"Optimization of Extraction Conditions of Phenolic Compounds from Pistachio (Pistachia vera) Green Hull through Response Surface Method\". J. Agr. Sci. Tech., 12, 605-615, 2010.","Y. Cai, Q. Luo, M. Sun, & H. Corke, \"Antioxidant activity and phenolic compounds of 112 traditional Chinese medicinal plants associated with anticancer\". Life Sciences, 74, 2157-2184, 2004.","N. Gursoy, C. Sarikurkcu, M. Cengiz, & M. H. Solak, \"Antioxidant activities, metal contents, total phenolics and flavonoids of seven Morchella species\". Food and Chemical Toxicology, 47 (9), 2381-2388, 2009.\n[10] A. Mansouri, G. Embarek, E. Kokkalou, & P. Kefalas, \"Phenolic profile and antioxidant activity of the Algerian ripe date palm fruit (Phoenix dactylifera)\". Food chemistry, 89, 411-420, 2005.\n[11] C. Sanchez-Moreno, \"Methods used to evaluate the free radical scavenging activity in foods and biological systems\". Food Science and Technology International, 8 (3), 121-137, 2002.\n[12] M. Lu, B. Yuan, M. Zeng, & J. Chen, \"Antioxidant capacity and major phenolic compounds of spices commonly consumed in China\". Food Research International, 44 (2), 530-536, 2011.\n[13] F. Biglari, A.F.M. Alkarkhi, & A.M. Easa, \"Antioxidant activity and phenolic content of various dates palm (Phoenix dactylifera) fruits from Iran\". Food Chemistry, 107, 1636-1641, 2008.\n[14] P. K. Vayalil, “Date fruits (Phoenix dactylifera Linn): An emerging medicinal food”. Critical Reviews in Food Science and Nutrition, 52 (3), 249-271, 2012.\n\n "]}